Wiseman: Armyworm Symposium - ‘94 397 DEDICATION OF 1994...

Wiseman: Armyworm Symposium - ‘94

397

DEDICATION OF 1994 ARMYWORM SYMPOSIUM TODR. ROBERT L. BURTON AND MR. E. A. HARRELL:

EXPERTS IN INSECT REARING

B. R. W

ISEMAN

Insect Biology & Population Management Research LaboratoryTifton, GA 31793-0748

A

BSTRACT

The 1994 Symposium on Armyworms (previously Fall Armyworm Symposium) atthe Southeastern Branch of the Entomological Society of America is dedicated to “Dr.Robert L. Burton and Mr. E. A. Harrell: Experts in Insect Rearing.” Dr. Burton, an en-tomologist (1964-1970), and Mr. E. A. Harrell, an agricultural engineer (1961-1980),were employed by the U. S. Department of Agriculture, Agricultural Research Serviceat the Southern Grains Insects Research Laboratory at Tifton, GA. The systems theydeveloped provided the means by which the fall armyworm,

Spodoptera frugiperda

(J.E. Smith), could be reared in mass numbers on a meridic diet that resulted in qualityeggs, larvae, pupae, and adult insects.

Key Words: Fall armyworm, rearing, mechanization, diet.

R

ESUMEN

El Simposio de 1994 sobre los Gusanos Trozadores (previamente Simposio sobrelos Gusanos Trozadores de Otoño) en la Rama Sureste de la Sociedad Entomológica deAmérica estuvo dedicado al tema “Dr. Robert L. Burton y Sr. E. A. Harrel: Expertos enCría de Insectos”. El Dr. Burton, entomólogo (1964-1970), y el Sr. E. A. Harrel, inge-niero agrónomo (1961-1980), fueron empleados del Servicio de Investigación Agrícoladel Departamento de Agricultura de los Estados Unidos, en el Laboratorio Sur de In-vestigación de Insectos de los Granos en Tifton, Georgia. Los sistemas que ellos desa-rrollaron posibilitaron la cría masiva del gusano trozador,


(J.E. Smith), en una dieta merídica que tuvo como resultado la producción de huevos,

larvas, pupas e insectos adultos de calidad.

The 1994 “Symposium on Armyworms” (previously “Fall Armyworm Symposium”)presented at the Southeastern Branch Meeting of the Entomological Society of Amer-ica is hereby dedicated to “Dr. Robert L. Burton and Mr. E. A. Harrell: Experts in In-sect Rearing.”

B

IOGRAPHIES

Dr. Robert L. Burton (Fig. 1) of Stillwater, OK, was born on August 23, 1936 in Ant-lers, OK, to Charles and Sally (Holton) Burton. He married Sylvia J. Gentry Septem-ber 1, 1960 in Durant, OK. They have two sons, Robert L. Burton Jr. of Dana Point,CA, and Brian Gentry Burton of Stillwater. Dr. Burton died February 3, 1993 in theSt. Francis Medical Center in Tulsa at the age of 56.

Dr. Burton became interested in Entomology early in his education. He attendedEastern Oklahoma College, Southeastern State College, the University of Oklahoma,

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, Vol. 77, No. 4 (1994).

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398

Florida Entomologist

77(4) December, 1994

and Oklahoma State University. Dr. Burton received his B. S. and M. S. degrees in en-tomology from Oklahoma State University in 1963 and 1964, respectively. He wasfirst employed as an entomologist in 1961 with Standford-Vaddar Entomology Serviceof Plainview, TX, and then as a Research Assistant with Oklahoma State in 1963. Dr.Burton joined the U. S. Department of Agriculture, Agricultural Research Service in1964 with his first assignment at the Southern Grain Insects Research Laboratory inTifton, GA. He quickly assumed a leadership role as the entomologist in charge of in-sect rearing. In 1970, Dr. Burton was transferred to Stillwater where he continuedboth his work and studies. He completed his Ph. D. degree in 1974. Dr. Burton contin-ued his work at Stillwater until his death, at which time he had attained the positionof Supervisory Entomologist, Research Leader and Director of the USDA-ARS PlantScience and Water Conservation Laboratory as well as adjunct Professor of Entomol-ogy at Oklahoma State University.

Dr. Burton authored and co-authored 126 scientific publications during his 28years of dedicated service to agriculture. He also presented more than 114 scientificpresentations during his tenure with ARS. Dr. Burton was recognized as a world au-thority in the areas of insect diets and the laboratory production of insects.

Mr. Edsel A. Harrell (Fig.2) began his life on a little farm in South Georgia aboutfour miles north of Whigham. He was born on October 17, 1924, the son of C. Braxtonand Mabel (Moore) Harrell. Edsel believed that there was a better life somewhere

Fig. 1. Dr. Robert L. Burton, USDA, ARS Supervisory Entomologist (1936-1993).


399

other than shaking peanuts and picking cotton by hand. Upon graduation from highschool in Whigham, he left the farm for Alexandria, VA, where he began an appren-ticeship as a machinist in a torpedo plant. During World War II, Edsel served hiscountry honorably in the Army Signal Corps on isolated islands in the Pacific. His spe-cific assignment was cryptography. He was discharged in January of 1946.

Edsel then enrolled in Abraham Baldwin Agricultural College in Tifton, GA, topursue a degree in Agricultural Engineering. He obtained his BSAE in 1950 and hisMSAE in 1951 from the University of Georgia. (An interesting note: Edsel taughteighth and ninth grade math and coached the boys and girls basketball teams atWhigham high school while he was obtaining his BS degree). During this time he metand married Martha E. Elkins. They have three children: Edsel Jr. of Dallas, TX, Deb-bie of Nashville, TN, and Karen of Watkinsville, GA, and five grandchildren.

Mr. Harrell began his research career as an Agricultural Engineer with the U. S.Department of Agriculture at the U. S. Cotton Ginning Laboratory at Stoneville, MS,in 1951. He transferred in 1961 to the Southern Grain Insects Research Laboratory(SGIRL) in Tifton, GA, where he was in charge of the Pest Control Research Projectuntil his retirement in 1980. It was during this period of time that Edsel and Dr. Bur-ton teamed up to solve some of the most difficult problems encountered in the massrearing of

Helicoverpa zea

(Boddie) and


(J. E. Smith).Mr. Harrell authored or co-authored more than 60 scientific publications during

his 30 years of productive service and he presented more than 40 scientific presenta-

Fig. 2. Mr. Edsel A. Harrell, USDA, ARS Agricultural Engineer (1924--).

400



tions during his tenure with ARS. Mr. Harrell is the senior scientist on six separatepatents. Mr. Harrell is recognized as an expert in the mechanization of insect rearingand insect control.

R

ESEARCH

A

CHIEVEMENTS

The fall armyworm has been reared in the laboratory with a variety of techniques.The first cultures were maintained on foliage of corn, millet, bean and bean pods. Be-cause of the demands for larger numbers of insects it was inevitable that meridic dietsand mass-production rearing equipment be developed. Dr. Burton (Burton 1967) de-veloped an artificial diet for fall armyworm and was probably among the first to rearit continuously on a meridic diet. Dr. Burton also developed a detailed description ofthe rearing procedures that included diet preparations, egg incubation, diet dispens-ing and manipulation of the larvae as well as some of the first estimates of mass rear-ing costs. About this same time Burton and Harrell began to develop original devices(Burton et al. 1966) for speeding up the procedures of mass rearing. The first two de-vices developed were the diet-dispensing and larvae-isolating systems. Then came thedevelopment of an automated packaging system (Burton & Cox 1966). The machinedispensed 1-oz plastic cups, each filled with a selected amount of artificial diet, dis-pensed larvae onto the diet and then, in one continuous process, capped the cup. Bur-ton & Harrell (1966) then modified the larval dispensing machine to provide morestability, thus providing a much smoother operation. In 1968, Mr. Harrell and co-workers (Harrell et al. 1968) developed equipment and a mechanized system of col-lecting pupae of the fall armyworm from rearing containers. This entire system ofrearing the fall armyworm, and various modifications thereof (Burton & Perkins1989), has been used at the Southern Grain Insects Research Laboratory, which isnow the Insect Biology and Population Management Research (IBPMRL) since about1966.

Mr. Harrell was instrumental in the erection of a 40 x 100 ft building which nowhouses the rearing section of at IBPMRL. The building was originally built for thepurpose of housing a mass rearing system for the boll weevil (Harrell & Griffin 1981).A side note to this is that Mr. Harrell developed equipment for use on a form-fill-sealmachine that was used in the mass production of insects. Harrell et al. (1973) devel-oped an insect diet filler to be used on the form-fill-seal machine which could fill 32cavities with diet in less than 2 sec. Mr. Harrell and co-workers (1974a) also builtequipment that could mix and sterilize economically large amounts (up to 68 gallonsper hour) of insect diet. Then, Mr. Harrell developed equipment for use on the form-fill-seal machine (Harrell et al. 1974b) to infest cavities (cells) with insect eggs at ratesup to 544 cavities per minute. Mr. Harrell later built two environmental rooms withinthe building to study environmental effects on growth of insects (Harrell et al. 1979).The rooms had separate air-distribution systems designed to maintain a uniform andconstant temperature within

±

1.1 C.

H

ONORARIUM

The scientists that have spent time in research at the IBPMRL, and others thathave used the fall armyworm reared there, are deeply indebted to Dr. Robert L. Bur-ton and Mr. E. A. Harrell for their tireless efforts in the development of a completerearing system that has provided adequate numbers of quality fall armyworm eggs,larvae, pupae and adults.


401

Therefore, it is with high regard and great pleasure that we dedicate this Army-worm Symposium to Dr. Robert L. Burton and Mr. E. A. Harrell in honor of their con-tributions to insect rearing.

L

ITERATURE

CITED

B

URTON

, R. L. 1967. Mass rearing the fall armyworm in the laboratory. U. S. Depart-ment of Agriculture. Agricultural Research Service. ARS 33-117. 12 pp.

B

URTON

, R. L.,

AND

H. C. C

OX

. 1966. An automated packaging machine for lepidopter-ous larvae. J. Econ. Entomol. 59: 907-909.

B

URTON

, R. L.,

AND

E. A. H

ARRELL

. 1966. Modification of a lepidopterous larva dis-penser for a packaging machine. J. Econ. Entomol. 59: 1544-1545.

B

URTON

, R. L., E. A. H

ARRELL

, H. C. C

OX

,

AND

W. W. H

ARE

. 1966. Devices to facilitaterearing of lepidopterous larvae. J. Econ. Entomol. 59: 594-596.

B

URTON

, R. L.,

AND

W. D. P

ERKINS

. 1972. WSB, a new laboratory diet for the corn ear-worm and the fall armyworm. J. Econ. Entomol. 65: 385-386.

B

URTON

, R. L.,

AND

W. D. P

ERKINS

. 1989. Rearing the corn earworm and the fall ar-myworm for maize resistance studies, pp. 37-45

in

Toward insect resistantmaize for the third world: Proc. International Symposium on Methodologies forDeveloping Host Plant Resistance to Maize Insects. CIMMYT.

H

ARRELL

, E. A.,

AND

J. G. G

RIFFIN

. 1981. Facility for mass rearing of boll weevils: En-gineering aspects. U. S. Department of Agriculture. Science and Education Ad-ministration. Advances in Agricultural Technology. AAT-S-19. 77 pp.

H

ARRELL

, E. A., W. W. H

ARE

,

AND

R. L. B

URTON

. 1968. Collecting pupae of the fall ar-myworm from rearing containers. J. Econ. Entomol. 61: 873-876.

H

ARRELL

, E. A., W. D. P

ERKINS

,

AND

B. G. M

ULLINIX

, JR. 1979. Environmental roomsfor insect rearing. Trans, ASAE. 1979: 922-925.

H

ARRELL

, E. A., A. N. S

PARKS

, W. W. H

ARE

,

AND

W. D. P

ERKINS

. 1974a. Processing di-ets for mass rearing of insects. U. S. Department of Agriculture. AgriculturalResearch Service. ARS-S-44. 4 pp.

H

ARRELL

, E. A., A. N. S

PARKS

, W. D. P

ERKINS

,

AND

W. W. H

ARE

. 1973. An insect dietfiller for an in line form-fill-seal machine. J. Econ. Entomol. 66:1340-1341.

H

ARRELL

, E. A., A. N. S

PARKS

, W. D. P

ERKINS

,

AND

W. W. H

ARE

. 1974b. Equipment toplace insect eggs in cells on a form-fill-seal machine. U. S. Department of Agri-culture. Agricultural Research Service. ARS-S-42. 4 pp.

402



REPRODUCTIVE POTENTIAL OF ONCE-MATED MOTHS OF THE FALL ARMYWORM (LEPIDOPTERA: NOCTUIDAE)

C. E. R

OGERS

AND

O. G. M

ARTI

, J

R

. Insect Biology and Population Management Research LaboratoryAgricultural Research Service, U. S. Department of Agriculture

Tifton, GA 31793-0748

A

BSTRACT

A laboratory study of the effects of age at a single mating on the reproductive po-tential of the fall armyworm,


(J. E. Smith), revealed that of389 pairs of moths tested, 106, 281, and 2 pairs transferred 0, 1, or 2 spermatophores,respectively. Pairs that did not transfer a spermatophore mated when males and fe-males averaged 7.0 and 8.8 days of age, respectively. Pairs transferring a single sper-matophore mated when males and females averaged 5.9 and 6.3 days of age,respectively. The pairs transferring two spermatophores during one-night’s pairingaveraged 8 and 9 days of age at mating for males and females, respectively. The ageof females at a single mating significantly affected their fecundity (r = -0.92;

P

<0.01),fertility (r = -0.61;

P

<0.01), and longevity (r = 0.83;

P

<0.01). Male age at a single mat-ing significantly influenced only the fertility of eggs laid by their respective femalepartner (r = -0.92;

P

<0.01). Two days post-emergence was the optimum age for matingby both male and female moths for maximum fecundity and fertility. Delaying matingby females significantly lengthened their survival.

Key Words:


, fecundity, fertility, longevity

R

ESUMEN

Un estudio de laboratorio acerca de los efectos de la edad en el momento del primerapareo sobre el potencial reproductivo del gusano trozador,


(J.E. Smith), reveló que de 389 parejas de polillas, 106, 281, y 2 parejas transfirieron 0,1, y 2 espermatóforos, respectivamente. Las parejas que no transfirieron ningún es-permatóforo se aparearon cuando los machos y hembras tenían una edad promedio de7.0 y 8.8 días, respectivamente. Las parejas que transfirieron un solo espermatóforose aparearon cuando los machos y las hembras tenían un promedio de 5.9 y 6.3 díasedad, respectivamente. Las parejas que transfirieron dos espermatóforos durante unapareamiento de una noche tuvieron un promedio de 8 y 9 días de edad en los machosy hembras, respectivamente. La edad de las hembras en el momento del aparea-miento afectó significativamente su fecundidad (r = -0.61; P <0.01), fertilidad (r =0.83; P <0.01), y longevidad (r = 0.83; P< 0.01). La edad del macho en el momento delapareamiento influyó solamente en la fertilidad de los huevos puestos por su respec-tiva pareja (r = 0.60; P = 0.01). La edad óptima para el apareo fué de dos días despuésde la emergencia, tanto para el macho como para la hembra, y a esta edad se obtuvie-ron fecundidad y fertilidad máximas. El retardo en el apareo de las hembras alargó

significativamnete su sobrevivencia.

The reproductive potential, behavior, fecundity, and fertility of the fall armyworm,


(J. E. Smith), have been studied under a variety of natural andcontrolled environmental conditions (Luginbill 1928, Barfield & Ashley 1987, Sim-



, Vol. 77, No. 4 (1994).

FEO




Rogers and Marti: Armyworm Symposium - ‘94

403

mons & Lynch 1990, Simmons & Marti 1992, Simmons & Rogers 1994). Due to its pe-rennial pest status in the southeastern United States, numerous strategies formanaging the fall armyworm have been proposed, including the combination of two ormore into regional management schemes (Knipling 1980). To accurately evaluate theefficacy of these strategies, it often is necessary to standardize one or more biologicalparameters of the fall armyworm in a controlled environment. We recently reportedthat the age of female moths at their first mating significantly affected their fecundity,fertility, and longevity (Rogers & Marti 1994). Here we report the effects of moth ageat a single mating on the reproductive potential of the fall armyworm.

M

ATERIALS

AND

M

ETHODS

Experimental insects were from an established laboratory colony of the fall army-worm that had been collected from corn and maintained on a pinto bean-based diet(Burton 1967, Perkins 1979). As moths emerged, they were placed individually in a0.6-liter cardboard container, provided a 10% honey solution for nourishment, andmaintained at 27

°

C and 70-75% RH in a 14:10 (L:D) cycle. To determine the effect ofage at a single mating on fecundity and fertility of the fall armyworm, pairs of differ-ent male/female age combinations were established. The age of males and females atpairing ranged from 1-11 days and 1-14 days post-emergence, respectively. Tests en-compassed 18 independent trials, each of which contained from 15 to 24 mating pairs.Mating pairs were maintained overnight in the conditions mentioned above in 0.6-li-ter cardboard cages with their tops and bottoms covered with mesh netting. Cageswere lined with waxed paper to facilitate removal and counting of eggs. Males werediscarded the morning after pairing. Females were maintained in their respectivecages until they died. Cages were examined daily to record data on moth mortality/longevity and the number of eggs laid. Dead females were dissected to determine thenumber of spermatophores they received from males while copulating. The number ofunhatched eggs and viable larvae was used to compute daily fecundity and fertility foreach mating pair.

All data were subjected to an analysis of variance by the General Linear ModelProcedure, and significantly different means were separated by the least significantdifference (LSD) test (SAS Institute 1989).

R

ESULTS

AND

D

ISCUSSION

Significant differences (F = 4.97; df = 17, 386;

P

<0.01) occurred across trials for allparameters studied, indicating that the age of males and females at mating inter-acted to affect the reproductive potential of the fall armyworm (Fig. 1). Pairs com-posed of both young males and young females produced eggs having the highestfertility. When either sex was aged, fertility of the eggs was reduced. However, the ageof females at mating had a greater influence on egg fertility than the age of males.

Of the 389 pairs, 106 females received no spermatophores, 281 females receivedone spermatophore and two females received two spermatophores during a singlenight of pairing. Spermatophore transfer during moth mating may have been affectedby female age (r = 0.71;

P

<0.01) but not by male age (r = 0.30;

P

<0.01) nor by the com-bination of male-female ages (Pearson correlation coefficient). Pairings resulting inthe transfer of a single spermatophore involved males and females averaging 5.9 and6.3 days of age, respectively. For pairs where no spermatophore was transferred, maleand female age at mating averaged 7.0 and 8.8 days, respectively. Survival of femalesaveraged 16.3 to 16.9 days, regardless of whether 0, 1, or 2 spermatophores were re-

404



ceived. The fertility (

P

<0.05) of eggs from a single mating averaged 0, 20.4, and 45.5%for females receiving 0, 1, or 2 spermatophores, respectively. Total fecundity averaged226.5, 1,134.7, and 1,026.5 eggs for females receiving 0, 1, or 2 spermatophores, re-spectively. Since this study concerns the reproductive potential for females restrictedto a single opportunity for mating, analyses are reported for females which receivedonly a single spermatophore.

The age of females at a single mating significantly affected the number of eggsthey laid (F = 8.21; d.f. = 10, 280;

P

<0.01), fertility of the eggs (F = 9.14; d.f. = 10, 280;

P

<0.01), and longevity of mated females (F = 10.24; d.f. = 10, 281;

P

<0.01) (Table 1).Females which mated at the age of 1-5 days laid more eggs than females which matedat an older age. Also, females which mated at 11-14 days of age laid the fewest eggs(about 50% as many as females that mated from 1 to 5 days post-emergence) (Fig. 2).

The mean fertility of eggs laid by females mated at 2 days of age was significantlygreater than it was for eggs laid by younger or older females (Table 1). The lowest fer-tility occurred in eggs laid by females whose mating was delayed until 7 days and 10-13 days post-emergence. Seven-day-old females mated with 9- and 11-day-old males.

Figure 1. Interaction of male and female age at mating on egg fertility in once-mated fall armyworm moths. Data points represent means within trials.

Rogers and Marti: Armyworm Symposium - ‘94

405

Ten-day-old females mated with 1- and 10-day-old males. Eleven-day-old femalesmated with 8-day-old males, while 13-day-old females mated with 4- and 10-day-oldmales. Surprisingly, females that mated one day post-emergence laid eggs that were

T

ABLE

1. E

FFECTS

OF

FEMALE

AGE

AT

MATING

ON

FECUNDITY

,

FERTILITY

,

AND

LONGEV-ITY

OF

FALL

ARMYWORM

(

ONCE

-

MATED

MOTHS

).

Female Age

(Days) N

a/

Total No. Eggs Laid (x

±

S.E.)

b,c/

% Eggs Hatching (x

±

S.E.)

b,d/

No. Days

/

Lived(x

±

S.E.)

b,e/

1 49 1,387

±

79a 28

±

4b 15

±

1c2 23 1,569

±

115a 67

±

6a 12

±

1d3 12 1,402

±

159a 29

±

8b 14

±

1cd4 37 1,269

±

91ab 14

±

5bc 15

±

1c5 20 1,294

±

123a 23

±

7b 15

±

1c7 39 1,150

±

88b 9

±

5c 17

±

1b8 21 1,002

±

120bc 25

±

6b 15

±

1c10 24 847

±

113cd 6

±

6c 21

±

1a11 14 603

±

147d 5

±

8c 17

±

1bc13 32 639

±

98d 5

±

5c 20

±

1a14 10 768

±

174d 15

±

9bc 19

±

1ab

a/

Number of females per respective age across trials.

b/

Means within a column followed by different letters are significantly different (

P

< 0.05) by the SAS LSDtest.

c/

Least significant difference = 341; r = -0.92 (

P

<0.01)

d/

Least significant difference = 18; r = -0.61 (

P

<0.01)e/ Least significant difference = 3; r = 0.83 (P <0.0l)

Figure 2. Correlation between egg production and age at mating by once-mated fe-males of the fall armyworm. Data points represent means within trials.

406 Florida Entomologist 77(4) December, 1994

less fertile than eggs laid by females mated 2 days post-emergence. However, 1-day-old females mated with 1-, 5-, and 11-day-old males, while 2-day-old females matedonly with 2-day-old males.

Fertility of eggs from a single mating remained relatively high (>80-97%) for about7 days for pairs composed of 2-day-old males and females (Fig. 3). Fertility of eggsfrom pairs mated at 1 day of age declined to about 35% by day 3 post-mating. Fertilityfrom 3-day-old pairs was below 50% and declined to about 20% by day 7 post-mating.Mating between 1-day-old females and 10-day-old males resulted in eggs with 96.99%fertility that remained >90% fertile from 2 through 8 days. The preceding data indi-cate that female age at mating is more important in determining fertility than maleage. This is further indicated by a significant negative correlation between mean per-cent fertility and age of females at mating (Fig. 4), while the effects of male age on per-cent fertility is relatively benign (r = -0.32; P >0.10). The sum of male and female ageat mating also significantly affected fertility of eggs on the second day post-mating(Fig. 5). As the sum of ages of mating males and females advanced beyond 4 days, thefertility of eggs declined as the combined ages of the pairs increased.

Both the fecundity and fertility of fall armyworm females receiving a single sper-matophore were less in this study than has been reported elsewhere (Vickery 1929,Simmons & Lynch 1990, Rogers & Marti 1994); however, our females were restrictedto a single mating at a specific age. In considering only females which laid fertile eggs,both fecundity (x = 1,702.22 ± 111.7 no. eggs per /) and fertility (x = 73.6 ± 6.8% eggshatching) were higher for females mated at 2 days of age than they were for all fe-males mated at the same age. Simmons & Marti (1992) reported that fall armywormfemales mate an average of 3.7 times, and that two matings in a single night are com-mon. Simmons & Rogers (1994) reported that females of the fall armyworm mate inas few as 11.5 hours after emergence, but that such matings result in eggs with a lowfertility.

Figure 3. Sustained fertility of eggs from pairs composed of once-mated, two-day-old fall armyworm males and females. Data points represent means within trials.

Rogers and Marti: Armyworm Symposium - ‘94 407

Fertility of eggs laid by females which had mated with 2-day-old males was signif-icantly (F = 8.75; d.f. = 10, 280; P <0.01) greater than the fertility of eggs laid by fe-males which had mated with either younger or older males (Table 2). Fertility of eggslaid by females which had mated with males 8 days of age or older was extremely low

Figure 4. Effects of age of moths at mating on egg fertility two days post-mating inonce-mated fall armyworm moths. Data points represent means within trials.

Figure 5. Effects of summed age of mating pairs on fertility in once-mated fall ar-myworm moths. Data points represent means within trials.


(<9%). The age of females mating with 8- to 11-day-old males ranged from 1-13 dayspost-emergence. Although the effects of male age at mating on fall armyworm repro-ductive potential beyond the second day post-emergence were difficult to assess, theinteraction of male and female ages appeared to contribute to egg fertility (Fig. 5). Forexample, combined age of 4 days for males and females at mating resulted in signifi-cantly higher fecundity (F = 5.6; d.f. = 10, 280; P <0.01) in mated females and signif-icantly higher (>2x) egg fertility (F = 7.44; d.f. = 10, 280; P <0.01). Age combinationsgreater than 16-17 days resulted in pairs producing fewer eggs with a lower fertilitythan pairs of younger males and females.

The longevity of fall armyworm females was significantly affected by the age atwhich they mated (Table 1). Females that were denied mating until 10, 13, and 14days of age lived significantly longer (x = 20.6 ± 1.8 days) than females which matedduring the first 8 days post-emergence (x = 14.7 ± 1.1 days). The association of femalelongevity with age at mating is expressed as a highly significant correlation. This re-lationship gives credence to an oogenesis-flight syndrome in the fall armyworm thatcommonly is found in other migratory species of insects (Rankin & Burchsted 1992),in which early flight and reproduction are physiologically antagonistic. Such a phys-iologically antagonistic relationship has enabled the evolution of migration in the lifehistory of some species, e.g., S. exempta (Walker) (Gatehouse 1986).

Although the effects of male age at mating on the reproductive potential of the fallarmyworm were less dramatic than the effects of female age, the age of males at mat-ing nevertheless affected both fecundity of mated females, and the fertility of theireggs (Table 2). Females of varying age that were mated with 2- to 3-day-old males laidsignificantly (F = 3.17: d.f. = 10, 280; P <0.01) more eggs than females mating witholder males. Male age at mating beyond three days post-emergence was less impor-tant as a contributor toward mated female fecundity. How young males may have con-tributed to the fecundity of their mates is unclear. However, Rankin & Burchsted

TABLE 2. EFFECTS OF MALE AGE AT MATING ON FECUNDITY AND FERTILITY IN THE FALLARMYWORM (ONCE-MATED MOTHS).

Male Age (Days) Na/

Total No. Eggs Laid(x ± S.E.)b,c/

% Eggs Hatching(x ± S.E.)b,d/

1 40 1,251 ± 94ab 24 ± 5b2 23 1,569 ± 124a 67 ± 6a3 12 1,402 ± 172a 29 ± 8b4 36 982 ± 99bc 17 ± 5bc5 17 1,183 ± 145b 25 ± 7b6 21 1,002 ± 130b 25 ± 6b7 28 1,131 ± 113b 22 ± 6b 8 14 603 ± 159c 5 ± 8c9 15 1,099 ± 154b 0 ± 8c

10 66 1,066 ± 73b 9 ± 4c11 9 1,117 ± 199b 0 ± 10c

a/Number of males per respective age across trials.b/Means within a column followed by different letters are significantly different (P <0.05) by the SAS LSD test.c/Least significant difference = 383; r = -0.30 (P >0.10)d/Least significant difference = 19; r = -0.92 (P <0.01)

Rogers and Marti: Armyworm Symposium - ‘94 409

(1992) reported that males of a migratory grasshopper, Melanoplus sanguinipes (Fab-ricius), appear to transfer key proteins to females while mating that promote oogen-esis and oviposition. Snow & Carlysle (1967) reported that unmated males of the fallarmyworm incorporate a brownish-black pigment in the ductus ejaculatorius simplexthat is transferred to females with a spermatophore on their first mating. Perhaps thebrownish-black pigmented material transferred with a male’s spermatophore contrib-utes to the reproductive potential of mated females. If this pigmented material trans-ferred from young males contributes to female fecundity, our data indicates that itsimportance diminishes in males which mate after day three post-emergence.

Many factors (e.g., plant resistance, irradiation, chemosterilants, biologicalagents, number of matings, colony age, host strain, diet, pheromones, toxic chemicals,cultural strategies, etc.) are known to adversely affect the reproductive potential ofthe fall armyworm (Young et al. 1968, Lynch et al. 1980, Hamm & Hare 1982, Car-penter et al. 1986, Gross & Pair 1986, Silvain 1986, Simmons & Lynch 1990, Sen-Seong et al. 1985, Chandler & Sumner 1991, Quisenberry 1991, Pashley et al. 1992,and Rogers & Marti 1994). Knowledge of the individual and collective effects of thesefactors on the reproductive potential of the fall armyworm is critical for the imple-mentation of an effective regional management strategy (Knipling 1980). Of equal im-portance is a knowledge of the effects of age at mating on the reproductive potentialof the fall armyworm if efficacious propagation, treatment, and augmentation of in-sects are to be realized to support regional suppression of fall armyworm populations.

The age of fall armyworm moths at mating when only a single opportunity for mat-ing exists is critical for the sustainability of reproducing populations. Female age ata single mating is more important than male age for maintenance of a high reproduc-tive potential. However, two days post-emergence for both males and females is theoptimum age for mating for enhanced reproductive potential in the fall armyworm.

REFERENCES CITED

BARFIELD, C. S., AND T. R. ASHLEY. 1987. Effects of corn phenology and temperatureon the life cycle of the fall armyworm Spodoptera frugiperda (Lepidoptera: Noc-tuidae). Florida Entomol. 70: 110-116.

BURTON, R. L. 1967. Mass rearing the fall armyworm in the laboratory. USDA, ARS-33-177, Gov. Print. Office, Wash., DC.

CARPENTER, J. E., J. R. YOUNG, AND A. N. SPARKS. 1986. Fall armyworm (Lepidoptera:Noctuidae): Comparison of inherited deleterious effects in progeny from irradi-ated males and females. J. Econ. Entomol. 79: 46-49.

CHANDLER, L. D., AND H. R. SUMNER. 1991. Effect of various chemigation methodolo-gies on suppression of the fall armyworm (Lepidoptera: Noctuidae) in corn.Florida Entomol. 74: 270-279.

GATEHOUSE, A. G. 1986. Migration in the African armyworm, Spodoptera exempta, pp.128-144 in Danthanarayana, W. [ed.]. Insect flight: dispersal and migration.Berlin/Heidelberg: Springer-Verlag, 289 pp.

GROSS, H. R., AND S. D. PAIR. 1986. The fall armyworm: status and expectations of bi-ological control with parasitoids and predators. Florida Entomol. 69: 502-515.

HAMM, J. J., AND W. W. HARE. 1982. Application of entomopathogens in irrigation wa-ter for control of fall armyworms and corn earworms (Lepidoptera: Noctuidae)on corn. J. Econ. Entomol. 75: 1074-1079.

KNIPLING, E. F. 1980. Regional management of the fall armyworm - a realistic ap-proach. Florida Entomol. 63: 468-480.

LUGINBILL, P. 1928. The fall armyworm. U. S. Dept. Agric. Tech. Bull. 34. Gov. Print.Office, Wash., DC.


LYNCH, R. E., P. B. MARTIN, AND J. W. GARDNER. 1980. Cultural manipulation ofcoastal bermudagrass to avoid losses from the fall armyworm. Florida Ento-mol. 63: 411-419.

PASHLEY, D. P., A. M. HAMMOND, AND T. N. HARDY. 1992. Reproductive isolating mech-anisms in fall armyworm host strains (Lepidoptera: Noctuidae). Ann. Entomol.Soc. America 85: 400-405.

PERKINS, W. D. 1979. Laboratory rearing of the fall armyworm. Florida Entomol. 62:87-91.

QUISENBERRY, S. S. 1991. Fall armyworm (Lepidoptera: Noctuidae) host strain repro-ductive compatibility. The Florida Entomol. 74: 194-199.

RANKIN, M. A, AND J. C. A. BURCHSTED. 1992. The cost of migration. Annu. Rev. En-tomol. 37: 533-559.

ROGERS, C. E., AND O. G. MARTI, JR. 1994. Effects of age at first mating on the repro-ductive potential of the fall armyworm (Lepidoptera: Noctuidae). Environ. En-tomol. 23: 322-325.

SAS INSTITUTE. 1989. SAS/STAT User’s guide, version 6, 4th ed., vol. 1 and vol. 2. SASInstitute, Cary, NC.

SEN-SEONG, N. G., F. M. DAVIS, AND W. P. WILLIAMS. 1985. Survival, growth, and re-production of the fall armyworm (Lepidoptera: Noctuidae) as affected by resis-tant genotypes. J. Econ. Entomol. 78: 967-971.

SILVAIN, J. F. 1986. Use of pheromone traps as a warning system against attacks ofSpodoptera frugiperda larvae in French Guiana. Florida Entomol. 69: 139-147.

SIMMONS, A. M., AND R. E. LYNCH. 1990. Egg production and adult longevity ofSpodoptera frugiperda, Helicoverpa zea (Lepidoptera: Noctuidae), and Elasmo-palpus lignosellus (Lepidoptera: Pyralidae) on selected adult diets. Florida En-tomol. 73: 665-671.

SIMMONS, A. M., AND O. G. MARTI, JR. 1992. Mating by the fall armyworm (Lepi-doptera: Noctuidae): frequency, duration, and effect of temperature. Environ.Entomol. 21: 371-375.

SIMMONS, A. M., AND C. E. ROGERS. 1994. Fall armyworm (Lepidoptera: Noctuidae)mating: effects of age and scotophase on pre-mating time, mating incidence,and fertility. J. Entomol. Science 29: 201-208.

SNOW, J. W., AND T. C. CARLYSLE. 1967. A characteristic indicating the mating statusof male fall armyworm moths. Ann. Entomol. Soc. America 60: 1071-1074.

VICKERY, R. A. 1929. Studies on the fall armyworm in the Gulf Coast of Texas. U. S.Dept. Agric. Tech. Bull. 138. Gov. Print. Office, Wash., DC.

YOUNG, J. R., J. W. SNOW, AND A. N. SPARKS. 1968. Mating of untreated and tepa-chemosterilized fall armyworm moths. J. Econ. Entomol. 61: 657-661.

Chandler: Armyworm Symposium - ’94

411

EVALUATION OF INSECT GROWTH REGULATOR-FEEDING STIMULANT COMBINATIONS FOR MANAGEMENT OF FALL

ARMYWORM (LEPIDOPTERA: NOCTUIDAE)

L. D. C

HANDLER

1

Insect Biology and Population Management Research LaboratoryAgricultural Research Service, U. S. Department of Agriculture

Tifton, GA 31793-0748

1

Current address: USDA-ARS, R.R. 3, Brookings, SD 57006.

A

BSTRACT

Application of RH-5992 2F, a neural agonist insect growth regulator, to foliage ofcorn (

Zea mays

[L.]) and southern pea (

Vigna unguiculata

[L.]), resulted in significantlevels of fall armyworm (


[J. E. Smith]) larval control. The ad-dition of a cottonseed flour-based feeding stimulant, Konsume, at 10% of total sprayvolume to the insect growth regulator reduced the length of time needed for larvalmortality to occur compared to the insect growth regulator alone. Additionally, feed-ing damage and percentage of corn plants infested by fall armyworm was significantlyreduced using RH-5992 2F + Konsume. Residual activity of RH-5992 remained high(> 84% larval mortality at the highest evaluated rate of RH-5992) on southern peathroughout the two-week test period.

Key Words:


, insect management, insecticide additives

R

ESUMEN

La aplicación de RH-5992 2F, un agonista neural regulador del crecimiento de losinsectos, al follaje del maíz (

Zea mays

[L.]) y del guisante sureño (

Vigna unguiculata

[L.]), produjo niveles significativos de control larval del gusano trozador (

Spodopterafrugiperda

[J.E.Smith]). La adición al regulador de crecimiento de un estimulante dela alimentación a base de harina de algodón, Kosume, al 10% del volumen total de as-persión, redujo el tiempo requerido para matar las larvas en comparación con el regu-lador de crecimiento solo. Adicionalmente, el daño por alimentación de las larvas y elporcentaje de plantas de maíz infestadas por el gusano trozador fueron significativa-mente reducidos usando RH-5992 2F + Kosume. La actividad residual del RH-5992permaneció alta (>84% de mortalidad larval en la concentración más alta de RH-

5992) en el guisante sureño durante las dos semanas de prueba.

Use of phagostimulants to enhance activity of insect growth regulators against fallarmyworm (FAW),


(J. E. Smith) (Lepidoptera: Noctuidae), inthe laboratory has been reported (Chandler 1993). The mortality rate of FAW larvaeincreased significantly when they fed on leaves of southern pea,

Vigna unguiculata

(L.), that had been treated with either of two insect growth regulators (RH-5992 or di-flubenzuron), in combination with Konsume

R

, a cottonseed flour-based insect feedingstimulant. Larval mortality was increased 2 and 3 days after treatment when Kon-sume (10% of total solution) and RH-5992 were applied in combination (Chandler1993). This increase in mortality was more notable than that observed with difluben-zuron/Konsume combinations. The increased mortality during the first three days fol-lowing treatment with RH-5992 is important because it can reduce FAW related



, Vol. 77, No. 4 (1994).

FEO




412



damage sooner following treatment, which may aid acceptance of this particular typeof insect growth regulator by growers. RH-5992 interferes with the normal moltingprocess of lepidopterous larvae by acting as an agonist of insect molting hormone(Rohm and Haas Co. 1989). It has been shown to have high (> 90%) levels of activityagainst FAW larvae at concentrations of 0.001 to 1.0% active ingredient [AI] (Chan-dler et al. 1992).

The studies reported here were designed to evaluate the use of RH-5992/Konsumecombinations under simulated and actual field conditions for management of FAW.Studies were conducted to evaluate the residual effectiveness and control potential ofRH-5992, with and without the addition of the feeding stimulant, and to compare theeffectiveness of RH-5992 with thiodicarb, a standard chemical insecticide used forcontrol of FAW larvae.

M

ATERIALS

AND

M

ETHODS

Spray Table Study

RH-5992 2F (Rohm and Haas Co., Philadelphia, Pa.) was formulated in water atthe rates of 11.0 and 22.0 gm AI/ha. Both of these formulations were sprayed on south-ern peas, with and without the addition of Konsume (Fermone Inc., Phoenix, AZ) (10%of total volume) to the mixture. In addition, peas were treated with a Konsume (10%of total volume)-water mixture and with water alone. The peas were planted in 25 x61 x 5 cm rectangular plastic trays filled with potting media, and these were held ina greenhouse (24-30

°

C and 50-100% relative humidity [RH]). In the greenhouse theplants were allowed to reach the 2 leaf stage (approximately 2 weeks old) prior totreatment. On 17 May, 1993, 24 trays of peas per treatment (6 total treatments) weresprayed with the above mixtures. The trays were placed on a conveyor-driven spraytable calibrated to apply 38.2 liter per ha at 59 kg/cm

2

with a single TX-6 cone nozzlefixed 46 cm above the crop. The table was set to convey the plants at a speed of 15.2m per min, and the spray nozzle was powered by compressed air. Following treat-ment, the trays of peas were returned to the greenhouse.

Leaves were collected from the treated plants 2 h and 1, 3, 7, 10, and 14 days aftertreatment. Four trays of cowpeas were used on each collection date for each treat-ment. Each tray was designated as a separate replicate. Neonate FAW larvae were ob-tained from laboratory cultures at the Insect Biology and Population ManagementResearch Laboratory in Tifton, GA. These larvae were reared as described by Perkins(1979). The larvae were held on pinto bean diet at 24

±

1

°

C for 3 days before being ex-posed to treated leaf surfaces thus allowing all insects to reach a uniform age and size.On each leaf collection date, 30 leaves per replicate (4 replicates total per collectiondate) per treatment were placed in 30-ml plastic cups. Single 3-day-old larvae wereplaced on each leaf and the cup was capped. Cups containing larvae were held in en-vironmental cabinets in the laboratory at 24

±

1

°

C, a photoperiod of 12:12 (L:D), and50

±

5% RH. After 48 h, cups were opened and the number of living versus dead larvaewas recorded. Surviving larvae were then placed in 30-ml cups containing 10 ml ofbean diet and the number of living versus dead larvae recorded following an addi-tional 3 days (120 h after application mortality). Larvae were then disposed of.

Field Study

Field corn (

Zea mays

[L.]) was planted in August 1993 at the USDA-ARS BelflowerFarm in Tift Co., GA. Nine treatments, including an untreated control, were arranged

Chandler: Armyworm Symposium - ’94

413

in a randomized block design with four replications. Plots were 3 rows (91 cm per row)wide by 7.6 m long. Treatments consisted of RH-5992 2F applied at rates of 22.0, 45.9and 91.8 gm AI/ha with and without the addition of Konsume at 10% of the total vol-ume. A 10% solution of Konsume alone and thiodicarb (Larvin 3.2) at 45.9 gm AI/hawere also evaluated. Three treatments were made to whorl stage corn beginning 23August and continued every 10 days (final treatment on 13 September). Insecticideapplications were made with a CO

2

backpack sprayer calibrated to apply 30.6 liter perha at 79 kg per cm

2

using a TX-6 nozzle and traveling at 3.2 km/hr. Prior to and every3-5 days after initial treatment through the test period, the number of damagedplants (15 plants examined per plot) were counted. Counts were terminated on 1 Oc-tober. Damaged plants were defined as those where fresh larval feeding damage andfrass were found. The number of plants damaged per plot were converted to percent-ages for data analysis. Additionally, damage ratings were taken beginning on the sec-ond count date following treatment. Ratings consisted of examining the entire plot forFAW feeding damage on a scale of 0-5, in which 0 = no damage, 1 = 1-20% damage, 2= 21-40% damage, 3 = 41-60% damage, 4 = 61-80% damage, and 5 = 81-100% damage.

Data Analyses

Means and standard deviations were calculated for percent mortality, percentageof plants damaged, and damage ratings, both by date and as combined averages (afterinitial treatment) over the length of the experiments. Analyses of variance (PROCGLM, SAS 1985) were conducted for all data sets. For the spray table study, set leastsquare means were used to compare all possible treatment combinations. Contrastswere made between individual rates of RH-5992 with and without Konsume, betweenRH-5992 treatments combined with and without Konsume, between the untreatedcontrol and Konsume only, and between the untreated control and all other treat-ments for 48 and 120 h mortality data. For the field study, orthogonal contrasts weremade to determine whether the tested rates of RH-5992, with or without Konsume,resulted in either a linear or quadratic response in the number of damaged plants anddamage ratings per treatment. Comparisons were also made between RH-5992 withand without the addition of Konsume, Konsume alone vs the untreated control, RH-5992 vs thiodicarb, and RH-5992 vs Konsume alone.

R

ESULTS

AND

D

ISCUSSION

Spray Table Study

High levels of fall armyworm larval mortality were observed following application ofRH-5992 2F with and without the addition of Konsume to the mix (Tables 1 and 2).Mortality ranged from 5.9 to 67.5 % and from 62.5 to 98.4 %, depending upon the dateand rate of active ingredient, 48 and 120 hours after leaf collection of treated leaves,respectively. Over the entire 14-day leaf collection period, no trend in loss of RH-5992residual activity could be discerned (Tables 1 and 2). Some mortality of fall army-worm larvae was noted following feeding on foliage treated with Konsume alone.However, the highest Konsume related mortality rates (17.5 %), compared to other-treatments, were not considered to be of great importance in inflicting death to the in-sect (Table 2).

414



T

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at I

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3 D

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7 D

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10 D

ays

14 D

ays

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22.0

18.2

±

9.9

44.2

±

9.2

21.7

±

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41.7

±

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622

.6

±

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217

.5

±

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27.6

±

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9R

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±

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25.0

±

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13.7

±

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44.2

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15.8

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21.7

±

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21.0

±

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±

9.9

64.2

±

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24.2

±

8.3

67.5

±

5.7

25.0

±

7.9

20.0

±

2.7

39.5

±

20.

7R

H-5

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2F +

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.0

±

5.2

48.0

±

9.6

14.2

±

8.3

40.0

±

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.9

±

9.6

15.9

±

12.

626

.6

±

15.

5K

onsu

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8

±

1.7

3.3

±

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0.0

±

0.0

0.0

±

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±

0.0

5.0

±

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1.5

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1U

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0.0

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0 ±

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0.0

± 0.

05.

0 ±

8.0

0.8

± 3.

5

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mad

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17

May

.

Chandler: Armyworm Symposium - ’94 415

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± 7

.091

.7 ±

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± 6

.190

.0 ±

2.7

89.1

± 3

.186

.7 ±

6.1

88.4

± 5

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2F11

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.0 ±

2.0

85.0

± 8

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.7 ±

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6.1

80.8

± 1

9.7

84.2

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.8 ±

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98.4

± 1

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.5 ±

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95.0

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.495

.8 ±

3.2

84.2

± 6

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.4 ±

7.1

RH

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2 2F

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11.0

84.1

± 4

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.4 ±

6.7

79.2

± 1

1.0

88.3

± 5

.892

.5 ±

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62.5

± 1

4.2

83.3

± 1

3.1

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± 1.

717

.5 ±

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09.

2 ±

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0.0

± 0.

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5 ±

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10.0

± 7

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7 ±

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0.0

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0.0

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8.3

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42.

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1 App

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mad

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17

May

.


Analysis of variance for 48 h after leaf collection mortality indicated a significantinteraction between date and treatment (F = 7.74, df = 25, P = 0.0001). Similar resultswere obtained following analysis of variance for 120 hour after leaf collection mortal-ity (F = 3.56, df = 25, P = 0.0001). These interactions indicated that treatments re-sponded differently on each leaf collection date. Therefore, comparisons amongtreatments (least square means) were made on individual leaf collection dates. Con-trasts were then conducted on seasonal average data to determine overall effects ofthe insect growth regulator/feeding stimulant mixture on fall armyworm mortality.

Least square means resulted in significant differences in treatment comparisonsbased on time of mortality observations and length of time after treatment (Tables 3and 4). In most instances mortality from the untreated control and 10% Konsumealone treatments was significantly less than all other treatments for both 48 and 120h mortality on each leaf collection date (Tables 3 and 4). Significant increases in mor-tality caused by RH-5992 + Konsume and RH-5992 alone treatments were most oftennoted within 7 days of treatment and primarily with 48 h mortality data. Data indi-cated that 48 h readings showed an increase in mortality within the first 7 days fol-lowing treatment when Konsume was added to the insect growth regulator. Mortalityobserved after 120 h was similar among most insect growth regulator treatments. Af-ter 7 days, no increase in mortality could be attributed to Konsume in the formula-tions, but mortality rates remained high (Tables 3 and 4). RH-5992 (11.0 gms AI/ha)+ Konsume resulted in significantly less mortality 14 days after application (120 hmortality) than was noted with other RH-5992 treatments.

Contrasts conducted for 48 and 120 h after leaf collection summary data indicatedthat increasing rates of RH-5992, with and without Konsume, significantly affectedfall armyworm larval mortality. RH-5992 resulted in higher mortality at the 22.0 gmAI/ha rate than at the 11.0 gm AI/ha rate on both leaf mortality observation dates (Ta-bles 5 and 6). Also, the addition of Konsume to RH-5992 resulted in higher levels offall armyworm larval mortality, both 48 and 120 h after leaf collection, than thatachieved with RH-5992 alone, regardless of insect growth regulator active ingredientrate (Tables 5 and 6). Konsume alone resulted in significantly higher levels of mortal-ity than the untreated control, and the untreated control had significantly less larvalmortality than all of the other treatments combined 48 and 120 h after leaf collection.

Field Study

Percentage of corn plants damaged by fall armyworm prior to initial insect growthregulator treatment (23 Aug.) ranged from 3 -22% per treatment (Table 7), but no sig-nificant differences in damaged plants were observed on this date although the dataare quite variable. Damage increased in the untreated plots through 13 Sept. (Tables7 and 8). Populations of fall armyworm then decreased as indicated by the reducedpercentage of plants damaged. Damage again increased from 17 Sept. until 1 Oct. (Ta-bles 7 and 8). Fewer plants were damaged in the plots treated with RH-5992 2F at91.8 gm AI/ha mixed with 10% Konsume; percentage of plants damaged ranged from2 to 32%.

There were no significant interactions between date and treatment for percentageof plants damaged and damage ratings (F=0.87, df=88, P = 0.7728 and F=0.52, df=72,P = 0.9994, respectively). All dates were combined for orthogonal contrasts.

Increasing rates of RH-5992, both with and without the addition of Konsume,resulted in a linear response for both reduction of percentage of plants damaged andplant damage ratings caused by fall armyworm larval feeding (Tables 9 and 10). Aquadratic relationship was not indicated. The addition of Konsume to RH-5992 re-


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--1-

3-1

.36

-5.0

1*-3

.14*

-8.9

0*-3

.30*

-3.1

2*3.

RH

-599

211

.01-

4-4

.23*

-8.8

4*-4

.99*

-8.3

9*-4

.71*

-2.3

41-

5-4

.90*

-9.6

1*-3

.26*

-8.0

6*-4

.34*

-2.0

34.

RH

-599

222

.01-

6-8

.43*

-12.

86*

-5.5

6*-1

3.60

*-5

.21*

-2.8

12-

3-1

.17

-4.3

4*-3

.14*

-8.9

0*-3

.30*

-3.1

2*5.

RH

-599

2 +

Kon

sum

e11

.02-

4-4

.04*

-8.1

7*-4

.99*

-8.3

9*-4

.71*

-2.3

42-

5-4

.71*

-8.9

4*-3

.26*

-8.0

6*-4

.34*

-2.0

36.

RH

-599

2 +

Kon

sum

e22

.02-

6-8

.23*

-12.

19*

-5.5

6*-1

3.60

*-5

.21*

-2.8

13-

4-2

.87

-3.8

3*-1

.85

0.51

-1.4

20.

793-

5-3

.53*

-4.6

0*-0

.12

0.84

-1.0

51.

093-

6-7

.06*

-7.8

5*-2

.42

-4.7

0*-1

.91

0.31

4-5

-0.6

6-0

.77

1.73

0.33

0.37

0.30

4-6

-4.1

9*-4

.01*

-0.5

7-5

.21*

-0.4

9-0

.47

5-6

-3.5

3*-3

.25*

-2.3

0-5

.53*

-0.8

6-0

.78

1 *In

dica

tes

sign

ifica

nt

diff

eren

ce in

tre

atm

ent

pair

s, c

riti

cal p

oin

t fo

r al

l com

pari

son

s is

.t

3.01

>


TA

BL

E 4

. T V

AL

UE

S F

OR

LE

AS

T S

QU

AR

E M

EA

NS C

OM

PA

RIS

ON

S O

F A

LL P

OS

SIB

LE

TR

EA

TM

EN

T P

AIR

S 1

20 H

OU

R A

FT

ER

LE

AF C

OL

LE

CT

ION

MO

RT

AL

ITY

.

t-V

alu

es a

t L

eaf

Col

lect

ion

Tim

e af

ter

Trea

tmen

t1

Trea

tmen

tgm

s A

I/h

aTr

eatm

ent

Pai

rs2

Hou

r1

Day

3 D

ays

7 D

ays

10 D

ays

14 D

ays

1. U

ntr

eate

d--

1-2

-0.2

9-4

.09*

-1.1

30.

000.

41-0

.32

2. K

onsu

me

--1-

3-2

2.50

*-1

9.88

*-1

0.96

*-3

4.64

*-1

2.55

*-1

4.60

*3.

RH

-599

211

.01-

4-2

9.93

*-2

1.44

*-1

2.76

*-3

7.40

*-1

3.92

*-1

5.08

*4.

RH

-599

222

.01-

5-2

9.11

*-2

1.83

*-1

1.63

*-3

6.71

*-1

4.48

*-1

0.42

*5.

RH

-599

2 +

Kon

sum

e11

.01-

6-3

2.31

*-2

3.00

*-1

2.88

*-3

9.49

*-1

5.03

*-1

4.60

*2-

3-2

2.22

*-1

5.79

*-9

.84*

-34.

64*

-12.

96*

-14.

27*

6. R

H-5

992

+ K

onsu

me

22.0

2-4

-29.

64*

-17.

35*

-11.

63*

-37.

40*

-14.

33*

-14.

76*

2-5

-28.

83*

-17.

74*

-10.

51*

-36.

71*

-14.

89*

-10.

10*

2-6

-32.

02*

-18.

91*

-11.

75*

-39.

49*

-15.

44*

-14.

27*

3-4

-7.4

3*-1

.56

-1.7

9-2

.76

-1.3

70.

483-

5-6

.61*

-1.9

5-0

.67

-2.0

7-1

.93

4.17

*3-

6-9

.81*

-3.1

2*-1

.92

-4.8

5*-2

.48

0.00

4-5

0.81

-0.3

91.

120.

70-0

.56

4.65

*4-

6-2

.38

-1.5

6-0

.12

-2.0

9-1

.11

-0.4

85-

6-3

.19*

-1.1

7-1

.25

-2.7

8-0

.55

-4.1

7*

1 *In

dica

tes

sign

ifica

nt

diff

eren

ce in

tre

atm

ent

pair

s, c

riti

cal p

oin

t fo

r al

l com

pari

son

s is

.

t3.

01>


sulted in significantly less feeding damage than when RH-5992 was used alone (Ta-bles 9 and 10). No differences in percentages of plants damaged or damage ratingswere observed comparing RH-5992 with thiodicarb (Larvin 3.2) (Tables 9 and 10). Dif-ferences were observed when comparing plants treated with all rates of RH-5992 andthose treated with Konsume alone or with untreated plants. RH-5992 treated plantshad significantly less damage than did plants treated with Konsume alone. Plantstreated with Konsume resulted in a significant reduction in damage compared to theuntreated control. However, plants treated with Konsume alone did not provideneeded levels of economic fall armyworm control. These findings are similar to thoseobserved with the spray table test.

In conclusion, use of RH-5992 2F resulted in significant levels of fall armywormlarval control on both southern pea and field corn. Addition of Konsume (at 10% of to-tal volume) to the insect growth regulator provided significantly greater fall army-worm mortality in a shorter period of time and significantly reduced fall armywormfeeding damage compared to use of the insect growth regulator alone. These resultsfurther confirmed the laboratory findings of Chandler (1993) which indicated that theuse of a cottonseed flour-based insect feeding stimulant enhanced the activity of RH-

TABLE 5. ANALYSIS OF VARIANCE TABLE FOR 48 HOUR AFTER LEAF COLLECTION FALL AR-MYWORM LARVAE MORTALITY.

DFSum of Squares

Mean Square F Value Pr > F

Model 53 48757.842 919.959 19.94 0.0001Error 90 4151.283 46.125Corrected Total 143 52909.125

Type II

DFSum of Squares


Date 5 156.732 31.346 0.68 0.6400Rep (Date) 18 845.290 46.961 1.02 0.44811) RH-5992 22.0 vs. 11.0

Gm Ai/Ha 1 521.401 521.401 11.30 0.00112) RH-5992 + Konsume 22.0

vs. 11.0 Gm Ai/Ha 1 1982.755 1982.755 42.99 0.00013) RH-5992 + Konsume vs.

RH-5992 1 1834.876 1834.876 39.78 0.00014) Konsume vs. Untreated 1 14175.567 14175.567 307.33 0.00015) All Treatments vs.

Untreated 1 24231.177 24231.177 525.33 0.00011) Interacted with Date 5 783.937 156.787 3.40 0.00742) Interacted with Date 5 779.919 155.984 3.38 0.00763) Interacted with Date 5 1658.931 331.786 7.19 0.00014) Interacted with Date 5 3269.530 693.906 14.18 0.00015) Interacted with Date 5 5690.151 1138.030 24.67 0.0001


5992 and decreased time of larval mortality. Furthermore, spray table tests indicatedthat the residual activity of RH-5992 in a controlled environment remained relativelyhigh throughout a two-week period. These positive results demonstrated the useful-ness of insect growth regulator/feeding stimulant combinations for use in field set-tings. Further study is needed to refine insect growth regulator rates and todetermine the economic feasibility of adding feeding stimulants to insect growth reg-ulator mixtures.

ACKNOWLEDGMENTS

The author wishes to thank Lenny Atkins, Steve Hooks, Laura Abbott, LarryWalker, Wendy Tyson, and Matt Wauchope for their technical assistance in conduct-ing these studies. Richard Layton is thanked for his help in conducting the statisticalanalyses of the data. Proprietary names are necessary to report factually on available

TABLE 6. ANALYSIS OF VARIANCE TABLE FOR 120 HOUR AFTER LEAF COLLECTION FALLARMYWORM LARVAE MORTALITY.

DFSum of Squares



Type II

DFSum of Squares


Date 5 625.084 125.017 2.67 0.0267Rep (Date) 18 1000.820 55.601 1.19 0.28731) RH-5992 22.0 vs. 11.0

Gm Ai/Ha 1 1102.083 1102.083 23.57 0.00012) RH-5992 + Konsume 22.0

vs. 11.0 Gm Ai/Ha 1 980.117 980.117 20.96 0.00013) RH-5992 + Konsume vs.

RH-5992 1 425.463 425.463 9.10 0.00334) Konsume vs. Untreated 1 120032.688 120032.688 2566.58 0.00015) All Treatments vs.

Untreated 1 210735.730 210735.730 4506.03 0.00011) Interacted with Date 5 430.734 86.147 1.84 0.11262) Interacted with Date 5 429.367 85.873 1.84 0.11373) Interacted with Date 5 1526.069 305.214 6.53 0.00014) Interacted with Date 5 1039.311 207.862 5.30 0.00125) Interacted with Date 5 1239.215 247.843 5.30 0.0003


TA

BL

E 7

. PL

AN

TS D

AM

AG

ED

(%) B

Y F

AL

L A

RM

YW

OR

M L

AR

VA

E F

OL

LO

WIN

G A

PP

LIC

AT

ION

OF R

H-5

992

2F W

ITH

OR

WIT

HO

UT K

ON

SU

ME

(10%

OF T

O-

TA

L V

OL

UM

E)

TO

WH

OR

L S

TA

GE

CO

RN

.1

x ±

SD

Dam

aged

Pla

nts

(%

)/Tr

eatm

ent

Trea

tmen

tgm AI/

ha

23 A

ug

Pre

-tr

eatm

ent

26 Au

g30 Au

g2

Sep

t6

Sep

t9

Sep

t13

S

ept

17

Sep

t21

S

ept

23

Sep

t28

S

ept

1 Oct

Sea

son

al A

vera

ge

RH

-599

2 2F

91.8

15 ±

11

38 ±

828

± 6

53 ±

22

42 ±

16

31 ±

14

43 ±

20

23 ±

22

15 ±

13

13 ±

55

± 6

30 ±

18

28 ±

19

RH

-599

2 2F

45.9

12 ±

16

22 ±

11

22 ±

11

52 ±

18

50 ±

742

± 1

150

± 1

332

± 1

127

± 5

15 ±

812

± 1

532

± 1

130

± 1

8R

H-5

992

2F22

.022

± 1

358

± 1

148

± 1

855

± 2

250

± 2

840

± 3

348

± 2

932

± 2

920

± 8

22 ±

618

± 6

47 ±

30

38 ±

24

RH

-599

2 2F

+

Kon

sum

e91

.83

± 4

32 ±

11

27 ±

918

± 6

25 ±

318

± 1

617

± 4

10 ±

712

± 1

57

± 5

2 ±

310

± 1

315

± 1

2R

H-5

992

2F +

K

onsu

me

45.9

22 ±

17

28 ±

22

53 ±

20

45 ±

30

45 ±

22

25 ±

26

22 ±

21

23 ±

16

18 ±

15

17 ±

21

10 ±

927

± 3

628

± 2

3R

H-5

992

2F +

K

onsu

me

22.0

20 ±

952

± 6

48 ±

13

52 ±

19

48 ±

20

40 ±

935

± 1

828

± 1

422

± 1

822

± 1

815

± 1

828

± 1

334

± 1

9K

onsu

me

--10

± 7

48 ±

40

48 ±

26

43 ±

21

45 ±

26

58 ±

15

55 ±

26

53 ±

32

27 ±

17

20 ±

12

15 ±

15

32 ±

46

38 ±

28

Lar

vin

3.2

45.9

22 ±

17

28 ±

14

30 ±

14

55 ±

20

45 ±

26

38 ±

30

47 ±

36

28 ±

20

30 ±

25

10 ±

913

± 9

45 ±

30

33 ±

24

Un

trea

ted

--15

± 1

160

± 3

147

± 2

463

± 1

863

± 1

465

± 3

165

± 2

743

± 2

128

± 2

015

± 6

13 ±

935

± 3

543

± 2

8

1 App

lica

tion

s m

ade

23 A

ug,

3 a

nd

13 S

ept.


TA

BL

E 8

. DA

MA

GE

RA

TIN

GS R

ES

UL

TIN

G F

RO

M F

EE

DIN

G B

Y F

AL

L A

RM

YW

OR

M L

AR

VA

E F

OL

LO

WIN

G A

PP

LIC

AT

ION

OF R

H-5

992

2F W

ITH

OR

WIT

HO

UT

KO

NS

UM

E (

10%

OF T

OT

AL V

OL

UM

E)

TO

WH

OR

L S

TA

GE

CO

RN

.1 x ±

SD

Dam

age

Rat

ing/

Trea

tmen

t

Trea

tmen

tgm AI/

ha

30 Au

g2

Sep

t6

Sep

t9

Sep

t13 Sep

t17 Sep

t21 Sep

t23 Sep

t28 Sep

t1 Oct

Sea

son

al

Ave

rage

RH

-599

2 2F

91.8

2.0

± 0.

03.

3 ±

0.5

2.0

± 0.

82.

3 ±

1.0

2.8

± 1.

02.

0 ±

0.8

2.0

± 0.

82.

3 ±

1.0

1.8

± 1.

01.

3 ±

0.5

2.2

± 0.

9R

H-5

992

2F45

.92.

3 ±

0.5

3.0

± 0.

82.

0 ±

0.0

2.3

± 0.

53.

3 ±

0.5

2.8

± 1.

02.

3 ±

0.5

1.5

± 0.

62.

3 ±

1.3

1.8

± 1.

02.

3 ±

0.8

RH

-599

2 2F

22.0

2.5

± 0.

63.

3 ±

1.3

2.5

± 1.

32.

3 ±

1.7

3.0

± 1.

43.

0 ±

1.4

2.5

± 1.

02.

5 ±

1.3

2.5

± 0.

62.

3 ±

0.5

2.6

± 1.

1R

H-5

992

2F +

Kon

sum

e91

.82.

0 ±

0.0

2.0

± 0.

01.

5 ±

0.6

1.3

± 0.

51.

5 ±

0.6

1.8

± 1.

02.

0 ±

1.8

1.8

± 1.

51.

3 ±

1.0

1.3

± 1.

01.

6 ±

0.9

RH

-599

2 2F

+ K

onsu

me

45.9

2.0

± 0.

02.

8 ±

0.5

2.0

± 1.

21.

5 ±

1.7

2.3

± 1.

32.

8 ±

1.5

2.5

± 1.

32.

5 ±

1.7

1.8

± 1.

01.

8 ±

0.5

2.2

± 1.

1R

H-5

992

2F +

Kon

sum

e22

.02.

3 ±

0.5

3.3

± 0.

52.

3 ±

0.5

2.3

± 0.

52.

8 ±

1.0

2.5

± 1.

02.

5 ±

1.3

2.5

± 1.

31.

8 ±

1.7

2.0

± 0.

82.

4 ±

1.0

Kon

sum

e--

2.5

± 0.

62.

8 ±

1.0

2.3

± 1.

03.

3 ±

1.0

3.0

± 1.

43.

3 ±

1.5

2.8

± 1.

32.

8 ±

1.3

2.5

± 1.

72.

3 ±

1.0

2.7

± 1.

1L

arvi

n 3

.245

.92.

0 ±

0.0

3.3

± 1.

02.

0 ±

0.8

2.3

± 1.

03.

0 ±

1.2

3.0

± 0.

82.

3 ±

1.5

1.5

± 1.

02.

5 ±

1.0

1.5

± 0.

62.

4 ±

1.0

Un

trea

ted

--2.

5 ±

0.6

3.5

± 0.

62.

5 ±

0.6

3.3

± 1.

13.

8 ±

0.5

3.5

± 0.

63.

3 ±

1.5

2.8

± 0.

52.

5 ±

1.3

2.0

± 0.

03.

0 ±

0.9

1 App

lica

tion

s m

ade

23 A

ug,

3 a

nd

13 S

ept.

Chandler: Armyworm Symposium - ’94 423.

TABLE 9. ANALYSIS OF VARIANCE TABLE FOR PERCENTAGE OF PLANTS DAMAGED BY FALLARMYWORM LARVAE, ORTHOGONAL CONTRASTS.

DFSum of Squares

Mean Square

F Value Pr > F


Type II

DFSum of Squares

Mean Square

F Value Pr > F

Date 11 65647.737 5967.976 20.54 0.0001Rep (Date) 36 35683.951 991.221 3.41 0.00011) RH-5992-Linear 1 2467.130 2467.130 8.49 0.00382) RH-5992-Quad. 1 259.414 259.414 0.89 0.34553) RH-5992 + Konsume-Linear 1 8816.667 8816.667 30.35 0.00014) RH-5992 + Konsume-Quad. 1 326.543 326.543 1.12 0.29005) RH-5992 vs. RH-5992 +

Konsume 1 3200.000 3200.000 11.01 0.00106) Konsume vs. Untreated 1 6373.663 6373.663 21.94 0.00017) RH-5992 vs. Larvin 1 28.408 28.408 0.10 0.75478) RH-5992 vs. Konsume 1 8779.020 8779.020 30.22 0.0001

1) Interacted with Date 11 793.981 72.180 0.25 0.99352) Interacted with Date 11 3101.698 281.973 0.97 0.47343) Interacted with Date 11 750.000 68.182 0.23 0.99494) Interacted with Date 11 1899.383 172.671 0.59 0.83315) Interacted with Date 11 4729.630 429.966 1.48 0.13816) Interacted with Date 11 4102.263 372.933 1.28 0.23317) Interacted with Date 11 2743.351 249.396 0.86 0.58188) Interacted with Date 11 6784.208 616.746 2.12 0.0189

TABLE 10. ANALYSIS OF VARIANCE TABLE FOR DAMAGE RATINGS RESULTING FROMFEEDING BY FALL ARMYWORM LARVAE, ORTHOGONAL CONTRASTS.

DFSum of Squares

Mean Square

F Value Pr > F



data; however, the USDA neither guarantees nor warrants the product, and the useof the name by USDA implies no approval of the product to the exclusion of othersthat may be suitable. U.S. Department of Agriculture, Agricultural Research Service,Northern Plains Area, is an equal opportunity/affirmative action employer and allagency services are available without discrimination

REFERENCES CITED

CHANDLER, L.D. 1993. Use of feeding stimulants to enhance insect growth regulator-induced mortality of fall armyworm (Lepidoptera: Noctuidae) larvae. FloridaEntomol. 76: 316-326.

CHANDLER, L.D., S.D. PAIR, AND W.E. HARRISON. 1992. RH-5992: A new insect growthregulator active against corn earworm and fall armyworm (Lepidoptera: Noc-tuidae). J. Econ. Entomol. 85: 1099-1103.

PERKINS, W.D. 1979. Laboratory rearing of the fall armyworm. Florida Entomol. 62:87-91.

ROHM AND HAAS CO. 1989. RH-5992 insect growth regulator. Technical InformationBulletin AG-2255. 6pp.

SAS INSTITUTE. 1985. SAS/STAT User’s Guide. SAS Institute, Cary, NC.

Type II

DFSum of Squares

Mean Square

F Value Pr > F

Date 9 45.656 5.073 7.13 0.0001Rep (Date) 30 95.722 3.191 4.48 0.00011) RH-5992-Linear 1 4.513 4.513 6.34 0.01242) RH-5992-Quad. 1 0.104 0.104 0.15 0.70233) RH-5992 + Konsume-Linear 1 12.013 12.013 16.88 0.00014) RH-5992 + Konsume-Quad. 1 0.704 0.704 0.99 0.32085) RH-5992 vs. RH-5992 +

Konsume 1 5.400 5.400 7.59 0.00636) Konsume vs. Untreated 1 15.313 15.313 21.52 0.00017) RH-5992 vs. Larvin 1 0.078 0.078 0.11 0.74078) RH-5992 vs. Konsume 1 22.802 22.802 32.04 0.0001

1) Interacted with Date 9 2.363 0.263 0.37 0.94902) Interacted with Date 9 2.854 0.317 0.45 0.90913) Interacted with Date 9 1.863 0.207 0.29 0.97684) Interacted with Date 9 1.421 0.158 0.22 0.99125) Interacted with Date 9 5.517 0.613 0.86 0.56056) Interacted with Date 9 3.007 0.334 0.47 0.89427) Interacted with Date 9 4.648 0.516 0.73 0.68518) Interacted with Date 9 5.375 0.597 0.84 0.5806

TABLE 10. (CONTINUED) ANALYSIS OF VARIANCE TABLE FOR DAMAGE RATINGS RESULT-ING FROM FEEDING BY FALL ARMYWORM LARVAE, ORTHOGONAL CONTRASTS.

Hamm et al.: Armyworm Symposium - ‘94

425

FIELD TESTS WITH A FLUORESCENT BRIGHTENER TO ENHANCE INFECTIVITY OF FALL ARMYWORM

(LEPIDOPTERA: NOCTUIDAE)NUCLEAR POLYHEDROSIS VIRUS

J. J. H

AMM

, L. D. C

HANDLER

AND

H. R. S

UMNER

Insect Biology and Population Management Research LaboratoryU.S. Department of Agriculture, Agricultural Research Service

Tifton, GA 31793-0748

A

BSTRACT

The nuclear polyhedrosis virus (NPV) of fall armyworm,


(J.E. Smith), was applied in combination with Fluorescent Brightener 28 (CalcofluorWhite M2R, Tinopal LPW) to whorl-stage corn. Concentrations of NPV ranged from 5larval equivalents (1 LE = 6 x 10

9

polyhedral occlusion bodies) to 1235 LE per ha. Con-centrations of fluorescent brightener ranged from 0.1 to 5% by weight in water andthe water volume ranged from 234 to 926 liters per ha. Two days after treatment, fallarmyworm larvae were collected from the treated plants and held on bean diet to ob-serve mortality due to NPV, parasitoids, and ascovirus. The fluorescent brightener in-teracted significantly with virus concentration and with water volume to increaselarval mortality. There was no increase in mortality due to NPV as the percent fluo-rescent brightener increased beyond 1%. In the higher volumes of water, 0.25% fluo-rescent brightener resulted in the highest percent mortality due to NPV.

Cotesiamarginiventris

was the most abundant parasitoid recovered from fall armyworm inthese tests, and as the percent mortality due to NPV increased, the percent mortalitydue to parasitoids and ascovirus decreased. Thus, the total mortality was not affectedas greatly as the percent mortality due to NPV by changes in water volume or fluo-rescent brightener concentration. The reduction in mortality due to parasitoids didnot appear to be a direct effect of the fluorescent brightener on the parasitoids. How-ever, increased infectivity of the NPV and earlier mortality from NPV associated withthe fluorescent brightener resulted in more host larvae dying of NPV before the par-asitoids could complete development.

Key Words:

Spodoptera frugiperda,

nuclear polyhedrosis virus, fluorescent bright-ener, biocontrol, corn,

Cotesia marginiventris

R

ESUMEN

El virus de la polihedrosis nuclear (VPN) del gusano trozador,

Spodoptera frugi-perda

(J. E. Smith), fue aplicado en combinación con Fluorescent Brightener 28 (Cal-cofluor White M2R, Tinopal LPW) a plantas de maíz en estado vegetativo. Lasconcentraciones del VPN estuvieron en el rango de los 5 a 1235 equivalentes larvales(EL) por ha (1 EL = 6 x 10

9

cuerpos polihedrales de oclusión). Las concentraciones deFluorescent Brightener estuvieron en el rango de 0.1 a 5% por peso en agua y el volu-men del agua en el rango de 234 a 926 litros por hectárea. Dos días después del tra-tamiento las larvas del gusano trozador fueron colectadas de las plantas tratadas ymantenidas en dieta de frijoles para observar la mortalidad debida al VPN, parasitoi-des, y ascovirus. Fluorescent Brightener interactuó significativamente con la concen-tración del virus y con el volumen del agua para aumentar la mortalidad larval. Nohubo aumento de la mortalidad debido al VPN cuando el porcentaje de FluorescentBrightener aumentó a más del 1%. En los volúmenes más altos de agua, el 0.25% deFluorescent Brightener produjo el porcentaje de mortalidad más alto.

Cotesia margi-niventris

fue el parasitoide más abundantemente recobrado del gusano trozador en



, Vol. 77, No. 4 (1994).

FEO




This document was created with FrameMaker 4.0.2

426



estas pruebas y en la medida en que aumentó el porcentaje de mortalidad debido alVPN, el producido por los parasitoides y ascovirus disminuyó. De esta manera, la mor-talidad total no fue afectada tanto como el porcentaje de mortalidad debido al VPN porlos volúmenes de agua o la concentración de Fluorescent Brightener. La reducción enla mortalidad producida por los parasitoides no pareció deberse al efecto del marcadoren los mismos. Sin embargo, el incremento de la infectividad del VPN y la mortalidadtemprana debidos al virus asociado con el Fluorescent Brightener provocaron que máslarvas murieran por el VPN antes que los parasitoides pudieran completar su desa-

rrollo.

The nuclear polyhedrosis virus (SfNPV) is a naturally occurring pathogen of fallarmyworm,


(J. E. Smith), (Gardner & Fuxa 1980, Fuxa 1982).However, field tests with SfNPV have resulted in rather low levels of control of fall ar-myworm larvae (Hamm & Young 1971, Hamm & Hare 1982). In these earlier tests,the virus was not formulated with adjuvants to protect the virus from sunlight or tootherwise enhance its infectivity. Recently, however, Shapiro (1992) demonstratedthat UV protection was possible using a series of optical or fluorescent brighteners(FB). More importantly, five of the optical brighteners, including Tinopal LPW, en-hanced the infectivity of an NPV that infects gypsy moth larvae, even when the viruswas not exposed to UV irradiation (Shapiro & Robertson 1992). Later, Hamm & Sha-piro (1992) demonstrated significant enhancement of the SfNPV by Tinopal LPW inlaboratory bioassays. Because of this unique enhancement of viral infectivity for lep-idopterous larvae, a patent for the use of fluorescent brighteners in biological controlwas awarded 23 June 1992 (Shapiro et al. 1992).

The field tests reported here were conducted to determine if adding FB to theSfNPV would increase the level of control of fall armyworm larvae in whorl-stagecorn. Because parasitoids (Ashley 1986) and ascovirus (Hamm et al. 1986) contributeto the natural control of fall armyworm, the effects of SfNPV and FB on parasitoidsand ascovirus were studied also. Control of fall armyworm on corn is difficult, evenwith insecticides, because the larvae feed down into the whorl. Therefore, the insecti-cides are generally applied in the maximum amount of water that can be applied eco-nomically with ground equipment (94-468 liters per ha). Consequently, therelationship between water volume, SfNPV, and FB was also evaluated.

M

ATERIALS

AND

M

ETHODS

Materials

The SfNPV was produced in the laboratory in fall armyworm larvae. The polyhe-dral occlusion bodies (POB) were partially purified by slow and high speed centrifu-gation and suspended in 0.1 m phosphate buffer (pH 7) containing 100

µ

g/mlgaramycin and stored at 6

°

C. The virus was quantified by counting POB with aPetroff-Houser bacterial counter. Concentrations were expressed as Larval Equiva-lents (LE), the approximate number of POB produced per larva, based on 6 X 10

9

POBper LE. Fluorescent Brightener 28 (Calcofluor white M2R, Tinopal LPW) was ob-tained from Sigma Chemical Co. No other UV screens, wetting agents, or feedingstimulants were used.


427

General Procedures

Tests were conducted in whorl-stage corn in Tift Co. GA. Plots were single rows 6to 7.6 m long separated by 6 m of untreated corn on the ends and five rows of un-treated corn (4.6 m) on the sides. There were five replications of each treatment ar-ranged in randomized complete blocks. Corn plants were artificially infested in earlyseason tests conducted in May and June of 1989 and 1991. Newly hatched fall army-worm larvae from the Insect Biology and Population Management Research Labora-tory colony in Tifton, GA, were mixed with corncob grits to the desired concentration(Wiseman & Widstrom 1980) and applied to the whorl-stage corn with a pushcart ap-plicator (Sumner et al. 1992). Corn plots were sprayed 3 days after being artificiallyinfested, except for May 1991 when (due to cool weather) treatments were applied 5days after infestation. Late season tests in August and September of 1993 were nat-urally-infested.

All viruses were applied using a Ford 4000 hi-clearance tractor equipped with asingle row spray boom with a single agricultural spray nozzle and tanks pressurizedwith compressed air. Spray nozzles were changed, pressure adjusted, and tractor ve-locity set to accommodate the amounts of material applied per ha for each test. Twodays after treatment, plants were cut and brought into the laboratory. Up to 30 larvaeper plot were collected from these plants and placed individually in 30-ml plastic cupscontaining bean diet. Larvae were held for observation for 8 days.

Larvae that died the first day after collection were considered to have died from in-jury during collection and were subtracted from the number collected. After the firstday, mortality was attributed to either parasitoids, SfNPV, or ascovirus. Parasitoidswere observed to emerge from the larvae and spin cocoons. Almost all parasitoids re-covered were


(Hymenoptera: Braconidae). SfNPV was indi-

T

ABLE

1. M

EAN

PERCENT

MORTALITY

AND

STANDARD

DEVIATION

DUE

TO

NPV,

PARASI-TOIDS

,

ASCOVIRUS

,

AND

TOTAL

MORTALITY

OF

FALL

ARMYWORM

LARVAETREATED

ON

WHORL

-

STAGE

CORN

WITH

S

F

NPV

AND

FB

IN

246

LITERS

PERHA

OF

WATER

, 15

MAY

1989.

NPV Parasitoids Ascovirus Total

NPV in LE per ha

% FB Mean SD Mean SD Mean SD Mean SD

0 0 0 0 35.9 8.7 8.7 8.0 46.8 9.10 0.1 0 0 35.5 14.1 6.1 4.5 41.6 17.40 1 0 0 27.9 10.5 9.5 9.8 38.9 10.55 0 6.3 4.7 35.9 7.5 9.6 7.1 51.8 10.75 0.1 17.4 8.8 33.2 8.8 2.1 3.2 52.7 9.45 1 15.1 9.9 38.8 11.5 5.5 5.1 60.0 9.450 0 25.9 6.8 21.4 14.2 2.8 3.0 50.1 10.750 0.1 25.8 9.9 26.3 14.1 4.0 5.4 56.8 15.050 1 36.6 13.3 17.6 12.3 5.0 1.9 60.0 10.9500 0 58.9 12.0 15.1 12.0 1.5 3.4 75.5 5.2500 0.1 48.4 10.0 23.0 7.1 2.1 2.0 74.3 12.2500 1 72.4 14.7 6.8 4.2 2.0 2.0 81.2 14.2

428



cated when the larvae melted and/or contained POB typical of NPV. Ascovirus wasindicated when the larvae remained small and contained the vesicles typical of ascovi-rus.

Percent mortality was determined by dividing the number that died from eachcause by the number of larvae collected (minus the number that died the first day af-ter collection). Total percent mortality was computed by adding the mortality factors

T

ABLE

2. M

EAN

PERCENT

MORTALITY

AND

STANDARD

DEVIATION

DUE

TO

NPV,

PARASI-TOIDS

,

ASCOVIRUS

,

AND

TOTAL

MORTALITY

OF

FALL

ARMYWORM

LARVAETREATED

ON

WHORL

-

STAGE

CORN

WITH

NPV

AND

FB

IN

486

LITERS

PER

HAOF

WATER

, 12

JUNE

1989.


NPV in LE per ha

% FB Mean SD Mean SD Mean SD Mean SD

0 0 0 0 2.4 2.4 0 0 2.4 2.450 0 44.6 10.3 0 0 1.0 2.1 45.6 9.150 0.1 46.1 19.0 0 0 0 0 46.1 19.050 1 68.4 19.8 0 0 0 0 68.4 19.850 5 37.9 12.3 0 0 4.0 9.0 41.9 7.3

Fig. 1. Mean percent mortality of fall armyworm larvae on whorl-stage corncaused by NPV, parasitoids (PAR), and ascovirus (AV); treated 15 May 1989 with 4levels of NPV in 3 levels of fluorescent brightener in 246 liters per ha of water.


429

together. Means and standard deviations were calculated for each morality variable.A GLM procedure (SAS 1985) was conducted for each data set using both the percentmortality and the arcsin of the square root of the percent. Percentages are shown inthe tables, but the interactions are based on the analyses of the transformed percent-ages. Regression analyses were conducted to determine linear and quadratic effects.

Rates of Virus, Fluorescent Brightener, and Water Applied

The first test, in May 1989, consisted of 12 treatments: 0, 5, 50 and 500 LE per haof SfNPV, each applied in 0, 0.1%, and 1% FB in 246 liters per ha of water.

In the second test, June 1989, the amount of water was increased to 486 liters perha and a single level of SfNPV, 50 LE per ha, was applied in 4 levels of FB, 0, 0.1, 1,and 5 percent.

In 1991, two tests were conducted in which there was an untreated control; in allother treatments a constant amount of SfNPV in varying amounts of water and FB.SfNPV at 618 LE per ha was applied in 234 liters per ha water containing 0, 0.25, 0.5,1, and 2% FB, or in 468 liters per ha water containing 0, 0.25, 0.5, and 1% FB, or in936 liters per ha water containing 0, 0.25, or 0.5% FB. The amount of FB applied was585, 1,169, 2,338, and 4,677 g per ha. The whorl-stage corn was infested 17 May, butdue to cool, rainy weather it was not treated until 22 May, 5 days after infestationrather than 3 days as in other tests. When the test was repeated, the corn was in-fested 31 May and treated 3 June.

Fig. 2. Mean percent mortality of fall armyworm larvae on whorl-stage corncaused by NPV, parasitoids (PAR), and ascovirus (AV); treated 12 June 1989 with 50LE per ha of NPV in 0, 0.1, 1, and 5% fluorescent brightener in 486 liters per ha of wa-ter plus an untreated control.

430



In 1993, 2 tests were conducted using naturally-infested whorl-stage corn. Treat-ments were applied 27 August and 27 September with 936 liters per ha water contain-ing 0 virus and 0 FB, 124 LE in 0 FB, 124 LE in 0.25% FB, 1,235 LE in 0 FB, or 1,235LE in 0.25% FB. Thus all treatments receiving FB received 2,340 g per ha of the ad-juvant.

R

ESULTS

AND

D

ISCUSSION

The 1989 treatment means and standard deviations for the first test are shown inTable 1 and the mean percent mortality due to NPV, parasitoids, and ascovirus arepresented graphically in Fig. 1. GLM analysis showed an interaction between lineareffects of NPV concentration and linear effects of FB concentration on percent mortal-ity due to NPV. Percent mortality due to parasitoids, ascovirus, and percent total mor-tality showed only linear effects of NPV concentration. The greatest percent mortalitydue to NPV, 72.4%, occurred in the 500 LE per ha treatment with 1% FB. The greatestmortality due to NPV in a 50 LE per ha treatment was also in 1% FB. There was ageneral increase in percent mortality attributable to NPV with increasing NPV con-centration and with increasing FB concentration. However, there was a general de-crease in the percent mortality caused by parasitoids and ascovirus as the percentmortality due to NPV increased.

Treatment means and standard deviations for test 2 in 1989 are shown in Table2. The mean percent mortality due to NPV, parasitoids, and ascovirus is presented

T

ABLE

3. M

EAN

PERCENT

MORTALITY

AND STANDARD DEVIATION DUE TO NPV, PARASI-TOIDS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE TREATED ONWHORL-STAGE CORN WITH 618 LE PER HA OF NPV IN VARIOUS VOLUMES OFWATER AND CONCENTRATIONS OF FB, 22 MAY 1991.

Treatments

Water FB NPV Parasitoids Total

Liters per ha % g per ha Mean SD Mean SD Mean SD

Untreated Control 0.7 1.5 53.4 9.1 54.1 9.8234 0 0 36.9 11.7 43.0 8.7 79.9 14.7468 0 0 21.3 6.8 55.4 10.4 76.7 6.8936 0 0 36.9 5.0 41.7 9.9 78.5 7.2234 .25 585 34.7 8.7 48.0 8.0 82.7 6.8468 .25 1170 34.8 11.1 39.2 7.6 74.0 10.0936 .25 2340 29.2 13.9 58.7 17.6 87.9 9.5234 .5 1170 31.5 5.7 43.1 16.8 74.6 18.3468 .5 2340 39.2 8.3 43.3 7.8 82.5 6.2936 .5 4680 51.3 6.2 33.8 7.1 85.1 1.9234 1 2340 39.5 12.1 48.4 9.4 87.9 5.1468 1 4680 42.0 7.3 40.7 9.2 82.7 2.9234 2 4680 33.8 13.6 52.5 8.6 86.3 6.4

Hamm et al.: Armyworm Symposium - ‘94 431

graphically in Fig. 2. Because all treatments (except the untreated control) containedthe same concentration of virus, the untreated control was omitted from the GLManalysis so that virus concentration would not be a factor. Thus, the effect of FB con-centration at the given level of virus could be clearly demonstrated. GLM analysisshowed a quadratic effect of FB on percent mortality due to NPV and percent totalmortality, but no significant effect on percent mortality due to ascovirus. There was nomortality due to parasitoids in any of the virus treatments and much less mortalitydue to parasitoids in the control for this test than in the first test. An increase in theFB from 1% (4,860 g per ha) to 5% (24,300 g per ha) resulted in a decrease in percentmortality due to NPV.

The 1991 tests were designed to test both the effects of water volume and concen-tration, or amount, of FB on mortality due to NPV. Thus, the virus level remained con-stant except for the untreated control which was omitted from the analysis so thatvirus concentration would not be a factor. The treatment means and standard devia-tions are shown in Tables 3 and 4. No mortality due to ascovirus was detected in the1991 tests. Mortality due to parasitoids was much higher (53.4% in the untreated con-trol) in the 22 May test, which was treated 5 days after infestation, than in the 3 Junetest (19.7% in the untreated control) which was treated 3 days after infestation.

In the 22 May test, with the higher rate of parasitoids, the interactions betweenwater and FB were similar when FB was expressed as either percent or as g perha (Fig. 3). There were interactions between quadratic effects of water and quadraticeffects of FB for both percent mortality due to NPV and percent mortality dueto parasitoids; again, as the mean percent mortality due to NPV increased the

TABLE 4. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI-TOIDS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE TREATED ONWHORL STAGE CORN WITH 618 LE PER HA OF NPV IN VARIOUS VOLUMES OFWATER AND CONCENTRATIONS OF FB, 3 JUNE 1991.

Treatments

Water FB NPV Parasitoids Total

Liters per ha % g per ha Mean SD Mean SD Mean SD

Untreated Control 4.1 4.5 19.7 4.4 23.8 6.4234 0 0 28.5 16.2 20.3 5.3 48.8 12.7468 0 0 27.0 13.7 14.7 7.6 41.7 14.9936 0 0 33.7 10.7 15.0 11.6 48.7 10.7234 .25 585 22.7 13.1 16.8 4.1 39.5 13.4468 .25 1170 39.3 7.2 8.0 5.5 47.3 9.5936 .25 2340 61.7 16.7 9.5 4.5 71.3 14.8234 .5 1170 9.5 7.5 17.4 6.4 26.9 10.1468 .5 2340 39.9 7.5 10.1 5.7 50.0 3.2936 .5 4680 46.6 14.0 12.3 8.1 58.9 8.8234 1 2340 40.4 10.5 10.1 7.0 50.5 14.5468 1 4680 33.5 10.6 16.2 10.1 49.7 1.8234 2 4680 27.1 9.4 17.0 5.6 44.0 11.5


mean percent mortality due to parasitoids decreased. However, percent total mor-tality showed only a linear effect of FB (Fig. 4).

In the 3 June test, lower rates of parasitism interfered less with the effects of wa-ter and FB on mortality due to NPV; thus, the interactions between water and FBwere different when FB was expressed as percent than when it was expressed as g perha. When FB was expressed as percent (Fig, 5), there was an interaction between thelinear effects of water and the quadratic effects of FB on both percent mortality dueto NPV and total mortality. However, there was no significant effect of water or FB onpercent mortality caused by parasitoids. When FB was expressed in g per ha, therewas a quadratic effect of FB on both percent mortality attributable to NPV (Fig. 6)and percent mortality due to parasitoids. Again, a decrease in mortality due to para-sitoids was associated with the increase in mortality due to NPV. There was an inter-

Figure 3. Mean percent mortality of fall armyworm larvae on whorl-stage corncaused by NPV following treatment on 22 May 1991 with 618 LE per ha of NPV in 5levels of fluorescent brightener in 3 volumes of water.

Fig. 4. Mean percent total mortality (NPV and parasitoids) of fall armyworm lar-vae on whorl-stage corn, treated 22 May 1991 with 618 LE per ha of NPV in 5 levelsof fluorescent brightener in 3 volumes of water.


action between the linear effects of water and the quadratic effects of FB on totalmortality (Fig. 7).

In the 1993 tests, a high volume of water, 936 liters per ha, was used to compareeffects of 0.25% FB vs 0 FB at 3 levels of virus. The treatment means and standard de-viations are shown in Tables 5 and 6. The percent mortality due to NPV, parasitoids,and ascovirus are shown graphically in Figs. 8 and 9. The 27 August test showed aninteraction between the quadratic effects of virus and the linear effects of FB on per-cent mortality due to NPV, but only the quadratic effect of virus was noted for totalmortality. There were no significant effects on percent mortality due to parasitoidsand no mortality due to ascovirus. The 27 September tests showed quadratic effectsof virus on percent mortality due to NPV, ascovirus, and total mortality. There was a

Fig. 5. Mean percent mortality of fall armyworm larvae on whorl-stage corncaused by NPV following treatment on 3 June 1991with 618 LE per ha of NPV in 5levels of fluorescent brightener expressed as percent of 3 volumes of water.

Fig. 6. Mean percent mortality of fall armyworm larvae on whorl-stage corncaused by NPV following treatment on 3 June 1991 with 618 LE per ha of NPV in 5levels of fluorescent brightener in 3 volumes of water.


significant interaction between the linear effects of virus and linear effects of FB onpercent mortality due to parasitoids.

SUMMARY

Many factors are important to the successful control of fall armyworm with theSfNPV. First the virus must be placed where the larvae are feeding and in a concen-tration sufficient for the larvae to ingest a lethal dose. In these tests, mortality due toSfNPV increased with increasing virus concentration up to the highest rate tested,1235 LE per ha. It is apparent from these tests that increasing the volume of water,up to 936 liters per ha, helped to deliver the virus deep into the whorl of the corn plant

TABLE 5. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI-TOIDS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAE TREATED ONWHORL-STAGE CORN WITH NPV AND FB IN 936 LITERS PER HA OF WATER, 27AUGUST 1993.

Treatments

NPV Parasitoids Total

NPV in LE per ha % FB Mean SD Mean SD Mean SD

0 0 0.8 1.9 7.3 6.2 8.1 6.70 .25 0 0 10.3 4.9 10.3 4.9124 0 11.8 7.9 8.5 4.7 20.5 11.4124 .25 28.7 13.3 8.0 7.0 36.7 8.01235 0 40.7 12.1 8.7 7.2 49.4 11.61235 .25 52.6 9.8 4.9 5.1 57.5 9.2

Fig. 7. Mean percent total mortality (NPV and parasitoids) of fall armyworm lar-vae on whorl-stage corn treated 3 June 1991 with 618 LE per ha of NPV in 5 levels offluorescent brightener in 3 volumes of water.


where the larvae were feeding. The FB interacted significantly with virus concentra-tion and water volume to increase mortality caused by NPV. However, there was noincrease in mortality due to NPV as the percent FB increased beyond 1%. In highervolumes of water (468 and 936 liters per ha) 0.5 and 0.25% FB resulted in the highestpercent mortality due to NPV. Of the FB rates, expressed as weight, 2,340 g per ha in

TABLE 6. MEAN PERCENT MORTALITY AND STANDARD DEVIATION DUE TO NPV, PARASI-TOIDS, ASCOVIRUS, AND TOTAL MORTALITY OF FALL ARMYWORM LARVAETREATED ON WHORL-STAGE CORN WITH NPV AND FB IN 936 LITERS PER HAOF WATER, 27 SEPTEMBER 1993.


NPV in LE per ha % FB Mean SD Mean SD Mean SD Mean SD

0 0 .7 1.5 7.9 6.7 8.4 5.5 20.0 6.10 .25 0 0 16.5 4.3 4.2 6.1 22.9 9.1124 0 36.3 12.0 12.1 7.0 0.7 1.5 49.3 8.5124 .25 47.3 4.8 9.1 6.5 0.7 1.6 58.1 10.81235 0 69.3 8.4 10.8 4.4 1.4 3.2 82.9 6.01235 .25 84.6 4.9 0.7 1.5 0.7 1.5 86.5 5.6

Fig. 8. Mean percent mortality of fall armyworm larvae on whorl-stage corn due toNPV and parasitoids (PAR), following treatment on 27 August 1993 with 3 levels ofNPV in 2 levels of fluorescent brightener in 936 liters per ha of water.


936 liters per ha resulted in the highest percent mortality due to NPV. In general, asthe percent mortality due to NPV increased the percent mortality due to parasitoidsand ascovirus decreased. This did not appear to be a direct effect of FB on the parasi-toids. The increased infectivity of the NPV and earlier mortality of larvae due to NPVassociated with the FB resulted in death of host larvae attributable to NPV before theparasitoids could complete development. Thus, the total mortality was not affected asgreatly as the percent mortality due to NPV by changes in water volume or FB con-centration.

ACKNOWLEDGMENTS

The authors wish to thank JoAnne Denham and Lenny Atkins for their technicalassistance in conducting these studies. Richard Layton is thanked for his help in con-ducting the statistical analyses of the data. Proprietary names are necessary to reportfactually on available data; however, the USDA neither guarantees nor warrants theproduct, and the use of the name by USDA implies no approval of the product to theexclusion of others that may be suitable.

REFERENCES CITED

ASHLEY, T. R. 1986. Geographical distributions and parasitization levels for parasi-toids of the fall armyworm, Spodoptera frugiperda. Florida Entomol. 69: 516-524.

FUXA, J. R. 1982. Prevalence of viral infections in populations of fall armyworm,Spodoptera frugiperda, in southeastern Louisiana. Environ. Entomol. 11: 239-242.

Fig. 9. Mean percent mortality of fall armyworm larvae on whorl-stage corn due toNPV, parasitoids (PAR), and ascovirus (AV), treated 27 September 1993 with 3 levelsof NPV in 2 levels of fluorescent brightener in 936 liters per ha of water.


GARDNER, W. A., AND J. R. FUXA. 1980. Pathogens for the suppression of the fall ar-myworm. Florida Entomol. 63: 439-447.

HAMM, J. J., AND W. W. HARE. 1982. Application of entomopathogens in irrigation wa-ter for control of fall armyworms and corn earworms (Lepidoptera: Noctuidae)on corn. J. Econ. Entomol. 75: 1074-1079.

HAMM, J. J., S. D. PAIR, AND O. G. MARTI, JR. 1986. Incidence and host range of a newascovirus form fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctu-idae). Florida Entomol. 69: 524-531.

HAMM, J. J., AND M. SHAPIRO. 1992. Infectivity of fall armyworm (Lepidoptera: Noc-tuidae) nuclear polyhedrosis virus enhanced by a fluorescent brightener. J.Econ. Entomol. 85: 2149-2152.

HAMM, J. J., AND J. R. YOUNG. 1971. Value of virus presilk treatment for corn ear-worm and fall armyworm control in sweet corn. J. Econ. Entomol. 64: 144-146.

SAS INSTITUTE. 1985. SAS/STAT User’s Guide. SAS Institute, Cary, NC.SHAPIRO, M. 1992. Use of optical brighteners as radiation protectants for gypsy moth

(Lepidoptera: Lymantriidae) nuclear polyhedrosis virus. J. Econ. Entomol. 85:1682-1686.

SHAPIRO, M., E. M. DOUGHERTY, AND J. J. HAMM. 1992. Compositions and methods forbiocontrol using fluorescent brighteners. U.S. Patent no. 5,124,149.

SHAPIRO, M., AND J. L. ROBERTSON. 1992. Enhancement of gypsy moth (Lepidoptera:Lymantriidae) baculovirus activity by optical brighteners. J. Econ. Entomol.85: 1120-1124.

SUMNER, H. R., H. R. GROSS, AND B. R. WISEMAN. 1992. Pushcart mounted rotary ap-plicator for infesting plants with the larvae of Spodoptera frugiperda (Lepi-doptera: Noctuidae). J. Econ. Entomol. 85: 276-280.

WISEMAN, B. R., AND N. W. WIDSTROM. 1980. Comparison of methods of infestingwhorl-stage corn with fall armyworm. J. Econ. Entomol. 73: 440-442.

YOUNG, J. R. 1980. Suppression of fall armyworm populations by incorporation of in-

♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦

secticides into irrigation water. Florida Entomol. 63: 447-450.

437

A GENETICALLY-MODIFIED

BACILLUS

THURINGIENSIS

PRODUCT EFFECTIVE FOR CONTROL OF THE FALL

ARMYWORM (LEPIDOPTERA: NOCTUIDAE) ON CORN

J. N. A

LL

1

, J. D. S

TANCIL

1

, T. B. J

OHNSON

2

,

AND

R. G

OUGER

2

1

Department of EntomologyUniversity of Georgia, Athens, GA 30602

2

Ecogen Inc., Langhorne, PA 19047

A

BSTRACT

ECX9399, a variant of strain EG2348 (the active ingredient of the bioinsecticideCondor

) of

Bacillus thuringiensis

(Berliner) (Bt) subspecies

kurstaki

was developedby recombinant DNA technology by Ecogen Inc. This strain showed greater control offall armyworm,


(J. E. Smith), infestations in whorl stage corn,

Zea

mays

L., than other

Bt

products in field tests conducted in Georgia, Mississippiand Florida during 1993. Control by EC9399 was greatest in Mississippi, where a 4-day spray interval (total of 3 sprays) was used and least in Georgia, where a 7-dayschedule (total of 3 sprays) was maintained. The new genetically-modified

Bt

product



, Vol. 77, No. 4 (1994).

FEO




438



had comparable efficacy (decrease in larval number on plants and reduced defoliation)to methomyl, which was used at commercial rates as a conventional insecticide stan-dard at the 3 locations.

Key Words: Corn,


,


R

ESUMEN

El ECX9399, una variante de la cepa EG2348 (ingrediente activo del bioinsecticidaCondor*) de


(Berliner) (Bt) subespecie

kurstaki

, fue desarro-llado por Ecogen Inc. mediante la tecnología de la recombinación del DNA. Esta cepademostró mayor control de las infestaciones del gusano trozador,

Spodoptera frugi-perda

(J. E. Smith), en el maíz,

Zea mays

L., en estado vegetativo que otros productosde Bt en pruebas de campo llevadas a cabo en Georgia, Mississippi y Florida durante1993. El control con EC9399 fue mayor en Mississippi, donde fue utilizado un inter-valo de aspersiones de cuatro días (3 aspersiones en total) y menor en Georgia, dondefue mantenido un programa de siete días (tres aspersiones en total). El nuevo pro-ducto de Bt genéticamente modificado tuvo una eficacia (disminución del número delarvas por planta y de la defoliación) comparable a la del methomyl, que fue empleadoen concentraciones comerciales como un insecticida convencional estándar en los tres

lugares.

Bacillus

thuringiensis

(Berliner) (

Bt

) subspecies

kurstaki

products have generallyexhibited moderate to low effectiveness for controlling the fall armyworm (FAW),

Spodoptera

frugiperda

(J. E. Smith) (Gardner & Fuxa 1980; Krieg & Langenbruch1981; Teague 1993). Recently, products derived from new

Bt

strains have been com-mercialized, including the EG2348 strain of

Bt

subspecies

kurstaki

, the active ingre-dient in the bioinsecticide Condor

. These products have shown improved toxicity forcertain insects (Gawron-Burke & Baum 1991). EG2348 was developed by Ecogen Inc.,(Langhorne, PA 19047) utilizing natural processes for transfer of plasmids with genesencoding for production of specified insecticidal crystal proteins (Gawron-Burke &Baum 1991). Recombinant DNA (

rDNA)

technology has made it possible to improve

Bt

strains (Carlton & Gawron-Burke 1993), and recently Ecogen produced a

rDNA

modified

variant (ECX9399) of EG2348 that was more toxic to FAW in laboratory tests(T. Johnson, Ecogen, Inc., Langhorne PA, unpublished data). This study reports re-sults of 1993 field trials in 3 locations with an oil flowable formulation of ECX9399 forFAW control in corn,

Zea

mays

L.

M

ATERIALS

AND

M

ETHODS

Field experiments were conducted near Athens, GA, and Oktibbeha, MS, in Au-gust and near Groveland, FL, in November. A field corn cultivar (

DeKalb 689

) wasused in GA,

Pioneer Tropical

corn was planted in MS, and

Silverqueen

sweetcorn wasemployed in FL. Plots at the 3 locations varied from 1 to 4 rows 6 to 12 m long. A ran-domized complete block experimental design was used with 4 or 5 replications.

Spray applications were made with CO

2

sprayers mounted with full-cone spraytips and calibrated at the rate of 80 to 120 liters per ha. Three applications were madein the GA (7-day intervals) and MS (4-day intervals) tests and 4 applications (4- to 6-day intervals) were made at the FL site. In each experiment, sprays were applied dur-ing the mid-whorl stage of plant development when moderate FAW infestations were

All et al.: Armyworm Symposium - ‘94

439

present in the fields (50% or more plants infested with small larvae). Test materialsincluded Cutlass

WP (

Bt

subspecies

kurstaki

, strain EG2371), Condor

OF (

Bt

sub-species

kurstaki,

strain 2348, in an oil flowable formulation), ECX9399 OF (oil flow-able formulation), and methomyl (Lannate

LV) (see Table 1 for rates).Efficacy was determined at selected intervals during and following the spray ap-

plications by examining the plants in each plot for defoliation. In MS a visual estimateof defoliation was made, whereas, in GA and FL a 0 to 8 (GA) or 0 to 10 (FL) rating ofdefoliation and whorl injury was made, progressing from 0 to destruction of plants.Additionally, between 5 and 10 plants in each plot were examined for larvae at se-lected intervals during and after the spray period. They were categorized as small (<8mm), intermediate (>8-12 mm) and large (>12 mm). To compare the data between lo-cations, the defoliation estimates and larval counts were converted to percent controlby determining the ratio of plant injury or larval counts in the treatment versus theuntreated checks. Analysis of variance and Duncan’s new multiple range test wereconducted using a computer based statistical analysis system (SAS User’s Guide: Sta-tistics 1985).

R

ESULTS

The FAW infestations at the 3 locations were moderate to heavy. The data in Table1 demonstrate that the formulation of the genetically-modified

Bt

strain ECX9399produced control comparable to the conventional standard methomyl. Control with

Bt

was best in MS, where a 4-day spray interval was used, and least in GA, which had a7-day schedule. Larval numbers also were significantly reduced on corn treated withECX9399, but were statistically different from methomyl and Condor

in GA. In theMS trial, larval populations were similar in ECX9399 and Condor

plots, and bothwere significantly less than in the methomyl treatment. In FL, larval populationswere significantly less in ECX9399 than in Cutlass

, but not the methomyl treatment.

T

ABLE

1. E

FFICACY

OF

SELECTED

BT

INSECTICIDAL

PRODUCTS

FOR

FAW

ON

MID

-

WHORLSTAGE

CORN

IN

3

LOCATIONS

DURING

1993.

% Control

1

GA

3

MS

3

FL

3

Insecticide Rate

2

Damage Larvae Damage Larvae Damage Larvae

ECX9399 OF 1.6 61.1a 32a 94.8a 79.3a 79.1a 82.9aCondor

OF 1.6-1.07 32.8bc 0a 92.0a 77.8a -- --Cutlass

WP 1.13 -- -- -- -- 44.9b 27.1bMethomyl 1.13-0.5 55.6ab 0a 89.5a 27.4b 88.4a 98.1a

1

Means followed by the same letter within a column are not significantly different in Duncan’s new multiple range analysis (P < 0.05).

2

Rates of ECX9399 OF and Condor

OF are presented as volume (in liters) of formulated product per ha, Cut-lass

WP as weight (in kg) of formulated product per ha and methomyl (Lannate

LV) as weight (in kg) of active ingredient per ha. Condor

was used at a rate of 1.6 liter per ha in GA and 1.07 liter per ha in MS; methomyl was used at 1.13 kg per ha rate in FL and 0.5 kg per ha at GA and MS.

3

Applications in GA were made on a 7-day schedule for 3 sprays, MS was every 4 days for 3 sprays and FL was every 4 or 6 days for 4 sprays.

440



The FL results were similar to those reported by Teague (1993) for Cutlass

and meth-omyl for FAW control on sweetcorn.

The results show that recombinant DNA technology can be used to improve thetoxicity and specificity of

Bt

to insects such as the FAW. ECX9399 was superior to itsparent strain, EG2348 (Condor

), in controlling FAW populations and damage inthree locations. The fact that ECX9399 produced similar control as methomyl (one ofthe most efficacious materials available for FAW (All et al. 1986)) in the experimentsaccentuates the potential of genetically-improved

Bt

strains for insect management.

R

EFERENCES

C

ITED

A

LL

, J. N., A. JAVID, AND P. GUILLEBEAU. 1986. Control of fall armyworm with insec-ticides in north Georgia sweetcorn. Florida Entomol. 69: 598-602.

CARLTON, B. C., AND C. GAWRON-BURKE. 1993. Genetic improvement of Bacillus thu-ringiensis for bioinsecticide development, pp. 43- 61 in L. Kim [ed.], Advancedengineered pesticides. Marcel Dekker, Inc., New York.

GARDNER, W. A., AND J. R. FUXA. 1980. Pathogens for the suppression of the fall ar-myworm. Florida Entomol. 63: 439-447.

GAWRON-BURKE, C., AND J. A. BAUM. 1991. Genetic manipulation of Bacillus thuring-iensis insecticidal crystal protein genes in bacteria, pp. 237-263 in J. K. Setlow[ed.], Genetic engineering. Plenum Press, New York.

KRIEG, A., AND G. A. LANGENBRUCH. 1981. Susceptibility of arthropod species to Ba-cillus thuringiensis, pp. 837-896 in H. D. Burges [ed.], Microbial control of pestsand plant diseases 1970-1980. Academic, New York.

SAS USER’S GUIDE: STATISTICS. 1985. SAS Inst., Cary, NC. 957 pp.TEAGUE, T. G. 1993. Control of fall armyworm in sweet corn with Bacillus thuringien-

♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦

sis, 1991. Insecticide & Acaricide Tests 18: 127-128.

440



MANAGEMENT OF THE BEET ARMYWORM (LEPIDOPTERA: NOCTUIDAE) IN COTTON: ROLE OF NATURAL ENEMIES

J

OHN

R. R

UBERSON

1,3

, G

ARY

A. H

ERZOG

2

, W

ILLIAM

R. L

AMBERT

2

,

AND

W. J

OE

L

EWIS

1

1

Insect Biology and Population Management Research Laboratory United States Department of Agriculture, Agricultural Research Service Tifton, GA 31793

2

Dept. of Entomology, University of Georgia, Tifton, GA 31793

3

Current address: Dept. of Entomology, University of Georgia,P.O. Box 748, Tifton, GA 31793

A

BSTRACT

The beet armyworm,

Spodoptera exigua

(Hubner), has recently become a persis-tent and explosive pest of cotton in the southeastern United States. It is, however, at-tacked by a large and diverse complex of beneficial arthropods and pathogens thatappear capable of maintaining beet armyworm populations below economically-dam-aging levels. Disruption of this complex contributes to outbreaks of

S. exigua

. It can



, Vol. 77, No. 4 (1994).

FEO




Ruberson et al.: Armyworm Symposium - ‘94

441

also exacerbate problems with other pests because the complex of beneficial organ-isms attacking the beet armyworm is comprised of generalist species that also sup-press other pests in the cotton production system. Management of the beet armywormthrough conservation of its natural enemies, therefore, provides multiple benefits togrowers by managing other pests as well.

Key Words: Beet armyworm, cotton, biological control,

Spodoptera exigua

, parasitoid,predator

R

ESUMEN

El gusano trozador de la remolacha,

Spodoptera exigua

, recientemente se ha con-vertido en una plaga persistente y explosiva del algodón en el sureste de los EstadosUnidos; sin embargo, es atacado por un complejo grande y diverso de artrópodos útilesy patógenos que parece ser capaz de mantener las poblaciones del gusano de la remo-lacha por debajo de los niveles de daño económico. La alteración de este complejo fa-vorece la aparición de brotes del gusano trozador, pero también puede aumentar losproblemas con otras plagas porque el complejo de los organismos útiles que atacan elgusano de la remolacha está compuesto de especies generalistas que también puedensuprimir otras plagas en el sistema de producción del algodón. Por lo tanto, el manejodel gusano de la remolacha mediante la conservación de sus enemigos naturales tam-

bién ofrece beneficios múltiples a los granjeros en el manejo de otras plagas.

The beet armyworm,

Spodoptera exigua

(Hübner), is an introduced pest of numer-ous crops in the United States. It appears to be a native of southern Asia, although itsorigin is presently unclear. It was first reported in the United States with the collec-tion of specimens in Oregon and California in 1876 (Harvey 1876). The insect dis-persed across the country and was established in Florida by the late 1920s, where itwas recorded feeding only on asparagus fern, gladiolus, and grasses (Wilson 1932). Inthe years since its introduction, the beet armyworm has become progressively morepestiferous in the United States on an increasingly wide range of crop plants (seePearson 1982). Its current recorded host range in North America exceeds 90 plantspecies, including numerous important crop species such as corn, cotton, soybeans,peanuts, cabbage, tomatoes, and peppers (Pearson 1982). The bases for this apparenthost range expansion are presently unclear; the changes suggest that this insect hasconsiderable phenotypic plasticity in its host range [and likely genotypic, as is thecase with the fall armyworm,


(Pashley, pers. comm.)] and thusit may become an increasingly widespread pest in the future.

In addition to its broad host range, there are several facets of

S. exigua

’s biologythat may predispose it to being an explosive pest. First,

S. exigua

has a relatively briefdevelopmental time under field conditions (Ali & Gaylor 1991), permitting rapid cy-cling of generations. Second, it has a high reproductive capacity, with average calcu-lated fecundities ranging from 604.7 to 1724.7 eggs per female (Wilson 1934, Hogg &Gutierrez 1980, Chu & Wu 1992). A simple calculation illustrates this point. Assum-ing a population sex ratio of 1 female to 1 male, a realized field fecundity of 200 eggs(approx. 2 egg masses) per female, and restricted emigration and immigration, 99%mortality within a generation would be necessary to simply maintain the populationat a constant size. Thus, suppression of this pest requires high levels of mortality tocounterbalance its high fecundity. Third, these insects are highly mobile and are thuscapable of colonizing wide-ranging areas (French 1969, Mitchell 1979). Finally, insec-

442



ticides typically provide less than adequate control (e.g., Cobb & Bass 1975, Meinke& Ware 1978, Brewer & Trumble 1989, Wolfenbarger & Brewer 1993). This is due, atleast in part, to the insect’s innate tolerance of many insecticidal materials at recom-mended field rates. But the beet armyworm’s ovipositional and feeding biology also in-fluences insecticide efficacy. Females oviposit eggs in masses of 46 to 230 eggs (x

±

SD= 99.4

±

40.6; n = 75 field-collected egg masses; J.R.R. unpubl.), typically on the un-dersurface of leaves in the lower plant canopy. Insecticide coverage is often inade-quate in these areas, particularly after the canopy has expanded. Further, beetarmyworm larvae feed in groups through the first and second instars, then disperseas third instars (Poe et al. 1973). This feeding behavior concentrates a large propor-tion of the population into a relatively small area during the period when the larvaeare most susceptible to insecticides. Thus, to kill a sufficient number of larvae to at-tain control, the material must contact a relatively small proportion of the plant can-opy in the plant region most difficult to cover — a very difficult proposition when theplants are large and the canopy is closed.

Despite its pestiferous potential, the beet armyworm has been historically a spo-radic and minor pest of cotton in the southeastern United States (Smith 1989). In re-cent years, however, it has become a persistent and serious cotton pest in thesoutheastern and mid-southern United States, especially in regions conducting theBoll Weevil Eradication Program (e.g., Fig. 1). However, the current ubiquity and con-sistency of the outbreaks, both inside and outside of active eradication zones, suggestthat this pest has become a more widespread and serious cotton pest for reasons in-dependent of the Boll Weevil Eradication Program. However, this program likely pro-vides a ready opportunity for the beet armyworm to escape natural controls.

Fig. 1. Number of specific beet armyworm insecticide treatments applied per acreof cotton production in the state of Georgia from 1980 to 1992. “BWEP”, demarcatedby the vertical dashed lines, indicates the period when the Boll Weevil EradicationProgram was in its active phase in the state.


443

Regardless of the cause, it is critical at this juncture to devise efficacious, biorationalpest management approaches.

Natural enemies appear to be a key element in the management of the beet army-worm. In 1973, Eveleens et al. demonstrated that beet armyworm outbreaks could beinduced by applications of organophosphate insecticides in cotton. Cotton can supporta large and diverse complex of beneficial arthropods (Whitcomb & Bell 1964, van denBosch & Hagen 1966) and in production systems receiving multiple treatments ofhighly toxic materials, such as organophosphates and pyrethroids, these complexescan be seriously disrupted for the remainder of the growing season. Subsequently, inthe absence of the beneficial arthropods, production of an acceptable crop will requirecontinued, repeated use of insecticides. The Boll Weevil Eradication Program relies onwidespread, repetitive applications of organophosphates to suppress and eventuallyeliminate boll weevil populations (USDA-APHIS 1991).These treatments have a pro-found detrimental impact that releases beet armyworm populations from their natu-ral biological control agents (e.g., Wilkinson et al. 1979).

N

ATURAL

E

NEMIES

OF

THE

B

EET

A

RMYWORM

The large number of predators and parasitoids that have been found associatedwith beet armyworm eggs and larvae are listed in Tables 1 and 2. This complex of nat-ural enemies differs among various geographic regions; however, there are commonlinkages. Several parasitoid species, for example, have been found across the cottonbelt, including the braconids


,

Meteorus autographae

,

Chelo-nus insularis

, the ichneumonid

Temelucha

sp., and the tachinid

Lespesia archip-pivora

(Table 2). Their relative abundance and efficacy, however, vary among regions.Similarly, several genera of predators are shared across the cotton belt. It is notewor-thy that the most commonly encountered natural enemies of the beet armyworm in allregions are generalists that attack a variety of hosts in multiple habitats. Given thatthe beet armyworm is an introduced pest, such a pattern is to be expected in the ab-sence of specific imported biological control agents.

In addition to predators and parasitoids, several pathogens have also been recov-ered from the beet armyworm. A nuclear polyhedrosis virus has been widely reported(Oatman & Platner 1972, Eveleens et al.1973, Pearson 1982, Kolodny-Hirsch et al.1993). Fungal pathogens, however, can also be important. Wilson (1933) reported thata fungus, described at the time as

Spicaria prasina

(probably

Nomuraea rileyi

), deci-mated populations of beet armyworm larvae during wet weather. In our studies inGeorgia, we have observed larvae infected with the fungi

Erynia

sp. nr.

pieris

(identi-fied by Dr. Donald Steinkraus, Univ. of Arkansas) and

N. rileyi

. Of these two species,

Erynia

was the most commonly encountered.Despite the large number of natural enemies cataloged to date, there are few data

to demonstrate their impact on beet armyworm populations. Eveleens et al. (1973)demonstrated in California that beet armyworm outbreaks could be induced by appli-cations of organophosphate insecticides, which presumably disrupt the natural en-emy complex. They suggested that predators were the most important mortalityagents for the beet armyworm populations in their study, and that the greatest lossoccurred in the egg and early larval stages. Hogg & Gutierrez (1980) also observedhigh rates of loss for eggs and small larvae of the beet armyworm in cotton in Califor-nia and also attributed much of this loss to predators.

De Clercq & Degheele (1994) recently demonstrated in the laboratory that the na-tive predaceous pentatomid

Podisus maculiventris

can consume large numbers of allstages of beet armyworm. It is, however, particularly destructive to eggs (rangingfrom 53.5 eggs consumed during the second instar to 111.6 eggs consumed per day by

444



adult female predators) and small larvae. Also, most life stages of beet armyworm arereportedly suitable prey for predator development. These data provide a glimpse intothe possible impact of predators on beet armyworms, although

P. maculiventris

ap-pears to be only a small, and inconsistent, part of the total natural enemy complex inthe field. The overall impact of natural enemies in the field, however, is poorly delin-

T

ABLE

1. P

REDATORS

OBSERVED

IN

ASSOCIATION

WITH

BEET

ARMYWORM

EGGS

ORYOUNG

LARVAE

IN

THE

U

NITED

S

TATES

.

Taxon/SpeciesState

Association

1

Location References

Dermaptera

Labidura riparia

E, L Georgia Ruberson et al. 1994Heteroptera

Orius insidiosus

E, L Georgia Ruberson et al. 1994

Orius tristicolor

E, L California Eveleens et al. 1973; Hogg and Gutierrez 1980

Geocoris pallens


Geocoris punctipes


Geocoris uliginosus


Podisus maculiventris

L Florida Wilson 1933;Georgia Ruberson et al. 1994

Nabis roseipennis

L Georgia Ruberson et al. 1994

Nabis americoferus

E, L California Eveleens et al. 1973

Zelus

sp. E, L Georgia Ruberson et al. 1994California Eveleens et al. 1973

Sinea

sp. E, L California Eveleens et al. 1973Neuroptera

Chrysoperla carnea


Chrusoperla refilabris


Hemerobius

sp. E, L Georgia Ruberson et al. 1994Coleoptera

Collops


Notoxus calcaratus


Coccinella septempunctata

E Georgia Ruberson et al. 1994Hymenoptera

Polistes fuscatus

L Florida Wilson 1933

Solenopsis invicta

E, L Georgia Ruberson et al. 1994ArachnidaUnidentified (3 species) L Georgia Ruberson et al. 1994Unidentified California Eveleens et al. 1973

1

Stage association indicates with which stages of beet armyworm the predators were found; E = eggs and L = larvae.


445

T

ABLE

2. P

ARASITOIDS

OF

BEET

ARMYWORM

EGG

AND

LARVAE

RECORDED IN THEUNITED STATES.

Taxon/SpeciesStages

Attacked1 Location References

Diptera: TachinidaeLespesia archippivora L1-L5 California van den Bosch & Hagen

1966; Henneberry et al. 1991; Eveleen et al. 1973

Texas Harding 1976Oklahoma Soteres et al. 1984

Georgia Ruberson et al. 1993Eucelatoria armigera California van den Bosch & Hagen

1966; Henneberry et al. 1991

Eucelatoria rubentis Florida Wilson 1933; Tingle et al. 1978

Eucelatoria sp. nr. armigera California Henneberry et al. 1991Winthemia rufopicta Florida Tingle et al. 1978Archytas californiae California Eveleens et al. 1973Archytas apicifer California Henneberry et al. 1991Archytas marmoratus Georgia Ruberson et al. 1994Voria ruralis California Eveleens et al. 1973Chaetogodia monticola Hawaii Swezey 1935Gonia crassicornis Florida Wilson 1933

Hymenoptera: BraconidaeCotesia marginiventris L1-L4 California van den Bosch & Hagen

1966; Pearson 1982; Henneberry et al. 1991

Oklahoma Soteres et al. 1984Florida Wilson 1933; Tingle et al.

1978Georgia Ruberson et al. 1993

Cotesia laeviceps U.S. Krombein et al. 1979Cotesia militaris No. America Krombein et al. 1979Meteorus autographae L1-L4 Florida Wilson 1933; Tingle et al.

1978Georgia Ruberson et al. 1993Texas Harding 1976

Meteorus leviventris Texas van den Bosch & Hagen 1966; Harding 1976

Meteorus rubens California Henneberry et al. 1991Meteorus laphygmae Krombein et al. 1979

1“Stages attacked” signifies larval instars (L1-L5) and eggs (E) susceptible to parasitization by the respective parasitoids.

2Oviposits in eggs and emerges from the late larval stages.


Chelonus insularis E-L52 California van den Bosch & Hagen 1966; Eveleens et al. 1973; Pearson 1982; Henneberry et al. 1991

Texas Harding 1976Oklahoma Soteres et al. 1984

Florida Wilson 1933; Tingle et al. 1978

Georgia Ruberson et al. 1993Aleiodes laphygmae L1-L3 Georgia Ruberson et al. 1993Cremnops haemotodes California Henneberry et al. 1991Zele melea Oklahoma Soteres et al. 1984

Hymenoptera: IchneumonidaeHyposoter exiguae L1-L3 California van den Bosch & Hagen

1966; Eveleens et al. 1973; Pearson 1982; Henneberry et al. 1991

Hyposoter annulipes U.S. Krombein et al. 1979Pristomerus spinator L1-L3 California Eveleens et al. 1973;

Pearson 1982; Hen-neberry et al. 1991

Oklahoma Soteres et al. 1984Campoletis argentifrons U.S. van den Bosch & Hagen

1966Campoletis flavicincta L1-L3 Georgia Ruberson et al. 1993Campoletis sonorensis L1-L3 U.S. Krombein et al. 1979

Oklahoma Soteres et al. 1984Temelucha sp. California Pearson 1982; Hen-

neberry et al. 1991Florida Tingle et al. 1978

Nepiera fuscifemora West U.S. Krombein et al. 1979Ophion sp. Georgia Ruberson et al. 1993Therion longipes California van den Bosch & Hagen

1966; Eveleens et al. 1973Rubicundiella perpturbatrix West U.S. van den Bosch & Hagen

1966; Krombein et al. 1979Sinophorus caradrinae (?) Colorado Krombein et al. 1979

TABLE 2.(CONTINUED) PARASITOIDS OF BEET ARMYWORM EGG AND LARVAE RECORDEDIN THE UNITED STATES.

Taxon/SpeciesStages




Ruberson et al.: Armyworm Symposium - ‘94 447

eated and/or entirely unknown in the southeastern U.S. where beet armyworm prob-lems have recently been most severe.

IMPACT OF NATURAL ENEMIES ON BEET ARMYWORM POPULATIONS IN GEORGIA

We have undertaken various field studies in Georgia in an effort to characterizemortality factors and levels for beet armyworm populations.These studies have fo-cused on two areas: 1) characterization and quantification of beet armyworm parasi-toids and pathogens, and 2) determination of their impact on survival of eggs, smalllarvae, and pupae.

Larval Mortality: Impact of Parasitoids and Pathogens

Beet armyworm larvae of all ages were sampled from commercial cotton fields inGeorgia in 1992 and 1993 (see Ruberson et al. 1993 for details). Collections were madeon various dates from 15 July to 16 September in 1992 and from 24 May to 12 Octoberin 1993. Totals of 7,545 and 7,072 larvae were collected in 1992 and 1993, respectively.The parasitoids reared from these larvae (in relation to instar collected) are presentedin Table 3, with rates of parasitism by each species. The parasitism rates for the twoyears, pooled across larval instars and collection locales, were 46.8% and 40.2% in1992 and 1993, respectively. The majority of parasitism, and resultant larval mortal-ity, occurred in the early instars. In both years, C. marginiventris was the predomi-nant species, and it accounted for more of the parasitism in 1993 than it did in 1992,particularly in the second and third instars (Table 3). This contrasts with results fromCalifornia indicating that the tachinid L. archippivora and the braconid C. insulariswere the most important parasitoids in cotton and alfalfa, respectively (Henneberryet al. 1991, and Pearson 1982, respectively). Soteres et al. (1984) also found C. insu-laris to be the most common parasitoid attacking beet armyworms in alfalfa in Okla-homa. C. marginiventris, however, is the dominant parasitoid of beet armywormlarvae from pigweed in Florida (Tingle at al. 1978). Thus, C. marginiventris appearsto be the more dominant species in the eastern half of the United States, whereas C.insularis is more dominant in the west.

Cotesia marginiventris is highly attracted to plants damaged by beet armywormfeeding (e.g., Turlings et al. 1991), and this response is intensified by the clumped

Hymenoptera: EulophidaeEuplectrus plathypenae L3-L5 Florida Wilson 1933

Hymenoptera: TrichogrammatidaeTrichogramma spp. E California van den Bosch & Hagen

1966

TABLE 2.(CONTINUED) PARASITOIDS OF BEET ARMYWORM EGG AND LARVAE RECORDEDIN THE UNITED STATES.

Taxon/SpeciesStages





feeding behavior of the beet armyworm larvae on cotton plants [A. Datema (Wagenin-gen, The Netherlands), J.R.R., and W.J.L., unpubl.]. This parasitoid, therefore, ishighly-attuned to locating clusters of beet armyworm larvae. It is, however, suscepti-ble to several organophosphate and pyrethroid insecticides (Wilkinson et al. 1979, Ru-berson et al. 1993), which could limit its efficacy in conventional, chemical-intensivecotton production.

Several pathogens were also recovered from larvae collected in the field, althoughdisease did not appear to be a substantial mortality factor. The most commonly-en-countered pathogen was the fungus Erynia sp. nr. pieris (determined by Dr. DonaldSteinkraus, Univ. of Arkansas), which killed 6.2% of the larvae collected in 1992, butonly 0.3% of those collected in 1993 (there was exceptionally little rain that year). Afew specimens collected in 1992 were infected with N. rileyi, but no N. rileyi was ob-served in 1993. A nuclear polyhedrosis virus was found in 1.8% of the larvae collected

TABLE 3. PARASITISM RATES (%) IN POPULATIONS OF BEET ARMYWORM LARVAE COL-LECTED IN GEORGIA COTTON IN 1992 AND 1993. LARVAE WERE COLLECTEDFROM BARTOW, BEN HILL, DECATUR, DOOLY, LAURENS, MILLER, SEMI-NOLE, AND TIFT COUNTIES.

% Parasitism of Beet Armyworm Larval Instar1

Parasitoid 1 2 3 4 5

1992

Cotesia marginiventris 37.0 37.5 37.0 3.4 1.5Aleiodes laphygmae 0.06 0.6 0.3 0.0 0.0Meteorus autographae 4.7 10.6 7.6 3.4 0.0Chelonus insularis 0.6 0.9 0.9 2.0 0.0Lespesia archippivora 0.07 0.8 2.2 4.1 3.3Ichneumonidae2 1.0 0.4 1.3 0.3 8.2Unknown parasites 0.2 0.5 1.3 1.0 0.0Total % parasitism 43.6 51.2 50.6 14.2 13.0No. larvae collected 2977.0 2701.0 1512.0 294.0 61.0

1993

Cotesia marginiventris 35.8 58.5 63.4 2.9 0.2Aleiodes laphygmae 0.0 0.8 0.0 0.0 0.0Meteorus autographae 0.0 0.1 0.7 0.1 0.0Cardiochiles nigriceps 0.0 0.0 0.1 0.0 0.0Pristomerus spinator 0.0 0.3 0.9 0.8 0.0Lespesia archippivora 0.02 0.3 0.8 0.6 2.2Archytas marmoratus 0.0 0.0 0.03 0.5 0.5Unknown parasites 0.02 0.1 1.1 0.4 0.8Total % parasitism 35.8 60.1 67.0 5.3 3.7No. larvae collected 2914.0 1542.0 1207.0 768.0 641.0

1Instar of larvae at time of collection.2Includes Campoletis sonorensis, Pristomerus spinator, and Ophion sp.


in 1992 and in 0.1% of the larvae in 1993. In addition, a single larva infected with anascovirus (determined by Dr. John J. Hamm, USDA-ARS, Tifton GA) was collected in1992. The senior author and J.J. Hamm (USDA-ARS, Tifton, GA) found this virus tobe a poor pathogen of beet armyworm larvae in laboratory tests.

Overall parasitoid- and pathogen-related mortality from our collections rangedfrom approximately 40 to 50%. These overall rates were generally higher than thoseobserved in the California studies noted above (Pearson 1982, Henneberry et al.1991). However, Pearson (1982) did observe comparable parasitism levels for larvaeon alfalfa in the late summer and early fall in Imperial Valley. This level of mortalitycomprises a relatively high level of loss in the population, but is well below the 99%needed to maintain or suppress the pest population.

Impact of Predation on Eggs, Larvae, and Pupae.

Two studies were undertaken to examine loss of beet armyworms in the field. Thefirst examined the rate of loss for eggs and small larvae to assess loss prior to, and inthe initial periods of susceptibility to parasitization. The second study addressed theloss of beet armyworm pupae in the soil.

Egg/Larvae Predation. The study to determine egg/larval losses was conductedfrom 16 to 27 August, 1993, in cotton plots in Tift County, Georgia. Beet armywormegg masses (approximately 100 eggs each), laid on wax paper, were attached to theundersides of leaves in each of four 0.5 acre plots. Two of the plots received weekly ap-plications of conventional insecticide (the pyrethroid l-cyhalothrin) beginning the firstweek in July, whereas the other plots were untreated. Insecticide was applied in thetreated plots immediately prior to, and twice during, the experiment. Twenty-four eggmasses were placed in each plot (approximately 1 per 1000 plants; action threshold is2-3 per 100 plants). Egg masses were observed daily for hatching and for indicationsof predation. After hatching, the wax paper was removed, surviving larvae were ob-served and counted 2, 4, 6, and 8 days post-hatch, and the presence and identity ofpredators on the leaves near the larval groups were recorded.

High rates of loss were noted for egg masses exposed to predators in both thetreated and untreated cotton, although loss was faster in the absence of insecticides(Table 5). Twice as many egg masses were entirely destroyed in the untreated cotton,however, as in the treated cotton. Most of the loss occurred in the egg and early-larvalstages, as was suggested by Eveleens et al. (1973) and Hogg & Gutierrez (1980). Weattribute this loss to predator activity. Thus, survival of beet armyworms was en-hanced in the insecticide-treated plots.

More predators were observed in association with the beet armyworm eggs andlarvae in the untreated cotton than in the treated cotton (Table 4). For example, onlylarvae of the green lacewing, Chrysoperla rufilabris were found associated with beetarmyworm eggs in the treated plots, compared with 11 different predators in the un-treated plots. Thus, insecticide treatments disrupted a major portion of the beneficialarthropod complex.

Two constraints limit the general applicability of these data concerning predationof beet armyworms. First, the plots were small, and widespread recolonization oftreated plots by predators from adjacent untreated areas would be more rapid inthese plots than would be the case for large cotton fields. Second, the density of beetarmyworm egg masses placed in the plots was very low, which provided an excellentopportunity for the resident beneficial populations to eliminate them.However, thissecond point has some positive ramifications. Our data suggest that a conserved pred-ator complex is capable of greatly reducing, and perhaps eliminating, low populationsof the beet armyworm. Thus, the predator complex may be invaluable for eliminating


incipient beet armyworm populations, at least until sufficient egg and larval popula-tions are present in the field to outstrip the predators’ capacity to consume a substan-tial majority of the eggs and larvae.

Pupal Mortality. We examined loss in the pupal stage by placing ultimate-instarbeet armyworm larvae under a styrofoam cup, with an opened, 30-ml diet cup con-taining artificial diet and a larva on the soil surface. Larvae were placed in two plots(100 per plot) of each of two treatments, insecticide-treated and unsprayed. A styro-foam collar (9 cm diam) into which the covering cup fit snugly was forced into theground until its rim was level with the soil surface (about 6 cm). This prevented es-cape of the larvae because beet armyworms pupate in the upper 2-3 cm of soil. Theopened diet cup with larva was then placed inside the collar and a styrofoam cup,which fit snugly into the collar, was placed over the cup with the insect. After the lar-vae had entered the soil and pupated, the covering cups were removed to expose thepupation sites to biotic and abiotic conditions in the field. Twenty additional cups andlarvae were set up, with the covering cups left in place to trap the adult moths atemergence. These sentinel larvae were observed every day for adult emergence. When

TABLE 4. PREDATORS, AND THEIR FREQUENCY, FOUND IN ASSOCIATION WITH BEET AR-MYWORM EGGS AND LARVAE IN TREATED (PYRETHROID INSECTICIDE) ANDUNTREATED COTTON (16-27 AUGUST 1993; TIFT. CO., GEORGIA).1

Predator Taxon/Species Untreated Cotton Treated Cotton

HeteropteraOrius insidiosus E (5, 8) L (2, 3) E (0, 0) L (3, 3)Geocoris punctipes E (2, 3) L (3, 3) E (0, 0) L (0, 0)Geocoris uliginosus E (1, 1) L (1, 1) E (0, 0) L (0, 0)Nabis roseipennis E (1, 1) L (2, 3) E (0, 0) L (0, 0)Zelus sp. E (1, 2) L (1, 1) E (0, 0) L (0, 0)Posisus maculiventris E (1, 1) L (1, 1) E (0, 0) L (0, 0)

DermapteraLabidura riparia E (1, 1) L (2, 4) E (0, 0) L (0, 0)

ColeopteraCoccinella 7-punctata E (0, 0) L (1, 1) E (0, 0) L (1, 1)

NeuropteraChrysoperla rufilabris E (2, 2) L (5, 7) E (2, 2) L (0, 0)Hemerobius sp. E (1, 1) L (0, 0) E (0, 0) L (1, 2)

DipteraSyrphid E (0, 0) L (1, 1) E (0, 0) L (0, 0)

HymenopteraSolenopsis invicta E (3, 24) L (3, 16) E (0, 0) L (3, 21)

AraneidaSpiders E (1, 1) L (1, 1) E (0, 0) L (0, 0)

Totals E (19, 45) L (23, 42) E (2, 2) L (8, 27)

1E = egg masses, L = larval clutches. The numbers in parenthesis after each letter are, respectively, 1) thenumber of egg masses or larval clutches on which the predator was found, and 2) the total number of the pred-ator taxon observed in association with beet armyworm eggs or larvae.


adult emergence was complete in the sentinel cups, all pupation sites were excavated,and the status of the pupal remains determined.

Loss of pupae was surprisingly high in both treatments. Only 42.3% ± 2.12 (SD) ofthe pupae produced adult moths in the treated plots, compared with 21.0% ± 0.28 pu-pae surviving to adult emergence in the untreated plots. Thus, loss in the untreatedplots was twice that observed in the insecticide-treated plots, although both treat-ments sustained fairly high mortality.

Much of the loss observed in the experiment may be attributable to activity of im-ported fire ants, Solenopsis invicta. Fire ants were abundant in both fields, althoughthey appeared to be more common in the untreated cotton than in the treated plots.Fire ants were observed removing pupal parts from pupation sites during the exper-iment; such sites afterward yielded no signs of pupal remains when excavated.

CONCLUSIONS

Although some of the results reported above are preliminary, summing up all ofthe mortality factors and their impacts yields a mortality rate in excess of 99% in un-treated cotton. This suggests that the natural enemy complex functioning in cottonhas the capacity to suppress beet armyworm populations. This conclusion, suggestedby the California research reviewed above, points to the necessity of conserving thenatural enemies for effective suppression of the beet armyworm. The completion ofthe active phase of the Boll Weevil Eradication Program in most of Georgia has pro-vided the cotton production system an enormous opportunity to utilize natural ene-mies. In the absence of early-season applications of organophosphate insecticides tocontrol the boll weevil, the natural enemy populations are able to increase in the cot-ton crop, and use of selective insecticides on a strictly as-needed basis will permitgrowers to realize the full benefits of these natural enemies. Under this system, thebeet armyworm should not be a serious pest, except in cases where other pest controlapproaches disrupt the complex of resident beneficial organisms. Growers will reapbenefits, however, beyond the natural control of beet armyworm populations. Thecomplex of natural enemies that attacks the beet armyworm is comprised of general-ists that will also provide some level of suppression of other arthropod pests in thesystem, as well, and benefit the overall cotton insect management program.

TABLE 5. LOSS OF BEET ARMYWORM EGG MASSES, EGGS AND LARVAE IN TREATED ANDUNTREATED COTTON (MEAN ± SD; 16-27 AUGUST, 1993.)

No. Egg Masses Remaining No. Larvae Remaining/Egg Mass

Days of Exposure Treated Untreated Treated Untreated

0 24 ± 0.0 24 ± 0.0 97.0 ± 9.07 100.5 ± 9.01H1+2 23.0 ± 1.4 15.0 ± 4.2 18.6 ± 18.1 18.2 ± 13.4H+4 17.0 ± 0.0 10.0 ± 2.8 15.1 ± 14.6 13.7 ± 11.7H+6 9.0 ± 1.4 4.5 ± 0.7 11.3 ± 15.5 6.0 ± 3.8H+8 4.0 ± 1.4 0.5 ± 0.7 3.5 ± 2.8 1.0 ± 0.0

1“H” refers to hatch. Thus “H+2” means 2 days after egg hatch.


ACKNOWLEDGMENTS

We appreciate the assistance of Eddie McGriff (Decatur Co.), Mark Mitchell (Sem-inole and Miller Cos.), Jack Wall (Dooly Co.), and Mark Crosby (Laurens Co.) in locat-ing fields for larval collections. Ray Wilson, Daniel West, Elizabeth Cravey, WesShiver, and Russ Ottens helped collect larvae and assisted with various aspects of theexperiments. We greatly appreciate the determinations of the parasitoid species byDrs. R. W. Carlson (Ichneumonids), E. E. Grissell (Chalcididae), P. M. Marsh (Bra-conids), and N. E. Woodley (Tachinids). The comments of Drs. Robert M. McPherson(Univ. of Georgia) and Robert Lynch (USDA-ARS) on the manuscript are also appre-ciated.

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BREWER, M. J., AND J. T. TRUMBLE. 1989. Field monitoring for insecticide resistancein beet armyworm (Lepidoptera: Noctuidae). J. Econ. Entomol. 86: 1520-1526.

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454



BEET ARMYWORMS (LEPIDOPTERA: NOCTUIDAE) IN NORTHEAST LOUISIANA: OBSERVATIONS ON AN

UNCOMMON INSECT PEST

E. B

URRIS

, J.B. G

RAVES

, B.R. L

EONARD

,

AND

C.A. W

HITE

Louisiana State University Agricultural Center, Baton Rouge, Louisiana

A

BSTRACT

Outbreaks of beet armyworm,

Spodoptera exigua

(Hubner), in cotton in Louisianaoccurred in 1983, 1988, 1992 and 1993. The outbreaks generally followed historic pat-terns observed in other locations, i.e., (l) local endemic populations developed rapidlyfor one or two generations when climatic conditions were favorable and (2) biologicalcontrol organisms were suppressed by pesticides. Outbreaks of beet armyworm inLouisiana usually are less severe than in other southeastern states, because popula-tions are usually lower and they occur in the latter part of the growing season. In1993, beet armyworms infested more ha and caused higher levels of economic damagein Louisiana than in prior years. Insecticide screening tests conducted in 1993 indi-cated that Pirate (AC 303630) was more efficacious compared to all other insecticides.Beet armyworm larvae (2nd-3rd instar) were confined to Monsanto transgenic

Bacil-lus thuringiensis

(Bt) cotton (line 1076) and untreated Coker 312 in the laboratory. Nosignificant (P

≤

0.05) differences in leaf area consumed, mortality or pupal weightswere detected.

Key Words: Beet armyworm,

Spodoptera exigua

, cotton, insecticides

R

ESUMEN

Brotes del gusano trozador de la remolacha,

Spodoptera exigua

(Hubner),ocurrieron en el algodón de Louisiana en 1983, 1988, 1992 y 1993. Los brotesgeneralmente siguieron los patrones históricos observados en otras localidades, o sea,que (1) las poblaciones locales endémicas se desarrollaron rápidamente en una o dosgeneraciones cuando las condiciones climáticas fueron favorables y (2) los enemigosnaturales fueron eliminados por los pesticidas. Los brotes del gusano trozador de laremolacha en Louisiana usualmente son menos severos que en otros estados delsureste, porque sus poblaciones son menores y aparecen al final de la estación. En1993, los gusasnos trozadores de la remolacha infestaron más hectáreas y causaronmás dano económico en Louisiana que en los anos anteriores. Las pruebas de tamizajede insecticidas llevadas a cabo en 1993 indicaron que Pirate (AC 303630) fue máseficaz en comparación con otros insecticidas. En el laboratorio fueron confinadaslarvas del gusano trozador de la remolacha (2

°

y 3

er

instar) con algodón Monsantotransgénico de


(Bt) (línea 1076) y Cocker 312 sin tratar. Nofueron detectadas diferencias significativas (P

≤

0.05) en el area de hojas consumida,

mortalidad o peso pupal.

Beet armyworms, Spodoptera exigua (Hubner), were introduced into the westernU.S. in the late 19th century (Chittenden 1902). They dispersed rapidly across theU.S. and, by the late 1920’s, they were recognized as a sporadic pest of cotton in theSoutheastern U.S. (Wilson 1932).

The earliest preserved beet armyworm specimens from Louisiana in the LSU De-partment of Entomology museum were collected in Baton Rouge. One specimen wascollected from broadbean on 6 January 1932 and another from turnip on 29 Septem-ber 1937 (Joan B. Chapin, Dept. of Entomology, LSU Agricultural Center, BatonRouge, personal communication). Light trap collections of noctuids in Baton Rouge



, Vol. 77, No. 4 (1994).

FEO




Burris et al.: Armyworm Symposium - ‘94

455

from the years 1957 through 1960 revealed that beet armyworm moths were capturedfrom 27 March through 6 December (Chapin & Callahan 1967). Beet armyworm lar-vae were collected from cole crops (Brassicae) in mid-December (date unknown) in Ba-ton Rouge (Oliver & Chapin 1981).

Outbreaks of beet armyworm are reported to be sporadic, occurring roughly every2-5 years (Rabb & Kennedy 1979). These outbreaks typically occur one or two gener-ations after favorable climatic conditions are accompanied by suppression of biologi-cal control agents by pesticides used for control of other pests.

In Florida, no evidence of hibernation has been observed, and all stages of the in-sect are found throughout the year (Smith 1993). The ability of beet armyworms tooverwinter is limited by frost kills of host plants and by temperatures below 10

°

C(Butler et al. 1976). Whether or not the beet armyworm hibernates and/or overwin-ters in Louisiana is unknown. Average daily minimum temperatures (1931-1980) forthe Northeast Research Station at St. Joseph for January, February, March, are re-spectively 3.0, 4.2 and 7.8

°

C (Thompson et al. 1983). Therefore, during most years,cold temperatures in Northeastern Louisiana may cause high mortality of beet army-worms.

Other deterrents to population growth of beet armyworms in Louisiana may exist.For example, they are polyphagous feeders that damage vegetable crops, ornamentalsand field crops, and commercial production of ornamentals and vegetable crops withinthe major cotton production regions in Louisiana is limited.

Several private agricultural consultants have annually reported problems withbeet armyworms in isolated fields in Northeast Louisiana. This suggests a need forstudies of migration and/or overwintering biology of beet armyworm in this area.Their scouting records show armyworm egg masses (fall armyworm,

Spodoptera fru-giperda

(J.E. Smith) or beet armyworm) were found in August of 1980, 1983 and 1985,and in July of 1988 and 1990. The 1988 beet armyworm outbreaks in Louisiana oc-curred within two days of severe outbreaks in Alabama (Ed Jones Consulting Service,Rayville Louisiana, personal communication). In 1993, the first beet armyworm eggmasses were observed in June (Ray Young, Young Consulting Service, Wisner, Louisi-ana, personal communication).

Beet armyworm outbreaks in Louisiana have generally followed the patterns ob-served in other major cotton producing states in the Southeastern U.S [Alabama(Smith 1985, 1989a, 1989b, 1993, 1994), Georgia and Mississippi], except that thepercent of the total cotton ha infested is usually lower (Head 1989-1992). An exceptionoccurred in 1993 in Louisiana, when 242,820 of the 354,113 ha harvested (69%) wereinfested and economic injury occurred on about 80,940 ha (23% of harvested ha, Wil-liams, 1994). Reports from Alabama indicated 73% of the ha planted to cotton were in-fested with beet armyworm in 1993 with 26% of harvested ha suffering economicdamage (Williams 1994). Williams (1994) also reported that 82% of the cotton(546,345 ha) in Mississippi was infested with beet armyworms in 1993 and 69% re-ceived one or more insecticide applications for beet armyworm control.

The outbreaks of beet armyworm in 1983 and 1992 in Louisiana provided an op-portunity to evaluate the efficacy of several insecticides. In 1983, the pyrethroidscypermethrin (0.0670.112 kg AI/ha), flucythrinate (0.09 kg AI/ha) and tralomethrin(0.021 kg AI/ha) failed to provide satisfactory control of the pest. However, maximumlabeled rates of sulprofos (1.68 kg AI/ha) and profenofos (1.12 kg AI/ha) as well asmethomyl (0.5 kg AI/ha) and thiodicarb (0.67 kg AI/ha) provided satisfactory control(Burris 1983). In 1992, sulprofos (1.68 kg AI/ha), methomyl (0.51 kg AI/ha), thiodicarb(1.0 kg AI/ha) and Pirate (AC 303630) (0.23-0.39 kg AI/ha) were the only insecticidesthat significantly reduced numbers of beet armyworm larvae (Graves 1993a, 1993b,1993c). However, Pirate was the only insecticide that provided >90% control. Mix-

456



tures of fenvalerate (0.17 kg AI/ha) + profenofos (0.56 kg AI/ha) and fenvalerate (0.17kg AI/ha) + amitraz (0.28 kg AI/ha) also significantly reduced beet armyworm larvaldensities, but control by these treatments was only about 70%.

The widespread beet armyworm infestations and numerous field control failuresthat occurred in 1993 in Louisiana prompted research to re-evaluate the efficacy of se-lected insecticides and to determine the effectiveness of transgenic cotton containingthe Bt toxin on development of this pest.

M

ATERIALS

AND

M

ETHODS

Insecticide Screening Tests.

Northeast Research Station.

Cotton (DPL 51) was planted on 8 May with plots con-sisting of four 19.8m rows with 102 cm centers. Treatments (see Table 1) were ar-ranged in a randomized complete block design and replicated four times. Applicationswere made with a high clearance sprayer calibrated to deliver 93.5 liters total sprayper ha through Teejet X-12 hollow cone nozzles (two per row) at 3.9 kg/cm

2

. For Test1, insecticide treatments were applied 29 July and 2 and 16 August. On 14 August, vi-sual ratings were used to estimate the level of foliage feeding by the beet armyworm.

T

ABLE

1. E

VALUATION

OF

SELECTED

INSECTICIDES

AGAINST

BEET

ARMYWORM

ON

THE

N

ORTHEAST

R

ESEARCH

S

TATION

—1993.

Treatment Rate/ha (kg AI) Visual

1

RatingsPercent

2

Control

Test 1UTC -- 3.0a 0AC 303630 0.17 0.5c 83AC 303630 0.22 0.0d 100AC 303630 0.28 0.5c 83

l

-cyhalothrin 0.045 3.0a 0Thiodicarb 0.31 1.0b 67Thiodicarb 1.01 0.5c 83AC 303630 +

l

-cyhalothrin 0.28 + 0.031 0.5c 83AC 303630 + amitraz 0.28 + 0.28 0.5c 83

Test 2UTC -- 3.0a 0l-cyhalothrin 0.03 2.4ab 20Profenofos 1.12 1.9ab 37Profenofos + thiodicarb 0.75 + 0.30 1.3ab 57Profenofos +

l

-cyhalothrin 0.45 + 0.028 2.5a 17Profenofos + Bt (Design 100 WP) 0.45 + 0.83

3

2.4ab 20Profenofos + methomyl 0.56 + 0.17 0.6b 80

1

Means followed by same letter do not significantly differ (P

≤

0.05; Duncans MRT). For visual ratings: 0 (nofeeding damage), 1 (feeding damage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 andmiddle 1/3 of the plant) or 3 (feeding damage throughout the plant).

2

Compared to UTC.

3

Formulated product.

Burris et al.: Armyworm Symposium - ‘94

457

For Test 2, treatments were applied on 19, 23, 27 July and 2, 6 and 17 August. Visualratings of beet armyworm damage to foliage were made on 19 August. A visual defo-liation rating for each plot was scored as follows: 0 (no feeding damage), 1 (feedingdamage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 and mid-dle 1/3 of the plant), or 3 (feeding damage throughout the plant).

Macon Ridge Branch.

Cotton (Stoneville 887) was planted on 2 June with plotsconsisting of four 15.2m rows with 102 cm centers. Treatments (see Table 2) were ar-ranged in a randomized complete block design and replicated four times. Applicationswere made with a high clearance sprayer through Teejet X-8 hollow cone nozzles (2per row) at 3.2 kg/cm

2

.For Test 1, insecticide treatments were made on 4, 9, 20 and 31 August with 56.1

liters total spray per ha. Visual ratings of beet armyworm damage to all plots weremade on 8 September using the rating system previously described. For Test 2, insec-ticide treatments were made on 30 August with 93.5 liters total spray per ha. Theplots were sampled 7 days after treatment using a shake cloth. Two samples weretaken between the two center rows in each plot (total of 1.8 meters per plot). Plantswere vigorously shaken on both rows to dislodge all larvae, which were then counted.

Effects of Transgenic Bt Cotton on Beet Armyworm.

A randomized block experimental design with four replications was used to com-pare the development of beet armyworms on cotton plants expressing the

Bacillusthuringiensis

(Bt) toxin (Monsanto line 1076) or the nontransgenic parent (Coker

T

ABLE

2. E

VALUATION

OF

SELECTED

INSECTICIDES

AGAINST

BEET

ARMYWORM

ON

THE

M

ACON

R

IDGE

B

RANCH

OF

THE

N

ORTHEAST

R

ESEARCH

S

TATION

—1993.

Treatment Rate/ha (kg AI)Efficiency

RatingPercent

2

Control

Test 1 Visual Rating

1

UTC -- 3.0a 0AC 303630 0.22 0.1c 97AC 303630 0.34 0.3c 90AC 303630 0.45 0.0c 100AC 303630 + methomyl 0.22 + 0.14 0.0c 100

l

-cyhalothrin 0.03 2.3b 23Profenofos 1.12 2.6ab 13

Test 2 Larvae/1.8mUTC -- 9.5a 0AC 303630 0.28 1.2b 87Bt (Javelin 100WG) 1.68

3

5.0ab 47Thiodicarb 0.45 7.6a 20Thiodicarb 0.90 5.6ab 18Methomyl 0.67 7.8a 18Chlorpyrifos 1.12 5.9ab 38

1

Means followed by same letter do not significantly differ (P

≤

0.05; Duncans MRT). For visual ratings: 0 (no feeding damage), 1 (feeding damage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 and middle 1/3 of the plant) or 3 (feeding damage throughout the plant).

2

Compared to UTC.

3

Formulated product.

458



312). Seed for both genotypes was supplied by Monsanto Company (AgriculturalProducts, 800 North Lindbergh Boulevard, St. Louis, MO 63167) and planted 17 Mayin plots four 9.2m rows with 102 cm centers. All plots received an in-furrow treatmentof PCNB plus etridiazole (1.40 kg AI/ha) plus acephate (0.84 kg AI/ha) at planting. Vi-sual rating of defoliation were made on 2 August using the system previously de-scribed.

A laboratory experiment was conducted to further examine the effects of trans-genic Bt cotton on beet armyworm. Newly hatched aggregates of beet armyworm lar-vae were collected from several fields at the Northeast Research Station on 13 Augustand transported to the laboratory. Ten leaves per plot were randomly collected fromthe second and third position below the terminal from transgenic Bt cotton and Coker312 cotton plants. Each leaf was placed in a petri dish and five beet armyworm larvae(50 per plot) were placed in each dish. The petri dishes were covered and larvae wereallowed to feed for 72 h. Leaf area was determined for each leaf at the beginning andend of the experiment using a LiCor

, (Li-3100) Area Meter (Lincoln, Nebraska). Sur-viving larvae were transferred to a petri dish containing fresh leaves collected fromthe same plots as previously described. The experiment was terminated when larvaepupated. Percent pupation and pupal weights were determined.

R

ESULTS

AND

D

ISCUSSION

Insecticide Screening Tests.

Pirate (AC303630) was the only insecticide among those evaluated that consis-tently provided satisfactory control of beet armyworm larvae. Applications of Pirateat rates of 0.17-0.45 kg AI/ha resulted in 83-100% control (Tables 1 and 2) at both lo-cations of the Northeast Research Station. Similar control was observed at the sameapplication rate (0.28 kg AI/ha) using two different efficacy ratings (83% control usingvisual ratings, Test 1, Table 1 versus 87% control using shake cloth, Test 2, Table 2).In all tests and at every rate tested Pirate, either alone or in combination with otherinsecticides, significantly (P

≤

0.05) decreased defoliation. Also, significantly (P

≤

0.05)fewer live larvae were observed than in the untreated plots or the plots treated withl-cyhalothrin, profenofos, methomyl or thiodicarb at low rates (0.31 and 0.45 kg AI/ha). Thiodicarb at high rates (0.9 and 1.01 kg AI/ha) resulted in 41 and 83% control,respectively (Tables 1 and 2). Chlorpyrifos at 1.12 kg AI/ha only provided 38% control(Table 2).

Transgenic Cotton Evaluations.

Natural infestations of beet armyworm were present in all field plots. The visualobservations of damaged leaves on 2 August indicated no significant (P

≤

0.05) differ-

T

ABLE

3. E

VALUATION

OF

TRANSGENIC

B

T

COTTON

FOR

BEET

ARMYWORM

CONTROL

ONTHE

N

ORTHEAST

R

ESEARCH

S

TATION—1993.

TreatmentPercent

PupatingPupal Weight

(g)Leaf area

(% Consumed) Visual Ratings1

Bt Line 1076 18a 0.05718a 49.35a 2.2aCoker 312 31a 0.05458a 49.35a 2.4a

1Means followed by same letter do not significantly differ (P≤05; Duncan’s MRT). For visual ratings: 0 (no feeding damage), 1 (feeding damage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 and middle 1/3 of the plant) or 3 (feeding damage throughout the plant).

Burris et al.: Armyworm Symposium - ‘94 459

ences for beet armyworm damage between nontransgenic cotton and transgenic cot-ton plants (Table 3). However, leaf area measurements were significantly (P≤0.05)higher for Bt line 1076 than for Coker 312 parent line on 16 August (data not pre-sented). When beet armyworm larvae were confined to Bt line 1076 and Coker 312parent line leaves in the laboratory, there was no significant (P≤0.05) difference in leafconsumption, mortality (% pupating) and pupal weights (Table 3). The Bt endotoxinpresent in line 1076 appeared to have little or no effect on beet armyworm develop-ment.

REFERENCES CITED

BUTLER, G. D., JR., S. L. POE, G. L. CRANE, C. NELLINGER, AND D. CLARK. 1976. A com-puter model to evaluate chemical control of beet armyworms in chrysanthe-mum ranges in Florida. Florida Entomol. 59:93-100.

BURRIS, E. 1983. Evaluation of cotton insecticides in Louisiana. Proceedings Missis-sippi Entomological association. Vol. 3:14

CHAPIN, J. B., AND P. S. CALLAHAN. 1967. A List of the Noctuidae (Lepidoptera, In-secta) collected in the vicinity of Baton Rouge, Louisiana. The Proceedings ofthe Louisiana Academy of Sciences, Vol. 30:39-48.

CHITTENDEN, F. H. 1902. Some insects injurious to vegetable crops. USDA Div. of En-tomol. Bull. 33 N.S. pp. 37-46.

GRAVES, J. B., B. R. LEONARD, AND P. A. CLAY. 1993a. Evaluation of selected insecti-cide mixtures against late season populations of bollworm, tobacco budwormand beet armyworm. Insecticide and Acaricide Tests 18:223.

GRAVES, J. B., B. R. LEONARD, AND P. A. CLAY. 1993b. Evaluation of selected insecti-cide mixtures against late season populations of bollworm, tobacco budwormand beet armyworm. Insecticide and Acaricide Tests 18:223.

GRAVES, J. B., B. R. LEONARD, AND P. A. CLAY. 1993c. Evaluation of Pirate against lateseason populations of bollworm, tobacco budworm and beet armyworm. Insec-ticide and Acaricide Tests 18:224.

HEAD, R. B. 1989-1992. Cotton insect losses, in Proceedings, Beltwide Cotton Prod.Res. Conf., National Cotton Council, Memphis, Tenn.

OLIVER, A. D., AND J. B. CHAPIN. 1981. Biology and illustrated key for the identifica-tion of twenty species of economically important noctuid pests. Louisiana Agric.Expt. Stn. Bull. No. 733.

RABB, R. L., AND G. G. KENNEDY. 1979. Movement of highly mobile insects: conceptsand methodology in research, pp. 386-393 in Proceedings of a Conference,“Movement of Selected Species of Lepidoptera in the Southeastern UnitedStates,” Raleigh, North Carolina.

SMITH, R.H. 1985. Fall and beet armyworm control in Proc. Beltwide Cotton Prod.Res. Conf., National Cotton Council, Memphis, TN.

SMITH, R. H. 1989a. Experiences with beet armyworm control in cotton in 1988, pp.273-275 in Proceedings Beltwide Cotton Prod. Res. Conf., National CottonCouncil, Memphis, Tenn.

SMITH, R. H. 1989b. Beet armyworms on cotton. Alabama Cooperative Extension Ser-vice, Auburn University, Alabama, Circular Anr-538.

SMITH, R. H. 1993. Managing cotton to avoid beet armyworms. Auburn University, Al-abama, Newsletter 5, pp. May 6, 1993.

SMITH, R. H. 1994. Beet Armyworm: A costly caterpillar. Proceedings Beltwide CottonProd. Res. Conf., National Cotton Council, Memphis, Tenn. (In Press)

THOMPSON, R. C., R. A. MULLER, AND S. H. CRAWFORD. 1983. Climate at the North-east Research Station, St. Joseph, Louisiana, 1931-80. Louisiana Agric. Expt.Bull. No.755.

WILLIAMS, M.R. 1994. Cotton insect losses estimates, 1993. Proc. Beltwide CottonConference, National Cotton Council, Memphis, TN.

WILSON, J. W. 1932. Note on the biology of Laphygma exigua (Huebner). Florida En-tomol. 16:33-39.

460



KEYS TO SOLDIER AND WINGED ADULT TERMITES (ISOPTERA) OF FLORIDA

R

UDOLF

H. S

CHEFFRAHN

AND

N

AN-

Y

AO

S

U

Ft. Lauderdale Research and Education CenterUniversity of Florida, Institute of Food & Agric. Sciences

3205 College Avenue, Ft. Lauderdale, FL 33314

A

BSTRACT

Illustrated identification keys are presented for soldiers and winged adults of thefollowing 17 termite species known from Florida:

Calcaritermes nearcticus

Snyder,

Neotermes castaneus

(Burmeister),

N. jouteli

(Banks),

N. luykxi

Nickle and Collins,

Kalotermes approximatus

Snyder,

Incisitermes milleri

(Emerson),

I. minor

(Hagen),

I.schwarzi

(Banks),

I. snyderi

(Light),

Cryptotermes brevis

(Walker), and

C. cavifrons

Banks, Family Kalotermitidae;

Coptotermes formosanus

Shiraki,

Reticulitermes fla-vipes

(Kollar),

R. hageni

Banks,

R. virginicus

(Banks), and

Prorhinotermes simplex

(Hagen), Family Rhinotermitidae; and

Amitermes floridensis

Scheffrahn, Mangold, &Su, Family Termitidae.

Key Words: Identification, Kalotermitidae, Rhinotermitidae, Termitidae

RESUMEN

Se presentan claves ilustradas de identificacion para los soldados y los adultos conalas de las 17 especies de termes conocidas de la Florida, U.S.A.:

Calcaritermes nearc-ticus

(Snyder),

Neotermes castaneus

(Burmeister),

N. jouteli

(Banks),

N. luykxi

Nickley Collins,

Kalotermes approximatus

Snyder,

Incisitermes milleri

(Emerson),

I. minor

(Hagen),

I. schwarzi

(Banks),

I. snyderi

(Light),

Cryptotermes brevis

(Walker), y

C. ca-vifrons

Banks, Familia Kalotermitidae;

Coptotermes formosanus

Shiraki,

Reticuliter-mes flavipes

(Kollar),

R. hageni

Banks,

R. virginicus

(Banks), y

Prorhinotermessimplex

(Hagen), Familia Rhinotermitidae; y


Scheffrahn, Man-

gold, y Su, Familia Termitidae.

A number of identification keys have been published for the termites of the UnitedStates (Banks & Snyder 1920; Light 1934a,b; Snyder 1954; Weesner 1965), includingfour for the termites of Florida and the southeastern states (Emerson & Miller 1943,Miller 1949, Weesner 1965, Gleason & Koehler 1980). Additionally, Nickle & Collins(1989) have published a key to drywood termites (Kalotermitidae) of the eastern U.S.,all of which occur in Florida. In fact, the only eastern Nearctic termite species notfound in Florida are

Reticulitermes arenincola

Goellner known from Indiana and theBoston, Massachusetts, area (Dobson 1918, Snyder 1949) and

R. tibialis

Banks whichextends its eastern range into Illinois and Indiana (Snyder 1954).

Unclear or sparse illustrations, illustrations not drawn to scale or lacking a scale,heavy reliance on morphometrics, use of obsolete names, and typographical errorshave, in some earlier termite keys, led to confusion and incorrect identifications, es-pecially by nonspecialists. The recent addition of three species to Florida’s termitefauna,

Incisitermes minor

(Hagen) (Scheffrahn et al. 1988),


Scheffrahn et al. (1989), and

Neotermes luykxi

Nickle & Collins (1989), has furtherrendered previous keys obsolete.



, Vol. 77, No. 4 (1994).

FEO




This document was created with FrameMaker 4.0.2

Scheffrahn and Su: Florida Termite Keys

461

The condition of a specimen will greatly affect the probability of a correct identifi-cation. Desiccated specimens are the most difficult to identify because of the resultantshrinkage, color change (usually darkening), and fragile nature resulting in lost orbroken appendages. Usually only the wings and mandibles of dry specimens tend toremain relatively unaltered. Termites are best kept alive after collection and thenkilled by freezing just before being keyed. If specimens cannot be kept alive, theyshould be immersed in aqueous ethanol or isopropanol of at least 40% (i.e., 80-proofliquor or rubbing alcohol). For long-term museum storage, 85% ethanol has proven tobe the best preservative (M.S. Collins, pers. comm.). The mandibles of dead soldiersare usually crossed and the labrum may be retracted or folded. Alate wings, especiallyin the critical costal region, may curl ventrally. Wings alone are often collected follow-ing a dispersal flight and can yield at least a generic identification using the adult key.Wings must be completely flat in order to see the costal venation in proper perspec-tive. This can be accomplished by immersing the wing in a reservoir of water or alco-hol, sliding it onto a microscope slide or other clear flat surface, covering it withanother slide, and allowing it to dry. Alternatively, a dried wing can be flattened bylaying the dorsal surface on a drop of water. Wing membrane texture can best be ob-served when dry. Because the winged adult key uses the forewing, several wingsshould be examined and keyed if detached from the body. Alates collected before dis-persal flights may be incompletely sclerotized causing cuticle, wing membrane, andveins to be lighter in color than when fully mature for flight.

From a practical standpoint, correct identification is especially critical for pesttaxa, such as termites, which may require very different control methods dependingupon the target species. Although the morphological diversity among the termites ofFlorida is moderately broad, some species are not easily distinguished. Fortunately,the tentative identification of the soldier caste can be confirmed or refuted by inde-pendent identification of the winged adult (alate), and vice versa. Alates, however, areseasonal, may be difficult to find, and occur only in a mature colony.

In the following keys, we attempt to separate species by parsimonious use of themost recognizable and consistent characters even if resultant groupings are not tax-onomically related (e.g., grouping by presence or absence of wing membrane pigmen-tation). Simple measurements are used to supplement couplets or when dimensionprovides a clear separation of a group or species. This reduces the confusion resultingfrom the presence of long- and short-headed soldier forms in some kalotermitid spe-cies (Nickle & Collins 1989) or size variations among conspecific soldiers due to colonysize, age, or nutritional status. Adult measurements are less variable than those ofsoldiers. To further help in identification, we have incorporated the known Floridadistribution, pest status, and dispersal flight data based on a previous survey (Schef-frahn et al. 1988) and unpublished records. These are given only as general guidelinesand exceptions may occur (i.e. autumn flights by

Incisitermes snyderi

(Light) and

Reti-culitermes

spp.). When available, generally accepted common names (Snyder 1954,R.H.S. unpublished) or accepted common names (ESA 1989) are also provided.

Several taxonomic issues must be addressed with respect to this work. The firstand most troublesome, is the character overlap between

Neotermes jouteli

(Banks)and

Neotermes luykxi

. All measurements and characters provided in the descriptionof

N. luykxi

soldiers and adults (Nickle & Collins 1989) fall within the range of thosedesignated as

N. jouteli

in our reference collection. Apparently, the only diagnosticcharacters separating the two are their respective chromosome numbers and alloz-yme patterns (Luykx et al. 1990) neither of which can be obtained from preservedspecimens. Chromosome number has been shown to vary within single insect species(Emmel et al. 1973) although it appears to be stable within species of Kalotermitidae

462



(Luykx 1990). Therefore, we cannot differentiate between these two

Neotermes

spe-cies in either key. Secondly,

Prorhinotermes simplex

(Hagen), the Florida “dampwood”termite, shares its habit of nesting in moist, decaying wood with the true dampwoodtermites (

Neotermes

spp.), although the former is actually a subterranean termite(Family Rhinotermitidae) which we have observed tunneling in soil. Thirdly, separat-ing soldiers of

Reticulitermes

species is difficult. Although head and pronotum mea-surements and mandibular characters are useful, precise micromeasurements arerequired and some interspecific overlap may occasionally surface. In subsequentstudys (Hostettler et al. 1995), labrum shape, although also subtle, has been found tobe an effective additional character for separating soldiers of all three

Reticulitermes

species. Finally, an ongoing revision of Nearctic

Reticulitermes

suggests that an un-described or erroneously synonymized species may occur in Florida’s panhandle (T.Myles pers. comm.).

M

ATERIALS

AND

M

ETHODS

Line drawings of specimens were prepared at 20-80x magnification with the aid ofa camera lucida attached to an Olympus SZH light microscope. Measurements weremade with an ocular micrometer. Scanning electron micrographs were made with aHitachi S-4000 field emission microscope (6-8 kV). Specimens were dehydrated in ab-solute ethanol and 1,1,1,3,3,3- hexamethyldisilazane (Nation 1983) prior to sputtercoating with gold.

Material examined for this key is from the authors’ reference collection containingabout 1,200 colony samples taken in Florida between 1985 and 1994 including 785samples collected from structures in peninsular Florida (Scheffrahn et al. 1988), theFlorida State Collection of Arthropods (Fla. Dept. Agric. Cons. Serv., Division of PlantIndustry, Gainesville, Florida) and the E.M. Miller collection from the University ofMiami on loan from P. Luykx containing 111 samples taken in Florida between 1930and 1968.

K

EY

T

O

T

ERMITE

S

OLDIERS

O

F

F

LORIDA

1 Pronotum (Fig. 8a) as wide or wider than width of head viewed fromabove (Figs. 1-20 dorsal views); for species with prominent mandibles,inner margin of left mandible (Fig. 8e) with two or more marginal teeth(Figs. 8-20 dorsal views). (

Drywood and dampwood termites)

FamilyKalotermitidae .......................................................................................... 2

- Pronotum width narrower than width of head viewed from above; eachmandible with no exposed teeth or only one tooth visible on inner margin(Figs. 22-32 dorsal views). (

Subterranean termites)

Families Rhinoter-mitidae and Termitidae ...........................................................................11

2 Frons nearly vertical with deep furrow or rimmed above by a ridge; headplug-like; mandibles not prominent; head color deep reddish brown toblack; (Figs. 1,2,4-7). (

Powderpost drywood termites)

............................. 3 - Frons (Fig. 8c) slopes more or less gradually from plane of vertex (Fig.

8b), surface smooth; head flattened, quadrate or elongate; mandiblesproject prominently; head color orange to reddish brown; (Figs. 8-21).(

Drywood and dampwood termites

) ......................................................... 5 3 Frons with deep furrow (Figs. 1,2); foretibia with one prominent spur at

right angle to tibial axis and two small apical spurs (Fig. 3). (

Rare instructures, known from Clay Co. to Sebring.

) ...........................................

........................................................................... Calcaritermes nearcticus

a

Scheffrahn and Su: Florida Termite Keys

463

Figs. 1-9. Dorsal and lateral views of heads and pronota of termite soldiers fromFlorida: Calcaritermes nearcticus, Figs. 1- 2 (foreleg, Fig. 3; bar = 3.2 mm); Cryptoter-mes cavifrons, Figs. 4-5; Cryptotermes brevis, Figs. 6-7; Neotermes jouteli, Figs. 8-9(pronotum 8a, vertex 8b, frons 8c, antenna 8d, mandible 8e, labrum 8f, eyespot Fig.9a). Bar = 2 mm.

464



- Ridge surrounding frons forming “bowl” (Figs. 5,7); foretibia lacking aprominent apical spur............................................................................... 4

4 Vertex smooth (Figs. 4,5); smaller species. (

Uncommon structural pest(moderate moisture requirement), known from St. Johns Co. south

) .......

.............................................................................. Cryptotermes cavifrons

a

- Vertex rough, wrinkled, often concave (Figs. 6,7); larger species. (

Intro-duced species; common pest of structures and furniture statewide; neverfound in non-structural wood - West Indian powderpost termite.

) ...........

.....................................................................................Cryptotermes brevis

5 Eyespot (Fig. 9a) black; antennae with up to 19 segments; third anten-nal segment about as long as fourth and fifth combined; soldiers usuallylarge (Figs. 8,9). (

Occasional pest in moisture-exposed wood, known fromFt. Pierce south

)

............................................................ Neotermes jouteli

a,b

- Eyespot hyaline or indistinct; number and size of antennal segmentsvariable, soldier size variable................................................................... 6

6 Third antennal segment greatly enlarged and club-like, as long or longerthan fourth through sixth combined, and about twice as wide as fourth(Figs. 10,11,S1); larger species. (

Regularly introduced into Florida as astructural pest, may be permanently established in some areas - westerndrywood termite

) .......................................................... Incisitermes minor - Third antennal segment shorter than fourth through sixth combined

and less than twice as wide as fourth...................................................... 7 7 Anterior margin of pronotum weakly and evenly concave; length of third

antennal segment less than fourth and fifth combined (Figs. 12-15) .... 8 - Anterior margin of pronotum incised (Figs. 16,18,20); length of third an-

tennal segment about equal to or greater than fourth and fifth combined(Figs. S3,S5) .............................................................................................. 9

8 Pronotum more than twice as wide as long, collar-like, posterior marginwith rounded corners; third antennal segment equal to or slightly longerthan second or fourth; lateral margins of mandibles widen near basesbut do not constitute “humps”; large species (Figs. 12,13). (Occasionalpest in moisture-exposed wood and living trees, known from Lake Co.south.) .......................................................................Neotermes castaneusa

- Pronotum more square, less than twice as wide as long, posterior marginnearly straight with square corners; third antennal segment longer thansecond but shorter than fourth and fifth combined; lateral margins ofmandibles with distinct “humps” near bases; medium-small species(Figs. 14,15). (Uncommon structural pest, known from Sarasota north.)...........................................................................Kalotermes approximatus

9 Small species; antennae with 10-11 segments; pronotum about 1 mmwide, posterior margin rather evenly convex (Figs. 16,17). (Known onlyfrom Florida Keys, pest status unknown) ................. Incisitermes milleria

- Medium species; antennae with 11-16 segments; pronotum 1.3-1.9 mmwide, posterior margin more straight or slightly concave in middle, cor-ners rounded (Figs. 18,20) ...................................................................... 10

10 Tip of labrum bluntly pointed (Fig. S2); third antennal segment as longas fourth and fifth combined (Fig. S3); antennae with 11-14 segments(Figs. 18,19). (Common in structural wood statewide - southeastern dry-wood termite) .............................................................. Incisitermes snyderi

- Tip of labrum truncate (Fig. S4); third antennal segment longer thanfourth and fifth combined (Fig. S5); antennae with up to 16 segments(Figs. 20,21). (Rare structural pest, known mostly from coastal south) .. .

Scheffrahn and Su: Florida Termite Keys 465

................................................................................. Incisitermes schwarzia

11 Teeth on inner margin of mandibles reduced to serrations at base and sousually hidden from view by labrum; head capsule not elliptical whenviewed laterally (Figs. 24-33). Family Rhinotermitidae .......................12

Figs. 10-17. Dorsal and lateral views of heads and pronota of termite soldiers fromFlorida: Incisitermes minor, Figs. 10-11; Neotermes castaneus, Figs. 12-13; Kalotermesapproximatus, Figs. 14-15; Incisitermes milleri, Figs. 16-17. Bar = 2 mm.


Figs. S1-S7. Scanning electron micrographs of Incisitermes minor soldier antenna,Fig. S1; I. snyderi soldier labrum, Fig. S2, and antenna, Fig. S3; I. schwarzi soldier la-brum, Fig. S4 (mandible tips broken), and antenna, Fig. S5; Reticulitermes virginicussoldier mandibles, Fig. S6; R. hageni soldier mandibles, Fig. S7.


- One prominent triangular tooth on inner margin of each sickle-shapedmandible, head capsule elliptical when viewed laterally (Figs. 22,23);smallest soldier caste in Florida. Family Termitidae. (Occasionally asso-ciated with structural lumber, known from west central Florida - Floridadark-winged subterranean termite) .......................Amitermes floridensisa

12 Head outline rectangular from above, sides of head parallel (Figs.24,26,28). (Reticulitermes spp)................................................................13

- Head outline oval or egg-shaped from above, narrowing in front, sides ofhead convex (Figs. 30,32) ........................................................................15

13 Pronotum width usually greater than 0.90 mm; head length with man-dibles equal to or greater than 2.8 mm; points of mandibles, especiallyleft, curved inward about 70-90° (Figs. 24,25). (Widespread pest through-out state - eastern subterranean termite.).............Reticulitermes flavipesc

- Pronotum width usually less than 0.85 mm; head length with mandiblesless than or equal to 2.7 mm; curvature of mandible points 45-90° .....14

14 Larger species (Figs. 26,27), pronotum width greater than 0.70 mm;points of mandibles, especially left, curved inward about 70-90°, pointsof mandibles broader (Fig. S6) than following species; basal serrations ofleft mandible, when exposed for viewing, more prominent (Fig. S6); dis-tinct and gradual inward curvature of blade of right mandible (Fig. S6).(Widespread pest throughout state - dark southern subterranean ter-mite) ...................................................................Reticulitermes virginicusc

- Smaller species (Figs. 28,29), pronotum width less than or equal to 0.70mm; points of mandibles, especially left, curved inward about 45°, pointsmore slender (Fig. S7) than above species; basal serrations of left man-dible, when exposed for viewing, less prominent (Fig. S7); blade of rightmandible more straight before point (Fig. S7). (Less common in struc-tures statewide - light southern subterranean termite)............................................................................................................... Reticulitermes hagenic

15 Fontanelle consisting of a prominent, oval, anterior-facing opening aris-ing from a mound on vertex and frons (Figs. 30,31a). (Introduced speciescommon in or near structures in certain areas of Broward, Dade, Hills-borough, and Orange Cos., and coastal panhandle - Formosan subterra-nean termite.) ...................................................... Coptotermes formosanus

- Fontanelle consisting of a minute, circular, dorsal-facing opening on sur-face of vertex (Figs. 32a, 33). (Occasionally in structures in Broward andDade Cos. - Florida “dampwood” termite)................................................................................................................................Prorhinotermes simplexa

KEY TO WINGED ADULT TERMITES OF FLORIDA

1 With wing unfolded and flattened between glass plates, three or moresclerotized veins in costal field (costal margin, subcosta, radius, radialsector, and, in some, median, e.g., Fig. 37a,c-e and Fig. 45a-c) at aboutone-third wing length from wing suture; in most species, numerous di-agonal cross veins connecting two or more remaining veins in costal fieldalong remaining length of wing (Figs. 34,35-37, 39,41-45). (Drywood andtrue dampwood termites)...........................................................................2

- Two sclerotized veins in costal field (costal margin and radial sector, e.g.,Fig. 46a-b) in foremargin of wings visible along entire length of wing


and, in most species, connected by short vertical cross veins in distalthird of wing (Figs. 46-48,50,52,54). (Subterranean termites).............. 10

2 When viewed over white background or with several wings overlappingas when folded over the abdomen, entire wing membrane translucentlypigmented blackish; veins in costal field darker than membrane ......... 3

Figs 18-33. Dorsal and lateral views of heads and pronota of termite soldiers fromFlorida: Incisitermes snyderi, Figs. 18- 19; I. schwarzi, Figs. 20-21; Amitermesfloridensis, Figs. 22-23; Reticulitermes flavipes, Figs. 24-25; R. virginicus, Figs. 26-27;R. hageni, Figs. 28-29; Coptotermes formosanus, Figs. 30-31 (fontanelle 31a); Prorhi-notermes simplex, Figs. 32-33 (fontanelle 32a). Bar = 2 mm.


- Wing membrane unpigmented or very faintly yellow-brown, veins in cos-tal field white to medium brown when viewed as above.........................5

3 In forewing, median vein is sclerotized and runs near veins in costal field(Fig. 34a), no diagonal cross veins connecting veins in costal field; wingmembrane with distinct papillae or bumps; length with wings 7 mm.(Rare in structures, known from Clay Co. to Sebring, midday flightsMarch to May.)...................................................Calcaritermes nearcticusa

- In forewing, median vein is unsclerotized and runs midway betweenveins in costal field above, and cubitus below; diagonal cross veins be-tween sclerotized veins in costal field (Figs. 35,36).................................4

4 Head and pronotum orange-brown, abdomen dark brown; stout-bodied,medium-large species, length with wings 11-12.5 mm; hairs on headshorter than diameter of eye; arolium absent between tarsal claws; inforewing, few diagonal cross veins branching forward from radial sector(Fig. 35). (Regularly introduced into Florida as a structural pest, may bepermanently established in some areas, midday flights September to No-vember - western drywood termite.) ............................Incisitermes minor

- Head, thorax, and abdominal tergites (plates) reddish brown;medium-small species, length with wings 8.5-10 mm; hairs on headlonger than diameter of eye; arolium present between tarsal claws; inforewing, few cross veins branching forward from median vein (Fig.36a). (Uncommon in structures, from Sarasota north, daytime flightsSeptember to November)................................... Kalotermes approximatus

5 In forewing, four sclerotized veins in costal field (costal margin, radius,radial sector, and median, e.g., Fig. 37a, c-e, respectively) at aboutone-third wing length from body; sclerotized media running close to ra-dial sector (Figs. 37,39); large, stout-bodied species. ................................(Dampwood termites) ................................................................................6

- In forewing, three sclerotized veins in costal field (costal margin, radius,and radial sector, e.g., Fig. 45a-c, respectively) at about one-third winglength from body, media (Fig. 45d) not sclerotized and running midwaybetween radial sector and cubitus (Figs. 41-45); size variable. ................(Powderpost and drywood termites) .........................................................7

6 Head, body, and veins in costal field chestnut brown; long erect hairs onhead and pronotum (Fig. 38); largest alate caste in Florida, length withwings about 15-16 mm (forewing, Fig. 37). (Occasional pest inmoisture-exposed wood and living trees, known from Lake Co. south,evening flights peak in October and November.) ..........................................................................................................................Neotermes castaneusa

- Head, body, and veins in costal field light yellowish-brown toreddish-brown; very short hairs on pronotum (Fig. 40); wing membranevery faintly yellow-brown; length with wings 12-15 mm (forewing, Fig.39). (Occasional pest in moisture-exposed wood, known from Vero Beachsouth, evening flights Spring or Fall.) .........................Neotermes joutelia,b

7 In forewing, unsclerotized media curving near mid-wing to join veins incostal field (Figs. 41a,42a; note variations in C. brevis forewing veinationin Scheffrahn et al. (1988, Fig. 2.); head and body brown.......................8

- In forewing, unsclerotized media running to near tip of wing even ifbranched along its course (Figs. 43a,44a,45d).........................................9

8 Small dull-brown species, length with wings 8-9 mm, wing membraneweakly tuberculate (pimply); head width (through eyes) 0.85-0.97 mm;


Figs. 34-44. Right forewing of termite adults from Florida: Calcaritermes nearcti-cus, Fig. 34 (median vein 34a); Incisitermes minor, Fig. 35 (median vein 35a); Kaloter-mes approximatus, Fig. 36 (median vein 36a); Neotermes castaneus, Fig. 37 (costalmargin 37a, subcostal vein 37b, radius 37c, radial sector 37d, and media 37e); anddorsal view of pronotum, Fig. 38; N. jouteli, Fig. 39, and dorsal view of pronotum, Fig.40; Cryptotermes cavifrons, Fig. 41 (median vein 41a); C. brevis, Fig. 42 (median vein42a); Incisitermes milleri, Fig. 43 (median vein 43a); I. snyderi, Fig. 44 (median vein44a). Bar = 4 mm for forewings, 2.4 mm for pronota.


antennae with 13-16 segments (forewing, Fig. 41). (Uncommonstructural pest (moderate moisture requirement), known from St. JohnsCo. south, evening flights year-round.) ...............Cryptotermes cavifronsa

- Medium dull-brown species, length with wings 10-11 mm; head width1.05-1.15 mm; antennae with 14-18 segments (forewing, Fig. 42).(Introduced species, common pest of structures and furniture statewide,never found in non-structural wood, evening and night flights April toJuly - West Indian powderpost termite)..................... Cryptotermes brevis

9 Head, thorax, and body dark brown; veins in costal field brown, wingmembrane tuberculate; head width (through eyes) about 0.9 mm; ocellusmore elliptical; small species, length with wings 7-8 mm; (forewing, Fig.43). (Known only from Florida Keys, pest status unknown, daytimeflights April to July) ...................................................Incisitermes milleria

- Head and body color pale yellow-brown to pale reddish brown; veins incostal field pale yellow-brown in distal half of wing; head width 1.20-1.35mm; ocellus more round; medium species, length with wings 11-12 mm(forewing, Fig. 44). (Common in structures statewide, evening flightsMay to August - southeastern drywood termite.) ...........................................................................................................................Incisitermes snyderi

- Head and body color medium brown; veins in costal field brown along en-tire length of wing; head width 1.40-1.52 mm; ocellus more elliptical;medium-large species, length with wings 13-15 mm (forewing, Fig. 45).(Rare structural pest, known mostly from coastal south, small evening ornight flights except during winter, peaking in April and May) .................................................................................................. Incisitermes schwarzia

10 Wing membrane smooth between veins; wing surface and marginadorned with fine hairs (Figs. 46,47) ..................................................... 11

- Wing membrane net-like (reticulate) between veins, no hairs on wingsurface or margin (Figs. 48,50,52,54).....................................................12

11 Head and pronotum yellow-brown; wing membrane unpigmented; veinsin costal field (Fig. 46a,b) yellowish brown at base to almost white at tip;large species, length with wings about 14 mm (forewing, Fig. 46). (Intro-duced species common in or near structures in certain areas of Broward,Dade, Hillsborough, and Orange Cos., and coastal panhandle, late after-noon and evening flights April to July- Formosan subterranean termite)............................................................................. Coptotermes formosanus

- Head and pronotum dark brown; wing membrane dark with blackinterior veins (Fig. 47); small species with wings long in proportion tobody length; length with wings about 9 mm. (Occasional structural andoutdoor nuisance (large swarms), known from west central Florida,daytime flights following rain June to September - Florida dark-wingedsubterranean termite (Family Termitidae)).................................................................................................................................Amitermes floridensisa

12 Body color pale brown to light reddish brown .......................................13 - Body color dark brown to black ..............................................................14 13 Forewing not broad in middle, costal margin not convex, median vein

runs uninterrupted below veins in costal field (Fig. 48a); thorax and ab-domen narrow (Fig. 49); small species, length with wings 7-8 mm. (Lesscommon in structures statewide, midday flights in sunshine December toApril - light southern subterranean termite.) ...............................................................................................................................Reticulitermes hageni


- Forewing broad in middle, costal margin covex, median vein disjointed,indistinct (Fig. 50a); thorax and abdomen broader than above (Fig. 51);medium-small species, length with wings 9-10 mm. (Occasionally instructures in Broward and Dade Cos., evening and night flights Octoberto January - Florida “dampwood” termite.) ........................................................................................................................... Prorhinotermes simplexa

Figs. 45-55. Right forewing of termite adults from Florida: I. schwarzi, Fig. 45 (cos-tal margin 45a, radius 45b, radial sector 45c, and media 45d); Coptotermes formosa-nus, Fig. 46 (costal margin 46a and radial sector 46b); Amitermes floridensis, Fig. 47;Reticulitermes hageni, Fig. 48 (median vein 48a), and dorsal view of body, Fig. 49; Pro-rhinotermes simplex, Fig. 50 (median vein 50a), and dorsal view of body, Fig. 51; R. fla-vipes, Fig. 52, lateral view of head, Fig. 53; R. virginicus, Fig. 54, lateral view of head,Fig. 55. Bar = 4 mm for forewings, 2.4 mm for heads and bodies.


14 Medium-small species, length with wings 8.5-10.5 mm; ocellus about onetime its diameter or more from compound eye (Fig. 53); veins in costalfield of wing light brown, membrane faintly yellow-brown (forewing, Fig.52). (Widespread pest throughout state, midday flights in sunshineJanuary to April - eastern subterranean termite) .......................................................................................................................Reticulitermes flavipes

- Small species, length with wings 7.0-9.5 mm, usually 7.0-8.0 mm; ocellusless than its diameter from compound eye (Fig. 55); veins in costal fieldof wing whitish or hyaline except near base, membrane hyaline (forew-ing, Fig. 54). (Widespread pest throughout state, midday flights in sun-shine March to May - dark southern subterranean termite.) ................................................................................................Reticulitermes virginicus

FOOTNOTES FOR KEYS

a In the United States, known only from Florida.b Indistinguishable from Neotermes luykxi. See introduction.c For additional characters see Hostettler et al. (1995).

ACKNOWLEDGMENTS

We thank D.S. Williams of the ICBR Electron Microscope Core Facility at the Uni-versity of Florida, Gainesville, for technical assistance with electron microscopy; andM. S. Collins, F. W. Howard, S. Jones, J. Krecek, P. Luykx, T. Myles, J. Peters, and J.Tsai for reviewing and improving various stages of this contribution no. R-03258 ofthe Florida Agricultural Experiment Stations Journal Series.

REFERENCES CITED

BANKS, N. AND T.E. SNYDER. 1920. A revision of the Nearctic termites with notes onbiology and geographic distribution. U.S. Natl. Mus. Bull. 108, 228 pp.

DOBSON, R.J. 1918. A European termite Reticulotermes [sic!] lucifugus Rossi in the vi-cinity of Boston. Psyche 25: 99- 101.

EMERSON, A.E., AND E.M. MILLER. 1943. A key to the termites of Florida Entomol.News 54: 184-187.

EMMEL, T.C., H.R. TREW, AND O. SHIELDS. 1973. Chromosomal variability in a Nearc-tic lycaenid butterfly, Philotes sonorensis (Lepidoptera: Lycaenidae).Pan-Pacific Entomol. 49: 74-80.

ENTOMOLOGICAL SOCIETY OF AMERICA. 1989. Common names of insects and relatedorganisms. Lanham, MD. 199 pp.

GLEASON, R.W., AND P.G. KOEHLER. 1980. Termites of the eastern and southeasternUnited States: pictorial keys to soldiers and winged reproductives. Flor. Coop.Ext. Serv., Inst. Food Agric Sci., Univ. Florida Bull. 192.

HOSTETTLER, N.C., D.W. HALL, AND R.H. SCHEFFRAHN. 1995. Morphometric variationand labral shape in Florida Reticulitermes (Isoptera: Rhinotermitidae): signif-icance for identification. Florida Entomol. (in press).

LIGHT, S.F. 1934a. The desert termites of the Genus Amitermes, pp. 199-205 in C. A.Kofoid [ed.]. Termites and termite control. University of California Press, Ber-keley, Calif. 795 pp.

LIGHT, S.F. 1934b. Dry-wood termites, their classification and distribution, ibid. pp.206-209.

LUYKX, P. 1990. A cytogenetic survey of 25 species of lower termites from Australia.Genome 33: 80-88.


LUYKX, P., D.A. NICKLE, AND B.I. CROTHER. 1990. A morphological, allozymic, andkaryotypic assessment of the phylogeny of some lower termites (Isoptera: Kal-otermitidae). Proc. Entomol. Soc. Washington 92: 385-399.

MILLER, E.M. 1949. A handbook on Florida termites. Tech. Ser., Univ. Miami Press,Coral Gables, FL, 30 pp.

NATION, J.A. 1983. A new method using hexamethyldisilazane for the preparation ofsoft insect tissue for scanning electron microscopy. Stain Technol. 55: 347-352.

NICKLE, D.A., AND M.S. COLLINS. 1989. Key to the Kalotermitidae of eastern UnitedStates with a new Neotermes from Florida (Isoptera). Proc. Entomol. Soc.Washington 91: 269-285.

SCHEFFRAHN, R.H., J.R. MANGOLD, AND N.-Y. SU. 1988. A survey ofstructure-infesting termites of peninsular Florida. Florida Entomol. 71:615-630.

SCHEFFRAHN, R.H., N.-Y. SU, AND J.R. MANGOLD. 1989. Amitermes floridensis, a newspecies and first record of a higher termite in the eastern United States(Isoptera: Termitidae: Termitinae). Florida Entomol. 72: 618-625.

SNYDER, T.E. 1949. Catalog of the termites (Isoptera) of the world. Smithsonian Misc.Coll. No. 3953, 112: 1-490.

SNYDER, T.E. 1954. Order Isoptera. The termites of the United States and Canada.Natl. Pest Contr. Assn., New York, NY, 64 pp.

WEESNER, F.M. 1965. Termites of the United States, A handbook. Natl. Pest Contr.Assn., Elizabeth, New Jersey, 70 pp.

♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦

474



ODONTOTAENIUS FLORIDANUS

NEW SPECIES (COLEOPTERA: PASSALIDAE): A SECOND U.S. PASSALID

BEETLE

J

ACK

C. S

CHUSTER

Systematic Entomology LaboratoryUniversidad del Valle de Guatemala

Aptdo. 82Guatemala City, GUATEMALA

A

BSTRACT

Larvae and adults of

Odontotaenius floridanus

New Species

are described fromthe southern end of the Lake Wales Ridge in Highland Co., FL. This species may haveevolved as a population isolated during times of higher sea level from the mainlandspecies

O. disjunctus

(Illiger) or a close common ancestor. It differs notably from

O.disjunctus

in having much wider front tibiae and a less pedunculate horn. A key isgiven to the species of the genus.

Key Words: Florida, endemism, Lake Wales

R

ESUMEN

Son descritas las larvas y adultos de


Nueva Especie

del extremo sur de Lake Wales Ridge, en Highland Co., Florida. Esta especie pudo ha-ber evolucionado, como una población aislada en épocas en que el nivel del mar era



, Vol. 77, No. 4 (1994).

FEO




Schuster:


, A New U.S. Passalid

475

más alto, a partir de

O. disjunctus

(Illiger) o de otro ancestro común cercano. Difierenotablemente de

O. disjunctus

en tener las tibias delanteras más anchas y el cuerno

menos pedunculado. Se ofrece una clave para las especies del género.

Only one species of Passalidae,

Odontotaenius disjunctus

(Illiger), is known to oc-cur in the U.S. at present, though two other species may have occurred in Arizona atthe turn of the century (Schuster 1983).

Recently, while examining

O. disjunctus

in the Florida State Collection of Arthro-pods in Gainesville, I noted two specimens with a somewhat different morphology. Onexamining the labels, I noticed that the collector, L. L. Lampert, had also remarked ontheir uniqueness. Both came from the same area of south-central Florida in High-lands Co. Later, I had an opportunity to examine the collection of the Archbold Bio-logical Station and encountered three more similar specimens. Subsequently, withthe aid of four other Florida entomologists, I conducted a search for this elusive insectat the Archbold site. One of the collaborators, Paul Skelley, managed to find an oak logwith a pair of adults and four larvae. All seven adult specimens fit the description be-low.

The genus

Odontotaenius

was revalidated by Reyes-Castillo (1970) and includeseight species (Reyes-Castillo 1970, Castillo et al. 1988). Three of these species, knownonly from the types, are probably synonyms of either

O. striatopunctatus

(Percheron)or

O. zodiacus

(Truqui). The types need to be examined to make further synonymies.

Odontotaenius

is characterized by a marked fronto-clypeal suture, thick anteriorclypeal border, median frontal structure of “striatopunctatus” type, posterior half ofsupraorbital ridges bifurcate, and short antennal lamellae with the distal marginsrounded (Reyes-Castillo 1970).


Schuster

New Species

DESCRIPTION. Head: Anterior border of labrum deeply concave. Clypeus greatlyswollen in middle. Median frontal structure (“horn”) of “striatopunctatus” type(Reyes-Castillo 1970) (Fig. 1). Supraorbital ridge bifurcated posteriorly. Canthus ex-tends laterally same distance as eye margin, anterior corner with right angle. Eyessmall, ratio of dorsal eye width to head width 1:11.4. Lateral circular scars of mentumindistinct or absent.

Thorax: Lateral fossa of pronotum with 1-4 light punctations. Mesosternum bare,without lateral depressions, with wide (0.7 mm) matt bands along anterior borders.Mesepisternum pubescent. Metasternum with 10-18 punctations delimiting each lat-ero-posterior side of disk, anterior angles pubescent, lateral fossae narrow and pubes-cent.

Elytra: Anterior profile convex, anterior face of elytra sloping. Striae 7 and 8united anteriorly.

Wing: Normal size, not reduced.Legs: Tibia I very wide (Fig. 2), tibia ratio (see Fig. 3) 0.264-0.333, x = 0.312, n = 7.Dimensions (mm): Total length, mandible tip to elytral tip 36-42, x = 40.2; elytral

length 18.5-21, x = 20.2, elytral width 12-15, x = 13.6, pronotal width 11.5-14.5, x =13.5.

LARVA. The larva has only 12-14 AR setae and 7-8 internal coxal setae. Other-wise, the basic setal pattern is the same as in

O. disjunctus

. Larval head widths: in-star III = 6.0, instar II = 4.1-4.3.

476



DIAGNOSIS. The adult is most similar to

O. disjunctus

. The latter species differsfrom

O. floridanus

in having a rounded canthus which projects beyond the eye mar-gin, larger eyes (dorsal eye width to head width ratio 1:9.5 - 1:10), mentum with dis-

Fig. 1. Lateral view of heads of O. disjunctus (left) and O. floridanus (right) show-ing “horn” (median frontal structure) shapes.

Fig. 2. Dorsal view of front tibiae of O. disjunctus (left) and O. floridanus (right)showing size difference.

Schuster:



477

tinct lateral circular scars, usually no punctations in lateral prothoracic fossae,mesosternum with narrow (0.3 mm) matt bands along anterior borders, metasternumwithout punctations delimiting latero-posterior sides of disk, flatter anterior profile ofelytra, anterior face of elytra vertical, elytral striae 7 and 8 not united anteriorly, andnarrow tibia I (ratio 0.185-0.239, x = 0.216, n = 8 Florida specimens). The aedeagi ofthe two species are very similar. The “horn” on the head of

O. floridanus

is not as pe-dunculate as in

O. disjunctus

or

O. striatopunctatus

(Fig. 1).The larva is similar to that of

O. disjunctus

(Schuster & Reyes-Castillo 1981). Ithas fewer AR setae and usually more internal coxal setae than larvae of the latter spe-cies.

MATERIAL EXAMINED. Seven adults and four larvae.TYPE MATERIAL. Holotype male,

Florida

, Highlands Co., Archbold BiologicalStation near Lake Placid, 18 I 93, P. Skelley, in a hardwood log. Allotype female, samedata as holotype, together with four larvae.

Paratypes: Four specimens collected at Archbold Biological Station: 28 III 1973,L.L. Lampert, in pitfall trap; VIII 1970, J. Douglas; 20 IX 1992, U.G. Mueller; 23 IV1983, M. Deyrup, ground. Another specimen was collected at Sebring, Highlands Co.,Flamingo Villas Scrub by P. Martin, 11 IX 1987.

Types will be deposited in the Florida State Collection of Arthropods and the col-lection of the Universidad del Valle de Guatemala.

ETYMOLOGY. The trivial name “floridanus” refers to the state where this speciesis apparently endemic.

Fig. 3. Passalid tibia, ventral view, showing parameters of tibia ratio. The ratio isthe width at the widest point divided by the length shown.

478



D

ISCUSSION

This species is obviously derived from

Odontotaenius disjunctus

or a close commonancestor. It differs most notably in the “horn”, or median frontal structure, and the en-larged front tibiae. This latter characteristic is found in passalids which burrow in theground under logs, as in

Taeniocerus

spp. (Kon & Araya 1992, Kon & Johki 1987), inleaf-cutter ant detritus as in

Ptichopus angulatus

(Percheron) or in passalids in otherdetritus-like habitats (Johki & Kon 1987). Almost nothing is known concerning thehabits of

O. floridanus

.

O. floridanus

is known only from the southern terminus of the Lake Wales Ridgeof Highlands Co., Florida. A high concentration of endemic Florida scrub biota is rec-ognized from this area (Deyrup 1989, 1990).

The history of

Odontotaenius

in North America may be proposed as follows: atsome point during the Cenozoic when mesic forest (

Quercus

,

Liquidambar

,

Acer

, etc.),similar to that of the southeastern U.S. at present, extended relatively unbroken asfar as Honduras, the ancestor of the U.S. species migrated into the U.S. from easternMexico. Subsequently, a dry barrier formed in southern Texas and Tamaulipas, iso-lating the U.S. populations. At various times since the Miocene, the ridges of Florida,especially the Lake Wales ridge, may have been isolated from the rest of the mainlandby marine transgressions (Deyrup 1989). The ridges, then islands in the “Florida Ar-chipelago”, may have given rise to various endemic species, including

O. floridanus

;however, if one considers the fact that many endemic species of the Florida ridges ap-pear to be relict species which had wider distributions at one time (Deyrup 1990),

O.floridanus

may have originated elsewhere and migrated into Florida, only now beingrestricted in its range. Of particular interest now is whether

O. floridanus

is re-stricted to the Lake Wales ridge (as are various other taxa (Deyrup 1989)), or whetherit or other endemic passalid species occur on other Florida ridges. Although its wingsappear normal,

O. floridanus

has not been found in other than Highlands Co., despitethe fact that I have examined hundreds of passalid specimens from Florida.

O. dis-junctus

is found throughout much of Florida north of Lake Okeechobee (Schuster1983), including the Archbold Biological Station, where it is sympatric with

O. flori-danus

.Other interesting questions concern the degree of ecological overlap between these

two Florida species. Does habitat sympatry occur, i.e., do they occur in the same foresttypes? I suspect this may be the case, considering that

O. disjunctus

inhabits a widevariety of broadleaf forests in North America, including the relatively dry turkey-oaksandhills of north central Florida (Schuster 1978). Does microhabitat sympatry occur,i.e., do they occur in the same kind (species, degree of decomposition) of logs, or eventhe same log? This would not be surprising, considering that Luederwaldt (1931)found 10 species in a single log in Brazil, and frequently three or four species arefound in the same log in the tropics. Further collecting in Florida should answer someof these questions.

The following key is based on that of Castillo et al. (1988):

K

EY

TO

THE

S

PECIES

OF

O

DONTOTAENIUS

1. Frontal fossae glabrous, clypeus swollen or with triangular projection inmiddle ........................................................................................................ 3

1’ Frontal fossae pubescent, clypeus uniform width throughout or nar-rower in middle ......................................................................................... 2

Schuster:



479

2. Metasternal disc delimited by punctations, eyes reduced;

Mexico

, Si-erra Madre Oriental

.................................................................O. zodiacus

2’ Metasternal disc not delimited by punctations, eyes normal;

Mexico

,Jalisco, Sierra de Manantlán

.................................................... O. cerastes

3. Clypeus with triangular projection in middle, body length <35mm;

Mex-ico

to

Colombia

.........................................................O. striatopunctatus

3’ Clypeus gently swollen in middle.............................................................44. Body length >35mm;

U.S.A., Canada

.....................................................54’ Body length 25-26mm;

Ecuador

..........................................O. striatulus

5. Prothoracic tibiae narrow, horn pedunculate (Figs. 1,2); eastern

U.S.A.

,southeastern

Canada

...........................................................O. disjunctus

5’ Prothoracic tibiae wide, horn extends forward without marked peduncle(Figs. 1,2); south-central

Florida

........................................ O. floridanus

A

CKNOWLEDGMENTS

Special thanks to Michael Thomas and Mark Deyrup for facilitating the expeditionto Highlands Co., Paul Skelley for finding the beasts with larvae in the field, andMark Deyrup and the F.S.C.A. for providing other specimens. Mark Deyrup, PedroReyes-Castillo, Gary Steck and an anonymous reviewer provided cogent criticism ofthe manuscript. The Universidad del Valle de Guatemala provided support.

R

EFERENCES

C

ITED

C

ASTILLO

, C., L.E. R

IVERA

-C

ERVANTES

,

AND

P. R

EYES

-C

ASTILLO

. 1988. Estudio sobrelos Passalidae (Coleoptera: Lamellicornia) de la Sierra de Manantlán, Jalisco.Acta Zool. Mexicana (n.s.) 30: 1-20.

DEYRUP, M. 1989. Arthropods endemic to Florida scrub. Florida Scientist 52(4): 254-270.

DEYRUP, M. 1990. Arthropod footprints in the sands of time. Florida Entomol. 73: 529-538.

JOHKI, Y. AND, M. KON. 1987. Morpho-ecological analysis on the relationship betweenhabitat and body shape in adult passalid beetles (Coleoptera: Passalidae).Mem. Fac. Sci., Kyoto Univ., (Ser. Biol.), 2: 119-128.

KON, M., AND K. ARAYA. 1992. On the microhabitat of the Bornean passalid beetle,Taeniocerus platypus (Coleoptera, Passalidae). Elytra, Tokyo, 20(1): 129-130.

KON, M., AND Y. JOHKI. 1987. A new type of microhabitat, the interface between thelog and the ground, observed in the passalid beetle of Borneo Taeniocerus bi-canthatus (Coleoptera: Passalidae). J. Ethology 5(2): 197-198.

LUEDERWALDT, H. 1931. Monographia dos passalideos do Brasil (Col.). Rev. Mus.Paul., 17 (1st parte).

REYES-CASTILLO, P. 1970. Coleoptera, Passalidae: Morfología y división en grandesgrupos; géneros americanos. Folia Entomol. Mexicana 20-22: 1-240.

SCHUSTER, J. 1978. Biogeographical and ecological limits of New World Passalidae(Coleoptera). Coleopterists Bulletin 32(1): 21-28.

SCHUSTER, J. 1983. The Passalidae of the United States. Coleopterists Bulletin 37(4):302-305.

SCHUSTER, J., AND P. REYES-CASTILLO. 1981. New World genera of Passalidae (Co-leoptera): a revision of larvae. An. Esc. nac. Cienc. Bio., Mexico. 25: 79-116.

480



FEEDING BY

BAGOUS AFFINIS

(COLEOPTERA: CURCULIONIDAE) INHIBITS GERMINATION OF HYDRILLA

TUBERS

K.E. G

ODFREY

AND

L.W.J. A

NDERSON

USDA, ARS, Aquatic Weed Control Research LaboratoryUniversity of California

Davis, CA 95616

A

BSTRACT

Bagous affinis

Hustache (Coleoptera: Curculionidae) larvae feed inside subterra-nean turions or tubers of hydrilla (

Hydrilla verticillata

(L.f.) Royle, Hydrocharita-ceae) during low water conditions. This results in reduced germination of the tubers.To determine the number of

B. affinis

required to reduce tuber germination, dioecioushydrilla tubers were exposed to various

B. affinis

egg to tuber ratios. The tubers werethen held for germination. The number of adults produced and the number of tubersgerminating for each treatment and damage category were recorded. In all treat-ments, tuber germination was significantly reduced compared with the controls. Theproportion of tubers germinating tended to decrease with an increase in the numberof eggs initially placed in the treatment. This reduction in germination resulted froman increase in feeding damage. The results of this study suggest that

B. affinis

shouldbe released in the field with an egg to tuber ratio of 2:1 or greater.

Key Words: Biological control, aquatic weed control, hydrilla tuber weevil, insect feed-ing damage

R

ESUMEN

Las

larvas de

Bagous affinis

Hustache (Coleoptera: Curculionidae) se alimentande los tallos subterráneos (tubérculos) de la elodea de la Florida (


[L.f.] Royle, Hydrocharitaceae) cuando el agua es poco profunda, lo que reduce su ger-minación. Para determinar el número de

B. affinis

requerido para reducir la germi-nación de los tallos subterráneos de la elodea, fueron expuestos tubérculos dióicos avarias densidades de huevos del insecto y se esperó a que germinaran. El número deadultos producido, el número de tubérculos que germinaron y la categoría de los dañosfueron registrados en cada tratamiento. En todas las variantes la germinación de lostubérculos fue significativamente reducida con respecto a los testigos. La proporciónde los tubérculos germinados tendió a disminuir con el aumento del número de huevosinicialmente colocados en cada tratamiento. Esta reducción de la germinación fue elresultado del aumento del daño producido por los insectos al alimentarse de los tallos.Los resultados de este estudio sugieren que

B. affinis

debe liberarse en el campo a una

proporción de huevos por tubérculo de 2:1 o mayor.

Bagous affinis

Hustache (Coleoptera: Curculionidae), the hydrilla tuber weevil, isa biological control agent for hydrilla (


(L.f.) Royle; Hydrocharita-ceae), a submersed aquatic weed. The life cycle of this weevil is geared to a wet-dryseasonal climate. In the dry season, the weevils feed upon the above-ground portionsof the hydrilla plant that are exposed as water recedes from an aquatic site (Balochet al. 1980, Buckingham 1988). Female weevils oviposit in moist organic matter found



, Vol. 77, No. 4 (1994).

FEO




Godfrey & Anderson:

B. affinis

& Hydrilla Tubers

481

in and among the stranded hydrilla plants (Baloch et al. 1980, Buckingham 1988).Upon egg hatch, the larvae burrow through the soil seeking subterranean turions (tu-bers) of hydrilla. The larvae complete three instars while feeding inside the tubersand then pupate either within the tuber or in the soil (Bennett & Buckingham 1991).The feeding activity of the larvae destroys the tubers by consuming the meristems, orby providing an entryway for other organisms such as fungi or bacteria. Destructionof populations of hydrilla tubers, known as tuber banks, is important in controllinghydrilla because the tubers are a source of new infestations for up to 4 years after for-mation of the tubers (Van & Steward 1990, L. W. J. A., unpublished data).

Hydrilla is classified as a Category A pest in California and, as such, must be man-aged with eradication as the objective. In a cooperative program with the CaliforniaDepartment of Food and Agriculture, we investigated the use of the hydrilla tuberweevil in an inundative release program to reduce and possibly eliminate tuber banksat selected sites in California. The hydrilla tuber weevil was selected for use in thisprogram because in its native range it infested almost 100% of hydrilla tubers at a siteduring the dry season. In the following wet season, there was little or no regrowth ofthe hydrilla at this site (Baloch et al. 1980). In California, some of the water systemsinfested with hydrilla undergo a seasonal drawdown, thereby potentially exposing hy-drilla tubers to attack by

B. affinis

. To estimate the number of weevils to be releasedat an infested site, the number of weevils and the amount of feeding damage requiredto cause a reduction in germination of a population of tubers must be determined. Inthis study, the relationship between

B. affinis

density and reduction in tuber germi-nation was investigated by measuring the amount of germination by dioecious hyd-rilla tubers after exposure to different numbers of

B. affinis

larvae. This study wasconducted in the laboratory because the Category A pest designation of hydrilla wouldnot allow the establishment of field plots.

M

ATERIALS

AND

M

ETHODS

The ratio of

B. affinis

to hydrilla tubers required to reduce tuber germination wasinvestigated in experiments that were conducted at the USDA Aquatic Weed ControlResearch Laboratory, Davis, California, from 16 December 1992 to 20 May 1994. Theinsects used in these experiments had been in laboratory culture for 8 to 10 genera-tions. The weevils used to originate this colony were collected outside Bangalore, In-dia in April 1991. They were cultured in quarantine at the Florida Biological ControlLaboratory, Gainesville, Florida, for 1 generation before shipment to California in thesummer of 1991. The dioecious hydrilla tubers were obtained from the USDA AquaticPlant Management Laboratory, Ft. Lauderdale, Florida. Known numbers of hydrillatubers were exposed to different numbers of

B. affinis

larvae. Eggs were used to ini-tiate the experiments because placing eggs on the soil surface more closely reflects ac-tual field conditions in which adults are released and allowed to oviposit. Eggs arealso more amenable to transfer to experimental containers than neonate larvae. Ofthe eggs used in these experiments, approximately 90% hatched (K. E. G., unpub-lished data).

Fifty replicates of each of the following egg to tuber ratio treatments were estab-lished: 1:5 (2 eggs: 10 tubers), 1:4 (2 eggs: 8 tubers), 1:2 (2 eggs: 4 tubers), 1:1 (2 eggs:2 tubers), 2:1 (4 eggs: 2 tubers), and 5:1 (10 eggs: 2 tubers). These treatments repre-sent the following tuber densities: 10 tubers, 3,306 per m

2

; 8 tubers, 2,645 per m

2

; 4 tu-bers, 1,323 per m

2

; and 2 tubers, 662 per m

2

. The treatments describe the initialexperimental conditions. Each replicate consisted of a plastic rearing container (5.5 x5.5 x 6 cm) filled with a sandy loam soil that had been moistened with a 1% benomyl

482



solution until damp, but friable. The benomyl solution was used to prevent the growthof fungi (Bennett & Buckingham 1991). Hydrilla tubers were weighed individually,and the required number buried approximately 3 cm below the soil surface.

B. affinis

eggs were dissected from water-soaked wood (an oviposition media) that had beenplaced in a colony cage for 24-48 h. The appropriate number of eggs was placed onmoist filter paper on the soil surface, and the container was covered with foil to main-tain soil moisture. Controls were set up exactly like the experimental containers, ex-cept that no eggs were included. Thirty-five replicates were set up as controls for eachof the four tuber densities in the six treatment ratios (i.e., tuber density of 10 for the1:5 ratio; 8 for the 1:4 ratio; 4 for the 1:2 ratio; and 2 for the 1:1, 2:1, and 5:1 ratios).All containers, both treatments and controls, were held at 27

°

C for 25 days. The con-tainers were misted 3 times per week with tap water to maintain soil moisture.

To determine germination of the tubers, all

B. affinis

and tubers were recoveredand counted. The tubers were then broken in half medially. The interior of each tuberwas examined and scored according to the following feeding damage scheme: 0, 1-25,25-50, 50-75, and 75-100% of the interior damaged. The tubers were then grouped ac-cording to treatment, replicate, and feeding damage category, and placed in petridishes (9 cm diam). The tubers were covered with tap water and placed at 27

°

C witha photoperiod of 16:8 (L:D) for 7 days. Under these conditions, any non-dormant tu-bers capable of germinating should have germinated (Spencer & Anderson 1986).

The effect of breaking the tubers in half medially on germination was investigatedby examining the germination of 100 tubers, 50 broken, and 50 left entire. The tuberswere placed in petri dishes (9 cm diam), covered with tap water, and held for 7 daysat 27

°

C with a photoperiod of 16:8 (L:D). The number of tubers germinating was re-corded.

Comparisons of the proportion of tubers in each feeding damage category amongratio treatments were done using

Χ

2

analysis (Steel & Torrie 1960). The effect of tubersize on the amount of feeding damage was investigated by assigning tubers to one offive size classes (0.10 - 0.15 gm, 0.16-0.20 gm, 0.21 -0.25 gm, 0.26 - 0.30 gm, or 0.31 -0.35 gm) and comparing the proportion of tubers in each feeding damage categoryamong size classes. This comparison was done using

Χ

2

analysis (Steel & Torrie 1960).The proportion of tubers germinating among ratio treatments, between ratio treat-ments and controls, among feeding damage categories, and between broken and en-tire tubers were compared using

Χ

2

analysis (Steel & Torrie 1960).

R

ESULTS

The number of

B. affinis

adults produced increased with an increase in the egg totuber ratio treatment (Table 1). The treatments were set up with differing numbersof eggs, so the proportion of adults produced were compared among treatments. Sig-nificantly lower proportions of adults were produced at the 5:1, 2:1, and 1:1 treatmentratios than at the 1:5, 1:4, and 1:2 treatments (Table 1;

Χ

2

=39.02, df=5, P<0.05). Thislower production of adults may be due to greater intraspecific competition among thelarvae. Such competition could result in greater mortality of the larvae in the highertreatments as compared with the lower treatment ratios, even though the larvae arenot cannibalistic (Bennett & Buckingham 1991).

The proportion of tubers fed upon increased with an increase in the egg to tubertreatment ratio (Fig. 1A;

Χ

2

= 91.1, df=5, P<0.01). The proportion of tubers damagedwas found to be independent of the weight of the tuber (Table 1;

Χ

2

=6.1, df=4, P>0.10),suggesting that the increase in damage was the result of an increase in the numberof larvae present. The proportions of tubers withinthe feeding damage categories dif-

Godfrey & Anderson:

B. affinis

& Hydrilla Tubers

483

fered significantly among the egg to tuber treatment ratios (Fig. 1B;

Χ

2

=304.6, df=20,P<0.01). At the low treatments (1:5), more of the tubers were in the no or low (0%, 1-25%) feeding damage categories, whereas, at the higher treatments, more tubers werefound in the higher feeding damage categories (50-75%, 75-100%; Fig. 1B).

Germination of the tubers was not influenced by breaking the tubers in half medi-ally (

Χ

2

=2.38, df=1, P>0.10). Of the tubers that were broken in half, 64% (n = 50) ger-minated. Of the tubers left entire, 78% (n = 50) germinated.

Comparisons of the proportion of tubers germinating in the treatments with thosein the controls summed over all feeding damage categories revealed significant differ-ences (Fig. 2A; 1:5:

Χ

2

=45.39, df=1, P<0.01; 1:4:

Χ

2

=15.76, df=1, P<0.01; 1:2:

Χ

2

=9.91,df=1, P<0.01; 1:1:

Χ

2

=14.69, df=1, P<0.01; 2:1:

Χ

2

=14.69, df=1, P<0.01; 5:1:

Χ

2

=14.96, df=1, P<0.01). In all egg to tuber treatment ratios, except the 1:2 treatment,the proportion of tubers germinating was less in the treatments than in the controls(Fig. 2A). This demonstrated the ability of

B. affinis

to reduce tuber germination. Inthe 1:2 egg to tuber treatment ratio, a greater proportion of tubers germinated in thetreatment than in the control (Fig. 2A). The reason for this difference is unclear. How-ever, in this treatment, the proportion of tubers germinating in all feeding damagecategories was greater than in other treatments (Fig. 2B).

In general, there was a reduction in tuber germinationwith an increase in the den-sity of

B. affinis

and the amount of feeding damage (Figs. 2A, 2B, and 3). Comparisonof the proportion of tubers germinating among egg to tuber treatment ratios withoutregard to feeding damage category, revealed a significant decrease in germination asthe treatment ratio increased (Fig. 2A;

Χ

2

=71.0, df=5, P<0.05). The proportion of tu-bers germinating in the controls and in each feeding damage category, regardless ofratio treatment, decreased significantly with an increase in damage category (Fig. 3;

Χ

2

=101.58, df=5, P<0.01). The proportion of tubers germinating decreased substan-tially for those tubers in the 25-50 and 50-75% feeding damage categories. No tubersgerminated in the 75-100% feeding damage category (Fig. 3).

D

ISCUSSION

The results suggest that for

B. affinis

to decimate hydrilla tuber banks, theyshould be released with an egg to tuber ratio of 2:1 or greater. The objectives of the re-lease should dictate the ratio used. For example, if

B. affinis

was used in an inocu-lative release program where establishment of the weevil was the objective, the egg totuber ratio for release should be 1:1 or 2:1. These lower ratios should be used because

T

ABLE

1. T

HE

MEAN

WEIGHT

±

STD

.

ERR

.

OF

TUBERS

,

THE

MEAN

NUMBER

±

STD

.

ERR

.

OF

B

.

AFFINIS

ADULTS

PRODUCED

AND

THE

PROPORTION

OF

EGGS

SURVIVING

TOTHE

ADULT

STAGE IN EACH RATIO TREATMENT.

Ratio TreatmentsMean Wt. of Tubers (gm)

Mean No. of B. affinis Produced

Proportion of Eggs Surviving To Adult

1:5 0.21 ± 0.003 0.7 ± 0.01 0.351:4 0.21 ± 0.003 0.62 ± 0.01 0.311:2 0.22 ± 0.004 0.84 ± 0.13 0.421:1 0.25 ± 0.007 0.50 ± 0.10 0.252:1 0.22 ± 0.005 0.86 ± 0.14 0.225:1 0.23 ± 0.007 1.76 ± 0.29 0.18


Fig. 1. A.) The proportion of tubers that had been fed upon or not fed upon for the1:5 (n = 500 tubers), 1:4 (n = 399 tubers), 1:2 (n = 200 tubers), 1:1 (n = 99 tubers), 2:1(n = 99 tubers), and 5:1 (n = 100 tubers) egg to tuber ratio treatments. Please note 1tuber was unaccounted for in the 1:4, 1:1, and 2:1 treatments. The proportion of tu-bers fed upon increased significantly (P < 0.01) with an increase in the ratio treat-ment. B.) The proportion of tubers in each feeding damage category in which feedingdamage occurred for each treatment. The proportion of tubers within feeding damagecategories differed significantly (P < 0.01) among the ratio treatments.

Godfrey & Anderson: B. affinis & Hydrilla Tubers 485

Fig. 2. A.) The proportion of tubers germinating in the controls and in each ratiotreatment. There was a significant decrease (P < 0.05) in germination with an in-crease in ratio treatment. Within each ratio treatment, the proportion of tubers ger-minating differed from that in the controls (P < 0.01). (See text for Χ2 values). B.) Theproportion of tubers germinating in each feeding damage category for each treatment.


they resulted in proportionally more adults being produced from the eggs than the 5:1egg to tuber ratio. However, if B. affinis was used in an inundative release programwhere the objective was maximum tuber destruction, then the egg to tuber ratio forrelease should be 5:1 or greater. The higher egg to tuber ratio should be used becauseproduction of adult B. affinis would not be a priority.

The egg stage of B. affinis may not be the most convenient life stage for release inthe field. Conversion of the number of eggs to the number of adults requires knowl-edge of the mean fecundity, the sex ratio of a population of weevils, and the percentegg eclosion. For B. affinis in the laboratory, the mean fecundity is 231.7 eggs per fe-male (Bennett & Buckingham 1991), the sex ratio is approximately 1:1 (Bennett &Buckingham 1991), and approximately 90% of all eggs hatch (K. E. G., unpublisheddata). To achieve a 2:1 egg to tuber ratio at a site would require 1 weevil for every 52tubers, assuming that the life history attributes for B. affinis given above are repre-sentative of those in the field. For the 5:1 egg to tuber ratio, 1 weevil would be re-quired for every 21 tubers.

In hydrilla-infested aquatic sites in Florida and California, tuber densities rangedfrom 0-510 and 20-1,000 tubers per m2, respectively (Bowes et al. 1979, Anderson &Dechoretz 1982, Sutton & Portier 1985). Reduction of the tuber banks in infested sitesin Florida using B. affinis would have required the release of between 0.1 - 10 weevilsper m2 to achieve the 2:1 egg to tuber ratio, and between 0.1 - 25 weevils per m2 for the5:1 ratio. In California, between 1 - 20 weevils per m2 would have to be released for the2:1 ratio, and between 1 - 48 weevils per m2 for the 5:1 ratio.

In practice, the number of weevils released should probably be greater than thosegiven above because the weevils may not be as successful in the field as they are in the

Fig. 3. The proportion of tubers germinating in each feeding damage categorysummed over the controls and all egg to tuber ratio treatments. There was a signifi-cant (P < 0.01) decrease in germination with an increase in feeding damage category.

Godfrey & Anderson: B. affinis & Hydrilla Tubers 487

laboratory. In two other studies where B. affinis was released in the field, the percentof tubers attacked was not as great as that in the laboratory. In Florida, B. affinis wasreleased at an egg to tuber ratio of about 1:5. In the tubers recovered from these sites,0 - 16.6% had been fed upon (Buckingham et al. 1994). In California, B. affinis was re-leased at an egg to tuber ratio of approximately 1.2:1, and 11.2% of the sentinel tubers(tubers that were placed in the field to monitor the success of a release) were fed upon(Godfrey et al. 1994). In this laboratory study, 37.2 and 52.5% of the tubers had beenfed upon in the 1:5 and 1:1 ratios, respectively. The lower rate of larval attack in thefield may have been due to a variety of factors such as soil temperature, soil texture,or movement by the adults before oviposition (Buckingham et al. 1994).

The ratios of weevils to tubers required for maximum tuber destruction deter-mined in this study should be viewed as guidelines for release numbers. Many factorsinfluence the ability of B. affinis to destroy tubers. However, the results of this studysuggest that under favorable conditions, B. affinis has the ability to impact hydrillatuber banks.

ACKNOWLEDGMENTS

We acknowledge K. Steward for supplying many of the hydrilla tubers used in thisstudy and D. Davis for her technical assistance. We thank S. Sheldon, F. Ryan, and L.Godfrey for reviewing an earlier draft of this manuscript. This research was sup-ported with a grant from California Department of Food and Agriculture.

Mention of a proprietary product does not constitute an endorsement or a recom-mendation for its use by USDA.

REFERENCES CITED

ANDERSON, L.W.J., AND N. DECHORETZ. 1982. Growth, reproduction and control ofHydrilla verticillata (L.f.) Royle in an irrigation system in the southwesternU.S. Proc. EWRS 6th Symposium on Aquat. Weeds. pp. 54-61.

BALOCH, G.M., SANA-ULLAH, AND M.A. GHANI. 1980. Some promising insects for thebiological control of Hydrilla verticillata in Pakistan. Trop. Pest Manage. 26:194-200.

BENNETT, C.A., AND G.R. BUCKINGHAM. 1991. Laboratory biologies of Bagous affinisand B. laevigatus (Coleoptera: Curculionidae) attacking tubers of Hydrilla ver-ticillata (Hydrocharitaceae). Ann. Entomol. Soc. America 84: 420-428.

BOWES, G., A.S. HOLADAY, AND W.T. HALLER. 1979. Seasonal variation in the biom-ass, tuber density, and photosynthetic metabolism of hydrilla in three Floridalakes. J. Aquat. Plant Manage. 17: 61-65.

BUCKINGHAM, G.R. 1988. Reunion in Florida - hydrilla, a weevil, and a fly. Aquatics10: 19-25.

BUCKINGHAM, G.R., C.A. BENNETT, AND E.A. OKRAH. 1994. Temporary establishmentof the hydrilla tuber weevil (Bagous affinis) during a drawdown in north-cen-tral Florida. J. Aquat. Plant Manage. 31: (in press).

GODFREY, K.E., L.W.J. ANDERSON, S.D. PERRY, AND N. DECHORETZ. 1994. Overwin-tering and establishment potential of Bagous affinis (Coleoptera: Curculion-idae) on Hydrilla verticillata (Hydrocharitaceae) in northern California.Florida Entomol. 77: 221-230.

SPENCER, D.F., AND L.W.J. ANDERSON. 1986. Photoperiod responses in monoeciousand dioecious Hydrilla verticillata. Weed Sci. 34: 551-557.

STEEL, R.G.D., AND J.H. TORRIE. 1960. Principles and procedures of statistics.McGraw-Hill Book Company, Inc. New York. 481pp.


SUTTON, D.L., AND K.M. PORTIER. 1985. Density of tubers and turions of Hydrilla inSouth Florida. J. Aquat. Plant Manage. 23: 64-67.

VAN, T.K., AND K.K. STEWARD. 1990. Longevity of monoecious hydrilla propagules. J.

♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦

Aquat. Plant Manage. 28: 74-76.

488



THREE NEW SPECIES OF RHYPAROCHROMINE LYGAEIDAE (HEMIPTERA: HETEROPTERA) FROM HISPANIOLA

J

AMES

A. S

LATER

1

AND

R

ICHARD

M. B

ARANOWSKI

2

1

Dept. Ecology & Evolutionary BiologyUniversity of Connecticut

Storrs, CT 06269

2

University of Florida Institute of Food and Agricultural SciencesTropical Research and Education Center

Homestead, FL 33031

A

BSTRACT

Three new species of rhyparochromine Lygaeidae, of the tribe Myodochini,

Her-aeus caliginosus

New Species

,

Heraeus concolor

New Species

, and

Catenes spiculus

New Species

from Hispaniola are described.

H. caliginosus

and

C. spiculus

are fig-ured.

Catenes

Distant has previously been known only from a single Central Ameri-can species.

Key Words: West Indies, Myodochini,

Heraeus

,

Catenes

R

ESUMEN

Se describen tres nuevas especies de Lygaeidae rhyparochromine, de la tribu Myo-dochini,

Heraeus caliginosus

Nueva Especie

,

Heraeus concolor

Nueva Especie

y

Catenes spiculus

Nueva Especie

colectados en Española. Se proveen figuras de

H.caliginosus

y de

C. spiculus

. El género

Catenes

Distant se

conocía

previamente en

base a una sola especie Centroamericana.

During the course of our ongoing study of the lygaeid fauna of the West Indies, wehave had occasion to study several interesting specimens taken in light traps in theDominican Republic. Several of these specimens represent undescribed species of thetribe Myodochini that are treated below.

The genus

Heraeus

Stal is a complex taxon with four species previously knownfrom the West Indies (Slater 1964).

Catenes

Distant, however, has been known previ-ously only from a single Central American species,

Catenes porrectus

Distant (Distant1893).



, Vol. 77, No. 4 (1994).

FEO




Slater & Baranowski: New Species of Lygaeidae (Hemiptera)

489

One of the striking features of these new species is that all of them show a con-trastingly dark and light color pattern. This is also true for a species of

Ozophora

(tribe Ozophorini) which will be discussed in a later paper. This convergence of colorpattern in what are otherwise unrelated taxa must be an adaptation to a substratewhich will only be clarified when material can be taken

in situ

in the field.All measurements are in millimeters.

Catenes spiculus

Slater and Baranowski,

New Species

(Fig. 1)

DESCRIPTION: Elongate, nearly parallel-sided. Head black, shining. Anteriorpronotal lobe dark chestnut brown with a black median stripe running through entirepronotum and scutellum. Anterior pronotal collar reddish brown, concolorous withposterior pronotal lobe. Posterior pronotal lobe reddish brown on either side of blackmidline, becoming darker reddish brown laterally. Scutellum dark chocolate brownwith a median black stripe, apex white. Hemelytra nearly uniformly testaceous withpunctures strongly constrastingly dark brown; lateral corial margins pale yellow; co-rium posteriorly with an apical dark brown macula and a second macula laterally notreaching lateral margin of corium, located at level of middle of apical corial margin.Membrane fumose with veins contrastingly white. Thoracic pleura and sterna darkchocolate brown, almost black. Abdomen bright reddish brown. Legs white, or paleyellow, with distal third of meso- and metafemora and distal half of forefemorastrongly contrastingly dark brown. Labium pale yellow. Antennae with first segmentchocolate brown, second segment pale yellow with extreme distal end infuscated,third segment pale yellow on proximal two thirds, but with an extensively developeddark brown distal third, fourth segment with base and apical third dark chocolatebrown, remainder of segment white. Dorsal surface clothed with upstanding hairs.Pronotum and scutellum dull, strongly contrasting with shining surface of head.

Head extremely elongate and tapering, apex exceeding distal end of first antennalsegment. Eyes sessile, set midway along lateral margins of head, remote from ante-rior pronotal margin. Length head 1.36, width 0.92, interocular space 0.36. Pronotumwith a distinct anterior collar, anterior lobe much narrower than posterior, transverseimpression complete. Length pronotum 1.30, width 1.60. Scutellum lacking a promi-nent median carina, although mesal area somewhat elevated. Length scutellum 1.02,width 0.76. Hemelytra with corium nearly parallel sided, slightly concave at level ofapex of scutellum. Length claval commissure 0.90. Midline distance apex clavus toapex corium 1.28. Midline distance apex corium to apex abdomen 1.06. Metathoracicscent gland auricle directed slightly postero-laterad, short, subelliptical. Evaporativearea large, occupying most of anterior lobe of metapleuron, narrowing posteriorly andextending anteriorly onto posterior area of mesopleuron. Mesepimeron emergent.Forefemora relatively slender, slightly incrassate, armed below distally with a simpleseries of spines as follows: two major spines with three minor spines between them, aproximally placed hair spine and a single small distal spine. Labium elongate, extend-ing onto second abdominal sternum. First labial segment extending caudad beyondposterior margin of eye but not reaching base of head; second segment reaching be-tween forecoxae; third segment reaching or slightly exceeding metacoxae. Length la-bial segments I 1.04, II 1.24, III 1.24, IV 0.50. Antennae slender, fourth segmentnarrowly fusiform. Length antennal segments I 0.56, II 1.40, III 1.20, IV 1.20. Totalbody length 6.64.

HOLOTYPE. Female.

Dominican Republic

: Guanumo, Finca Goya, 30.V.1989(Gustavo Anzerro) (blacklight trap). In National Museum of Natural History(NMNH).

490



ETYMOLOGY. Referring to the sharp needle-like anterior end of the head.Distant’s (1893) original description of

Catenes porrectus

, the only previouslyknown species in the genus, is very short. It was described from Guatemala and Pan-ama and is known only from these locations. Distant’s (1893) color plate shows

C. por-rectus

differing from

C. spiculus

n. sp. in having a pale yellow first antennal segment,the forefemora yellow with dark dots over the entire surface, the darkened distal thirdof the meso- and metafemora interrupted by a pale yellow annulus, dark distal ends

Figure 1. Catenes spiculus Slater and Baranowski New Species.


491

to all tibiae, a reddish brown head and scutellum and lacking a subapical dark maculaalong the costal margin of the corium.

Catanes porrectus

is said to be 8 mm long.We have examined two males from Venezuela (Miranda EST. EXT. Rio Negro cr.

CAPAYA, 100 m. 17-19.VI.80) (in Universidad Central de Venezuela) which agreewith the figure and description of

C. porrectus

(Distant 1893) in all respects, exceptthat the meso- and metafemoral annuli are obscure, all femora have numerous blackspots, and the hemelytra are completely and uniformly yellowish.

Heraeus caliginosus


New Species

(Fig. 2)

DESCRIPTION. Coloration chiefly black to extremely dark brown. Head black,strongly shining. Pronotum and scutellum dull black, with two small yellow maculaon either side of midline on posterior lobe immediately behind transverse impression.Scutellum gray on anterior half, with a narrow black median stripe and an obliqueblack macula midway between meson and lateral margin on each basal half. Heme-lytra in large part dark chocolate brown. Clavus yellow on anterior two-thirds withcontrasting dark brown punctures, extreme base and distal third dark brown. Coriumyellowish basally, area at level of claval commissure interspersed with yellowish anddark brown. A large rectangular white macula distally on corium at level of middle ofapical corial margin, extending from costal margin nearly to apical corial margin, butnot actually attaining latter. Membrane dark brown, veins in part pale yellow, a veryconspicuous rectangular white bar mesally on apical third of membrane. Thoracicpleura and sterna uniformly dull black. Abdomen shining reddish brown, a quadrateyellow macula present along dorsal margin of sternum five. Entire forefemora anddistal halves of middle and hind femora dark chocolate brown, strongly contrastingwith white proximal halves of middle and hind femora. Tibiae and tarsi pale yellow,tibiae infuscated with brown at extreme proximal and distal ends. Labium pale yel-lowish brown. First antennal segment dark red-brown, second and third segments al-most uniformly yellow, segment three becoming ochraceous distally, fourth segmentdark brown with a short, narrow, inconspicuous, poorly differentiated, pale annuluson proximal third (figure exaggerates pale annulus). Dorsal surface with a few scat-tered upright hairs present, these more numerous and elongate on head and scutel-lum. Thoracic punctures weak, indistinct, those on clavus and corium larger andconspicuous.

Head elongate, porrect. First antennal segment slightly exceeding apex of tylus.Eyes placed near middle of head, area behind eyes characteristically constricted.Length head 1.34, width 0.88, interocular space 0.42. Pronotum with anterior collarnarrow dorsally becoming strongly widened ventrally (typical for genus). A row ofdeep conspicuous punctures on depression behind posterior margin of anterior collar.Anterior pronotal lobe moderately convex but not elevated to level of posterior lobe,transverse impression complete and punctate. Length pronotum 1.0, width 1.44.Length scutellum 0.92, width 0.72. Lateral corial margins nearly parallel-sided,slightly concave at level of apex of scutellum. Length claval commissure 0.56. Midlinedistance apex clavus to apex corium 1.24. Midline distance apex corium to apex abdo-men 0.98. Metathoracic scent gland auricle short, slightly curving posteriorly. Evap-orative area occupying inner two thirds of metapleuron. Forefemora stronglyincrassate, armed below with at least four major spines, distally with a series ofsmaller spines. Labium elongate, exceeding metacoxae, attaining middle of abdomi-nal sternum two (first visible segment), segment one almost reaching base of head,second segment extending onto anterior portion of mesosternum. Length labial seg-

492



ments I 1.08, II 1.20, III 0.60, IV 0.66 (approx.). Antennae conventionally terete,fourth segment narrowly fusiform. Length antennal segments I 0.58, II 1.16, III 1.10,IV 1.20. Total body length 5.76.

TYPES. Holotype. Female.

Dominican Republic

: Pedernales Prov., 21 km. N.Cabo Rojo, 19.VI.1976 (R. E. Woodruff) (blacklight trap). In Florida State Collectionof Arthropods. Paratype: 1 male.

Dominican Republic

: Barahona, 6 km. NWParaiso, Rio Nizao, 18-02N, 17-12W, 170 m. 25-26-VII-1990 (C. Young, J. E. Rawlins,S. A. Thompson). In Carnegie Museum.

ETYMOLOGY. Referring to the dark coloration of the body.

Heraeus caliginosus

n. sp. is most closely related to

Heraeus guttatus

(Dallas), thetwo species resembling one another closely in size and general body proportions.

Her-aeus caliginosus

may readily be distinguished from

H. guttatus

by the elongate la-bium which extends well onto the second abdominal segment. In

H. guttatus

thelabium extends, at most, only between the metacoxae. In

H. caliginosus

the first an-

Figure 2. Heraeus caliginosus Slater and Baranowski New Species.


493

tennal segment is chocolate brown and contrasts strongly with the pale yellow secondsegment; in

H. guttatus

both the first and second antennal segments are pale yellowand concolorous.

Heraeus caliginosus

has a quadrate white corial macula with the an-terior and posterior margins parallel (somewhat irregular in the paratype) and atright angles to the body length; in

H. guttatus

the subdistal pale macula has irregularmargins, the anterior margin being convexly, although irregularly, produced, whereasthe posterior margin of the macula is concave and the entire macula is orientedslightly antero-mesad from the lateral margin. In

H. caliginosus

the apex of the mem-brane has a large conspicuous white parallel-sided patch. In

H. guttatus

the mem-brane is often pale at the end, but the pale area does not form a large evenly parallel-sided patch.

Heraeus guttatus

has at most only a trace of a brown distal area on themesofemora and a pale brown distal one third to one half of the metafemora, whereas

H. caliginosus

has the distal two-thirds of both the meso- and metafemora dark choc-olate brown.

Heraeus caliginosus

is a very dark species predominately black in color, whereas

H. guttatus

is chiefly yellowish brown.Differences from the similarly colored

H. concolor

described below are discussedunder the latter species.

The other Antillean species are readily separable,

H. pulchellus

Barber and

H. ple-bejus

Stal are much smaller, pale testaceous to light tan species, and

H. triguttatus

(Guerin) is a strikingly-colored orange and black species.

Heraeus concolor


New Species

DESCRIPTION. Head, pronotum, scutellum, forefemora, distal annulus on mid-dle and hind femora, pleuron, sternum and abdomen black. Posterior pronotal lobewith humeral angles and four small spots adjacent to transverse impression yellow-ish. Scutellum with a darker narrow median stripe. Hemelytra variegated: clavuschiefly dark brown, but with anterior half of cubital vein and a small macula mesadof vein near base testaceous; corium with a small dark brown spot near base, a com-plete broad, dark, transverse fascia completely across corium on distal third, and adark apex beyond the prominent white subapical pale spot; a small pale spot presentnear inner angle of corium. Membrane black or dark chocolate brown with a conspic-uous white rectangular apical mesal patch and light brown veins. Second and thirdantennal segments sordid tan, distal end of 3rd segment dark brown as is fourth seg-ment except for a conspicuous white subbasal annulus. First antennal segment andfirst labial segment darkened. Head shining, contrasting strongly with dull surface ofpronotum and scutellum. Body sparsely clothed with scattered upright hairs andshort decumbent silvery hairs.

Head slightly declivent; neck short. Length head 0.94, width 0.84, interocularspace 0.42. Transverse pronotal impression deep, anterior lobe not swollen above levelof posterior lobe. Length pronotum 0.98, width 1.30. Scutellum lacking a median ca-rina. Length scutellum 0.84, width 0.76. Length claval commissure 0.50. Midline dis-tance apex clavus to apex corium 0.96. Midline distance apex corium to apex abdomen0.76. Metathoracic scent gland auricle straight, short. Evaporative area covering atleast inner half of metapleuron, its outer margin strongly rounded. Forefemora armedbelow with 3-4 large spines and several smaller ones. Labium extending posteriorlybetween mesocoxae. Length labial segments I 0.72, II 0.74, III 0.62, IV 0.24. Antennaeconventionally terete with hairs on segments 2 and 3 longer than diameter of seg-ments. Length antennal segments I 0.38, II 0.80, III 0.64, IV 0.82. Total body length4.31.

HOLOTYPE. Female.

Dominican Republic

: Bayaguana. 4.IX.1991 (D. Brown)(blacklight trap). In National Museum of Natural History (NMNH).

494



ETYMOLOGY. Referring to a similarity in coloring (to

H. caliginosus

).It is unfortunate that we have only a single female of this predominately black spe-

cies. The color patterns of

H. caliginosus

and

H. concolor

are remarkably similar, bothspecies having a dark head, pronotum and scutellum with a prominent pale annuluson the fourth antennal segment, a large black median stripe through the dark scutel-lum, a large rectangular white patch mesally at the apex of the hemelytral mem-brane, four small yellow spots on the posterior pronotal lobe immediately behind thetransverse impression, and predominately dark femora.

Heraeus concolor

has pale humeral pronotal angles, whereas the humeral anglesof

H. caliginosus

are completely dark. The subapical white corial macula of

H. caligi-nosus

is relatively block-like with both anterior and posterior margins complete,whereas in

H. concolor

the anterior margin of this subapical corial macula is deeplyinvaded by dark coloration so that it takes on a rather hook-like appearance.

While the color differences discussed above could well be variable, the structuraldifferences between these two species are greater than those between several otherspecies of

Heraeus

.

Heraeus caliginosus has a relatively much longer head with theeyes less produced outward from the surface of the head (Fig. 2) than does H. concolor.In H. caliginosus the head length is about 1/3 greater than the pronotal length (1.34-1.0), whereas in H. concolor the pronotum is slightly longer than the length of thehead (0.94-0.98). Heraeus caliginosus has much longer, sweeping antennae. Antennalsegments II and III are each longer than the pronotal length (length pronotum 1.0,length antennal segment II 1.16, III 1.10), whereas in H. concolor the length of thepronotum is appreciably greater than the length of either the second or third antennalsegments (length pronotum 0.98, length antennal segment II 0.89, III 0.64). Heraeuscaliginosus also has a much longer fourth antennal segment than does H. concolor. InH. caliginosus the length of the fourth antennal segment is more than 2 1/2 times(2.71) as great as the interocular distance, whereas in H. concolor the fourth antennalsegment is less than twice as long as the interocular distance (1.95). The labium is rel-atively very long in H. caliginosus as noted above in the discussion of its relationshipto H. guttatus. In H. concolor the labium is much shorter, extending only between themesocoxae rather than reaching onto the abdominal sternum.

The occurrence of two such similarly colored, yet structurally, different species onHispaniola once again demonstrates the complex past history of speciation on thisenigmatic island.

ACKNOWLEDGMENTS

We wish to extend our appreciation to Dr. R. E. Woodruff, Emeritus Entomologist(Florida Department of Agriculture and Consumer Services, Division of Plant Indus-try), Dr. Eduardo Osuna (Universidad Central de Venezuela) for the loan of material,Dr. Donovan Brown (Plantaciones Oscar de la Renta), Gustavo Anzerro (Finca Goya)for operating blacklight traps and Mr. Stephen Thurston for providing the illustra-tions.

Florida Agricultural Experiment Station Journal Series No. R-03606.

REFERENCES CITED

DISTANT, W.L. 1893. Rhynchota. Hemiptera-Heteroptera. Vol. I. Biol. Centrali-Amer-icana. London. Supp. pp. 378-462.

SLATER, J.A. 1964. A Catalogue of the Lygaeidae of the World. Vol. II. University ofConnecticut, Storrs, Ct.

The flow from this article and the following article are the same but the columnshave b een disconnected. Be careful not to cover text up with the column.

Slater &Baranowski:

Oxycarenus hyalinipennis

, West Indies

495

THE OCCURRENCE OF

OXYCARENUS HYALINIPENNIS

(COSTA) (HEMIPTERA: LYGAEIDAE) IN THE WEST INDIES

AND NEW LYGAEIDAE RECORDS FOR THE TURKS AND CAICOS ISLANDS OF PROVIDENCIALES AND NORTH CAICOS

J

AMES

A. S

LATER

1

AND

R

ICHARD

M. B

ARANOWSKI

2

1

Dept. Ecology & Evolutionary BiologyUniversity of Connecticut

Storrs, Ct. 06269

2

University of Florida Institute of Food and Agricultural SciencesTropical Research and Education Center

Homestead, Florida 33031

A

BSTRACT

A breeding population of


(Costa) is reported for the firsttime from the West Indies. Its distribution is discussed and information to distinguishit from other closely related species is given. Several additional lygaeids are reportedfor the first time from the islands of North Caicos and Providenciales.

Key Words: Cotton, introduced, West Indies, Caicos Islands.

R

ESUMEN

Se reporta por primera vez en las Indias Occidentales una población reproductivade


. Se discute su distribución y se brinda información conel fin de distinguir esta especie de otras especies relacionadas. Se reportan por pri-mera vez varias especies adicionales de lygaeidos en las islas de Caicos del Norte y

Providenciales.

The cotton seed bug,


(Costa), is a common and wide-spread species in the Old World tropics. It extends from the European side of the Med-iterranean throughout Africa where it has frequently been reported as injurious tocotton. Samy (1969) stated that it is a cosmopolitan species “occurring in the Palearc-tic, Oriental and Neotropical regions.” It is not entirely accurate to state that it is cos-mopolitan as it is unknown in the Nearctic Region and, as will be discussed below, isintroduced in the Neotropics.

In Africa, it is an abundant widespread species and often causes staining of cotton.The intensive study by Kirkpatrick (1923) remains the definitive work. Kirkpatrickand other workers have listed a long series of plants upon which

O. hyalinipennis

hasbeen found (see Slater 1964), but breeding records appear to be largely restricted toplants of the order Malvales. Samy (1969) summarized this literature asserting thatprobably the true host plants are confined to species of Malvaceae, Sterculiaceae andTiliaceae. He mentioned the following genera:

Abutilon

,

Cola

,

Eiodendron

,

Gossyp-ium

,

Malva

,

Sphaeralcea

,

Hibiscus

,

Pavonia

,

Sida

,

Dombeya

,

Sterculia

and

Trium-fetta

.



, Vol. 77, No. 4 (1994).

FEO




496



In the summer of 1991, the junior author and his wife collected on North Caicosfive nymphs of a lygaeid under a species of

Pluchea

(Asteraceae) that they had notpreviously seen in the West Indies

.

Despite several hours of assiduous ground search-ing and sweeping in the same area on subsequent days, no additional specimens weretaken. No malvaceous plants were evident in the immediate area. These specimenssubsequently molted into adults and proved to be

O. hyalinipennis

. On another col-lecting trip to North Caicos, one adult of

O. hyalinipennis

was collected on wild cottonwithin 1 km of the previous find. More recently

O. hyalinipennis

was collected at Clar-ence Town, Long Island, Bahamas.

These records represent the first known breeding populations of this potentiallydestructive insect in the West Indies. Although Henry et al. (1983) indicated that

O.hyalinipennis

had been intercepted at a U.S. airport on a citrus leaf in baggage fromthe Dominican Republic, plus a number of additional interceptions at U.S. ports of en-try, the above record is the only one that could possibly have originated from a West-ern Hemisphere source.


has been established in South America for many years.Although Samy (1969) claimed a cosmopolitan distribution, there is no doubt that thisspecies is an introduced member of the Neotropical lygaeid fauna. The genus

Oxycare-nus

is a large and diverse one in the Old World tropics (approximately 50 species ofwhich at least 33 are Ethiopian) but, other than

O. hyalinipennis

, is not known to oc-cur in the Western Hemisphere.


was present in Brazil asearly as 1917 (Costa Lima, 1922). Kormilev (1950) summarized the history of the spe-cies in the Western Hemisphere. Costa Lima (1940) stated that specimens were takenin northeastern Brazil in 1917 on “lagarta rosa” and that there were records of dam-age to cotton bolls. Slater (1964) listed published records for Argentina, Paraguay, andBolivia, as well as Brazil.

It is, therefore, not surprising that this common and mobile species should appearin the West Indies, but it is surprising that the first record should come from the smallisland of North Caicos. This suggests that although we have not collected it in ourrather extensive surveys on many islands in the West Indies, it will eventually proveto be more widespread in the islands.

There are several closely related species of

Oxycarenus

that can readily be con-fused with

O. hyalinipennis

and several of these feed on Malvaceous plants. To aid inaccurate identification of this species, the following comments are included to enableothers workers to readily separate it from closely related species that have blackheads and pronota and pale colored hemelytra. Several species, such as

O. albidipen-nis

Stal,

O. pallidipennis

(Dallas) and

O. congoensis

Samy, may readily be recognizedby the orange-red coloration of the first five abdominal segments. Samy (1969) de-scribed the species

O. nigricornis

, which he listed as widespread in Africa. He sepa-rated it from

O. hyalinipennis

because the antennae of this species were completelyblack whereas he believed

O. hyalinipennis

always had pale second antennal seg-ments. Slater (1972) synonymized

O. nigricornis

with

O. hyalinipennis

stating thatthe antennal coloration of

O. hyalinipennis

is variable within populations and rangesfrom completely black through shades of dark brown to almost completely pale.

Oxy-carenus bokalae

Samy is the species most likely confused with

O. hyalinipennis

. Bothare similarly colored, but

O. hyalinipennis

has the clavus either completely or in largepart pale testaceous to white, whereas in the clavus,

O. bokalae

is almost uniformlydark brown to black. The pygophore opening also differs in the two species. In

O.bokalae

the opening is broad with the side margins arcuate and triangularly taperingto a sharply or bluntly pointed distal end whereas in

O. hyalinipennis

the pygophoreopening tapers evenly to a triangular point. Slater (1972) figured both conditions. It

Slater &Baranowski:


, West Indies

497

should be noted that, despite its relatively recent description,

O. bokalae

is alsowidely distributed in Africa and has been reported from cotton (Samy, 1969).

The following Lygaeidae are new records for the North Caicos and ProvidencialesIslands.

North Caicos

:

Ochrimnus laevus

Brailovsky.

Paromius longulus

(Dallas).

Oedancala cladiumicola

Baranowski & Slater.

Craspeduchus pulchellus

(F.)

Ozophora umbrosa

Slater (previously reported from West and South Caicos(Slater,1987)).

Pseudopachybrachius vinctus

(Say).

Nysius raphanus

Howard.

Providenciales

:

Ochrimnus laevus

Brailovsky.

Oncopeltus fasciatus

(Dallas).

Ozophora divaricata

Barber.

Pseudopachybrachius basalis

(Dallas).

Craspeduchus pulchellus

(F.)

Lygaeus bahamensis

Barber & Ashlock (previously reported by Barber andAshlock (1960), from South and West Caicos).

A

CKNOWLEDGMENT

Florida Agricultural Experiment Station Journal Series No. R-03605.

R

EFERENCES

C

ITED

B

ARBER

, H.G.,

AND

P.D. A

SHLOCK

. 1960. The Lygaeidae of the Van Voast-AmericanMuseum of Natural History expedition to the Bahama Islands 1953. Proc. En-tomol. Washington 62: 117-124.

C

OSTA

L

IMA

, A. 1922. “Char. e Quint” 25: (2): 110-112.C

OSTA

L

IMA

, A. 1940. Insectos do Brasil Hemipteros II. Rio de Janeiro: Escuela Na-cional de Agronomia pp. 1- 351.

H

ENRY

, T.J.,

AND

B

IOLOGICAL

A

SSESSMENT

S

UPPORT

S

TAFF

1983. Pests not known tooccur in the United States or of limited distribution. No. 38 Cottonseed BugHemiptera: Lygaeidae


(Costa) USDA Animal andPlant Health Inspection Service, Plant Protection Quarantine APHIS 81-43. 1-6 pp.

K

IRKPATRICK

, T.W. 1923. The Egyptian cotton seed bug (


(Costa). Its Bionomics, damage and suggestions for remedial measures. Bull.Minist. Agric. Egypt Techn. Scient. Serv. 35: 107 pp.

KORMILEV, N. 1950. La subfamilia Oxycareninae Stal en la Argentina con la descrip-tion de una especie nueva (Hemiptera: Lygaeidae). Anales Soc. Cient. Argen-tina 149: 22-32.

SAMY, O. 1969. A revision of the African species of Oxycarenus (Hemiptera: Lyga-eidae). Trans. Royal Entomol. Soc. London 121S: Pt. 4: 79-165.

SLATER, J.A. 1964. A Catalogue of the Lygaeidae of the World. Vol. I. U. Connecticut,Storrs, Ct.

SLATER, J.A. 1972. The Oxycareninae of South Africa (Hemiptera: Lygaeidae. U. Con-necticut Occ. Papers Biol. Scien. Ser. 2 (7): 59-103.

SLATER, J.A. 1987. A revision of the Ozophora umbrosa complex in the West Indies. J.New York Entomol. Soc. 95: 414-427.

498



WHITE EYE AND YELLOW LARVA: MUTANTS IN

ANOPHELES STEPHENSI

LISTON (DIPTERA: CULICIDAE)

N. J

AYA

S

HETTY

1,2

, G

AYATHRI

P

RABHAKAR

1

, S

UDHIR

K

ARL

N

ARANG

3

, P. D

AVID

F

OGLESONG

2

,

AND

D

ENNIS

J. J

OSLYN

2

1

Centre for Applied Genetics,Bangalore University, J.B. Campus,

Bangalore, 560 056, India

2

Department of Biology,Rutgers University,Camden, NJ 08102

3

United States Department of Agriculture,Agricultural Research Service, Biosciences Research Laboratory,

P. O. Box 5674, State University Station, Fargo, ND 58105

A

BSTRACT

Two spontaneous mutants, white eye (

w

) and yellow larva (

y

), were isolated andcharacterized from the Bangalore (southern India) and Poona (western India) strains,respectively, of the malarial mosquito,

Anopheles stephensi

(Liston) (Diptera: Culi-cidae). The

w

mutation is a sex-linked recessive. The second mutant,

y

, is an autoso-mal recessive.

Key Words: Genetic mutants,

Anopheles stephenci

, malaria.

R

ESUMEN

Fueron aislados y caracterizados dos mutantes espontáneos, ojo blanco (

w

) y larvaamarilla (

y

), a partir de las cepas de Bangalore (sur de India) y Poona (oeste de India),respectivamente, del mosquito de la malaria,

Anopheles stephensi

(Liston). La muta-

ción

w

es recesiva y ligada al sexo. El segundo mutante,

y

, es autosomal recesivo.

Genetic studies of mosquitoes, especially of species and strains which are vectors,continue to be an essential component of genetic control strategies aimed at disrupt-ing the transmission of diseases. These alternative strategies for control require ge-netic characterizations of geographically isolated strains because any one controlmechanism must operate throughout the range of the target mosquito species. There-fore, genetic profiles of different geographical isolates can be used to predict the po-tential success of laboratory-altered strains intended for release into nativepopulations of mosquito vectors. Our laboratories are currently performing geneticstudies towards the eventual development of strains for genetic control of the vectorsof infectious diseases. These studies include the following: genetic fingerprinting oflaboratory and natural populations of malaria- and encephalitis-carrying mosquitoes;restriction mapping of mitochondrial genomes from diverse geographical isolates;characterization of disease-refractory strains; and the isolation and characterizationof Mendelian mutants.



, Vol. 77, No. 4 (1994).

FEO




Shetty et al.:

Anopheles stephensi

Mutants

499

Considerable progress has been made on the genetics and cytogenetics of

Anophe-les stephensi

Liston ( Diptera: Culicdae). These studies have been reviewed byKitzmiller (1976), Narang & Seawright (1982), and Parvez

et al

. (1985). We reporthere two morphological mutants of the mosquito,

An. stephensi

, one of the most im-portant vectors of malaria throughout India and in the Middle East. Both mutants areeasily distinguished from the wild-type phenotype, and the viability of the mutants isas good as that of the wild-type. Therefore, they are excellent genetic markers and canbe used for the design of strains for genetic control. The first mutant, white eye (

w

),from the Bangalore (southern India) strain of

An. stephensi

is sex-linked and reces-sive in females and hemizygous in males, as revealed by our crossing experiments. Itmay or may not be related to white eye reported for other strains of

An. stephensi

. Thesecond mutant, yellow larva (

y

), is autosomal and recessive and comes from the Poona(western India) strain. White eye contrasts readily with the brownish-black wild-typeeye color in this mosquito, and yellow larva is easily distinguished from the wild-typestraw-tan color.

M

ATERIALS

AND

M

ETHODS

Rearing

Both the Bangalore (southern India) and the Poona (western India) strains of

An.stephensi

were utilized in this study. All mosquito stages were maintained at 26

°

±

1

°

C and at a relative humidity of 75%

±

5% with a photoperiod of 14:10 (L:D). Adultswere kept in 20 cubic-inch cages containing 10% sucrose. Females were bloodfed onmice, and all eggs were deposited 70-80 hours after blood feeding in an enamel bowlwith water and a lining of filter paper. Larvae were reared in 25 x 30 x 6 cm whiteenamel pans containing tap water and fed commercial bakers’ yeast.

Isolation of Mutants

The white eye (

w

) mutant appeared spontaneously in the Bangalore colony of

An.stephensi

. Its phenotype is an entirely white eye in larvae, pupae, and adults thatcould be distinguished easily from the wild-type with the naked eye. The yellow larva(y) mutant appeared spontaneously in the Poona colony of

An. stephensi

. Its pheno-type is an entirely yellow larva except for black eyes. It is manifested in early third in-stars and persists throughout the fourth instar and pupal stage with the fourth instarshowing the most conspicuous color. Yellow larva (

y

) is also easily distinguishablefrom the wild-type with the naked eye, and both mutants are as viable and easy tomaintain as their wild-type counterparts.

Design of Crosses

Pure colonies of

w

and

y

were obtained by crossing mutant adults

inter se

. Severalgenerations of such crosses involving 25 adults of each sex in 8 cubic-inch cages werenecessary to obtain sufficient numbers of pure-breeding mutant mosquitoes.

For the inheritance studies, mass matings were made between the pure-bred mu-tants and pure-bred wild-types. Portions of the F

1

males and females were back-crossed to stocks of the pure-bred mutants, and the F

2

backcross progeny were scoredfor phenotypes and ratios. The remaining F

1

males and females were inbred to pro-duce the F

2

generation.

500



R

ESULTS

The mode of inheritance of white eye (

w

) and yellow larva (

y

) in

An. stephensi

wasdetermined using classical Mendelian crosses and analyses. White eye was deter-mined to be a sex-linked recessive in the homogametic female and hemizygous in theheterogametic male. Yellow larva was found to be an autosomal recessive trait withfull penetrance and uniform expression in both sexes, but the specific autosome in-volved (2N = 6) remains undetermined.

The data in Table 1 summarizes the crosses between the white-eyed strain and thewild-type strain. In cross 1 in which white-eyed males were crossed with wild-type fe-males, the F

1

progeny consisted of all wild type individuals. In the reciprocal crosses(cross 2) in which white-eyed females were crossed with wild-type males, F

1

progenyconsisted of wild-type females and males of the mutant phenotype. Backcrosses of theF

1

females from both crosses 1 and 2 mated with white males resulted in wild-typeand white-eyed females and males in a 1:1:1:1 ratio (crosses 4 and 5). When F

1

malesfrom cross 1 were mated to white females, the progeny consisted of wild-type femalesand white-eyed males (cross 3), whereas white-eyed females crossed to F

1

males fromcross 2 resulted in all white-eyed progeny (cross 6). In both crosses F

1

progeny wereinbred to obtain F

2

individuals. In the first cross among the F

2

progeny all femaleswere wild-type while in males both wild-type and white-eyed phenotypes were found(cross 7). In the second cross among the F

2

progeny both wild type and white-eyedphenotypes were found in a 1:1:1:1 ratio (cross 8).

The results of the crosses between yellow larva and wild type are given in Table 2which indicates all appropriate Chi-square values supporting our interpretation of

T

ABLE

1. M

ODE

OF

INHERITANCE

OF

MUTATION

WHITE

-

EYE

(

w

)

IN

A

NOPHELESSTEPHENSI

. X, Y = X

AND

Y

CHROMOSOMES

,

RESPECTIVELY

;

w

=

WHITE

EYE

;+ =

WILD

TYPE

.

Presumptive Parental Genotypes Progeny Phenotypes

Cross

/ ?/

+

/

w

?

+

?w

1 X+ × XwX+ (Wild type) Y- (White) 543 0 538 0

2 Xw × X+Xw (White) Y- (Wild type) 612 0 0 668

3 Xw × X+Xw (White) Y- (Wild type) 506 0 0 473

4 Xw × XwX+ (Wild type) Y- (White) 43 51 41 51


6 Xw × XwXw (White) Y- (White) 0 404 0 372

7 Xw × X+X+ (Wild type) Y- (Wild type) 229 0 150 155


Shetty et al.: Anopheles stephensi Mutants 501

the mode of inheritance of y as an autosomal recessive. None of the resulting F1 mos-quitoes in crosses 1 and 2 could be distinguished from the wild-type parents. The dom-inance of the wild-type was complete. The F1 heterozygotes were then backcrossedwith the mutants. The results of the crosses (3, 4, 5, and 6) fit the expected 1:1 ratioof wild-type to mutants. The F1 adults were inbred to yield F2 generations. Thesecrosses (7 and 8) also yielded the expected 3:1 ratio of wild-type to mutants.

DISCUSSION

An. stephensi is an important vector which has developed resistance to insecti-cides. Therefore, it is mandatory that alternative strategies for its control be devel-oped. Genetic control is one such strategy which requires basic geneticcharacterizations. We have recently reported several studies in these areas of our on-going characterizations of An. stephensi (Gayathri & Shetty, 1989, 1992a, 1992b; Sh-etty & Gayathri, 1989; Bhaskar & Shetty, 1992; Rao & Shetty, 1992).

The two mutants, w and y, described in this study represent excellent markers forthe extension of these kinds of studies. Traditionally, such morphological mutantshave been used to construct special genetic load strains containing chromosomaltranslocations or inversions (Pal & Whitten, 1974; Joslyn, 1980). In such strains, ge-netic markers indicate the presence of the chromosomal aberrations through eitheraltered linkage relationships or position effects of genes located close to chromosomalbreakpoints. Genetic markers such as w and y also can be used in monitoring the pro-

TABLE 2. MODE OF INHERITANCE OF MUTATION YELLOW LARVA (y) IN ANOPHELESSTEPHENSI. *NOT SIGNIFICANT.

Number of Larvae

CrossesWild Type Yellow χ2

Cross No. / ? ? / Total ? / Total

1 ++ wild type ×

yy yellow 320 339 659 0 0 0 0

2yy yellow ×

++ wild type 202 177 379 0 0 0 0

3yy yellow ×

yy wild type 311 356 667 325 337 662 .0188*

4 y+ wild type × y

yyellow 272 256 528 249 244 493 1.199*

5 y+

wild type × yy

yellow 324 331 655 316 324 640 .1737*

6 yy

yellow × ++

wild type 198 201 399 190 187 377 .6237*

7 y+ wild type × y

+wild type 460 489 949 148 160 308 .1657*

8y+ wild type ×

y+ wild type 518 526 1044 168 178 343 .0541*


duction and maintenance of genetic sexing systems (Curtis et al., 1976; Kaiser et al.,1978; Shetty, 1987; Baker et al., 1981; Weller & Foster, 1993). More fundamentally,such genetic markers are necessary for expanding the linkage maps being establishedfor An. stephensi (Parvez et al., 1985).

Although the relatedness of w in the Bangalore strain to the w previously reported(Aslamkhan, 1973) in the Pakistani strain is unclear, the occurrence of the same phe-notypic mutant in such widely separated geographical isolates is, nevertheless, sig-nificant. The extent of genetic homogeneity among native strains of An. stephensi willaffect the ability of strains designed for genetic control to reduce natural populationsof this vector.

Previous studies of mutations in eye and larval colors in An. stephensi indicateconsiderable genetic variability in this species. For example, in addition to the sex-linked white eye mutant reported for the Pakistani strain (Aslamkhan, 1973), an au-tosomal, colorless mutant was reported by Sharma et al. (1977). These and other au-thors also described rosy eye (Aslamkhan & Gul, 1979) and red eye (Sharma et al.,1979). Chestnut eye (Rather et al., 1983), scarlet, pigmentless, and red-spotted mu-tants (Parvez et al., 1985) have also been reported in A. stephensi.

Larval color mutants of An. stephensi include green (Subbarao & Adak, 1981; Su-guna, 1981; Gayathri & Shetty, 1993), golden-yellow (Adak et al., 1990), black (Adaket al., 1990; Suguna, 1981; Shetty & Gayathri, unpublished data), stripe (Sakai et al.,1981; Shetty & Gayathri, unpublished data), greenish brown (Sharma et al., 1979),and brown (Shetty et al., unpublished data).

Of particular interest is the occurrence of the white eye mutation in the Bangalorestrain as a sex-linked locus. This was reported previously for the Pakistani strain inthe north (Aslamkhan, 1973) as well. Tests for allelism will be needed to verifywhether the same locus is present in these two widely separated populations. If thew locus is the same in both strains, then some degree of genetic homogeneity in An.stephensi may exist throughout its range, and this would be useful for future geneticcontrol efforts. If w involves different loci between strains, then the taxonomic statusof such strains needs to be clarified in greater detail as suggested by Subbarao et al.(1987) and Shetty et al., (unpublished). In the study by Subbarao et al. (1987) the au-thors refer to different races, historically, of An. stephensi and relate these forms tovectorial capacity. Nevertheless, they considered their data as consistent with An.stephensi having “ecological variants.”

Characterizations by classical cytogenetics along with the molecular approaches ofDNA fingerprint analyses and characterizations of mitochondrial genomes are inprogress in our laboratories. These integrated approaches could provide much infor-mation about the taxonomic status of geographical isolates and strains of An.stephensi.

ACKNOWLEDGEMENTS

This work was supported by a grant from U.G.C.-Departmental Special Assis-tance, the Indian Council of Medical Research, New Delhi, and a fellowship from theFulbright Foundation to N.J. Shetty.

REFERENCES CITED

ADAK, T., S.K. SUBBARAO, AND V.P. SHARMA. 1990. Genetics of golden-yellow larva inAnopheles stephensi. Mosq. News. 6: 672-676.

ASLAMKHAN, M. 1973. Sex chromosomes and sex determination in the malaria mos-quito, Anopheles stephensi. Pak. J. Zool. 5: 127-130.

Shetty et al.: Anopheles stephensi Mutants 503

ASLAMKHAN, M., AND R. GUL. 1979. Inheritance of the sex-linked mutant rosy, an al-lele of white in the malaria mosquito, Anopheles stephensi. Pakistan J. Sci. 31:245-249.

BAKER, R.H., R.K. SAKAI, AND K. RAANA. 1981. Genetic sexing for a mosquito sterile-male release. J. Hered. 72: 216-218.

BHASKAR, P., AND N. J. SHETTY. 1992. Susceptibility status of Anopheles stephensiListon to insecticides. J. Com. Dis. 26: 188-190.

CURTIS, C.F., J. AKIYAMA, AND G. DAVIDSON. 1976. A genetic sexing system in Anoph-eles gambiae species A. Mosq. News 36: 493-498.

GAYATHRI, D.K., AND N. J. SHETTY. 1989. Polytene chromosomes of Anophelesstephensi Liston - a malaria vector. Vigna Bharathi 12: 1-8.

GAYATHRI, D.K., AND N.J. SHETTY. 1992a. Chromosomal translocations and inheritedsemisterility in the malaria vector Anopheles stephensi Liston. J. Com. Dis. 24:70-74.

GAYATHRI, D.K., AND N.J. SHETTY. 1992b. Chromosomal inversions in Anophelesstephensi Liston - a malaria mosquito. J. Cytol. Genet. 27: 153-161.

GAYATHRI, D.K., AND N.J. SHETTY. 1993. Genetics of a larval colour mutant in Anoph-eles stephensi, a malaria vector. J. Cytol. Genet. 28: 105-106.

JOSLYN, D. 1980. The state of the art of genetic control of mosquitoes. Proc. New Jer-sey Mosq. Contr. Assoc. 67: 64-71.

KAISER, P.E., J A. SEAWRIGHT, D.A. DAME, AND D.J. JOSLYN. 1978. Development of agenetic sexing system for Anopheles albimanus. J. Econ. Entomol. 71: 766-771.

KITZMILLER, J.B. 1976. Genetics, cytogenetics and evolution of mosquitoes. Adv.Genet. 18: 315-433.

NARANG, S., AND J.A. SEAWRIGHT. 1982. Linkage relationship and genetic mapping inCulex and Anopheles, pp. 231-289 in W.W.M. Steiner, N.J. Tabachnick, K.S. Raiand S. Narang [eds.] . Recent developments in the genetics of insect diseasevectors. Stipes Publ. Co., Champaign, IL.

PAL, R., AND M.J. WHITTEN. [eds.]. 1974. The use of genetics in insect control.Elsevier/ North Holland, Amsterdam, Holland. pp. 241.

PARVEZ, S.D., K. AKHTAR, AND R.K. SAKAI. 1985. Two new mutations and a linkagemap of Anopheles stephensi. J. Hered. 76: 205-207.

RAO, G.D.E., AND N.J. SHETTY. 1992. Effect of insecticide resistance on reproductivepotential in Anopheles stephensi Liston, a malaria mosquito. Int. J. Toxicol. Oc-cup. Environ. Health 1: 48-52.

RATHOR, H.R., S. RASHID, AND TOQIR. 1983. Genetic analysis of a new sex-linked mu-tant - “chestnut eye” an allele of the white locus in the malaria vector Anophelesstephensi. Mosq. News. 43: 209-212.

SAKAI, R.K., M.P. IQBAL, AND R.H. BAKER. 1976. The genetics of stripe, a new morpho-logical mutant in the malaria mosquito, Anopheles stephensi. Canadian J.Genet. Cytol. 16: 669-675.

SHARMA, V.P., T.R. MANI, T. ADAK, AND M.A. ANSARI. 1977. Colorless-eye, a recessiveautosomal mutant of Anopheles stephensi. Mosq. News 37: 667- 669.

SHARMA, V.P., S.K. SUBBARAO, M.A. ANSARI, AND R.K. RAZDAN. 1979. Inheritancepattern of two new mutants, red-eye and greenish brown larvae, in Anophelesstephensi. Mosq. News. 39: 655-658.

SHETTY, N.J. 1987. Genetic sexing system for preferential elimination of females inCulex quinquefasciatus. J. Am. Mosq. Contr. Assoc. 3: 84-86.

SHETTY, N.J., AND D.K. GAYATHRI. 1989. Genetic control of mosquitoes: mating com-petitiveness of translocation heterozygote males of Anopheles stephensi Liston- a malaria vector in laboratory cage trials, pp. 41-45 in P.P. Reddy, [ed.], “Chro-mosome Damage by Environmental Agents”.

SUBBARAO, S.K , AND T. ADAK. 1981. Linkage relationship between three autosomalmutants and functional relationship beween two eye colour mutants in Anoph-eles stephensi. Indian J. Malar. 18: 98-102.


SUBBARAO, S.K., K. VASANTHA, T. ADAK, V.P. SHARMA, AND C.F. CURTIS. 1987. Egg-float ridge number in Anopheles stephensi: ecological variation and geneticanalysis. Med. Vet. Entomol. 1: 265-271.

SUGUNA, S.G. 1981. The genetics of three larval mutants in Anopheles stephensi. In-dian J. Med. Res. 73: 120-123.

WELLER, G.L., AND G.G. FOSTER. 1993. Genetic maps of the sheep blowfly Lucilia cu-prina: Linkage-group correlations with other dipteran genera. Genome 36:495-506.

Scientific Notes

505

AN EASILY-CONSTRUCTED TEMPORARY CAGE FOR STUDYING ANIMALS IN THE FIELD

M

ARTHA

D

UNHAM

Department of Entomology University of KentuckyLexington, KY 40546

Controlled experiments are easy to perform on animals in the laboratory, but un-natural conditions can cause behavioral artifacts. Studying animals in their naturalenvironment reduces artifacts, but makes precise control difficult. Large outdoor en-closures provide some of the advantages of each method of study; living conditions canbe controlled to a great extent, yet laboratory artifacts are less likely to affect the re-sults.

Recent advances in the study of dragonfly behavior, in particular, have been madepossible by the use of large flight cages (Michiels & Dhondt 1988, 1989). Return ratesfor dragonflies captured and released into the wild can be as low as 36% (Hilton 1983,1984). Experimentally-treated individuals released into a cage, on the other hand,can generally be recaptured (Michiels & Dhondt 1988). Studies of longevity, matura-tion processes (Michiels & Dhondt 1989, Dunham 1993b) and the effects of populationdensity (Dunham 1993a) are also possible in an enclosure.

In this note, I describe a method of constructing a large cage. The design is simple,the cage is easy to build in a short time, and it is sturdy enough to withstand 40-50mph winds (pers. obs.). I have successfully used this cage to observe behavior of

Pachydiplax

dragonflies at a pond (Dunham 1993b, 1994). In addition,

Calopteryx

damselflies survived several weeks at a section of a small stream enclosed by this cage(J. Waage, Brown Univ., pers. comm.). These large insects were unable to escape fromthe cage. Although, in general, small birds were unable to enter the cage, on occasionthey did get under the net if it was not sealed at ground level. If desired, minor mod-ifications could be made to keep birds in or out. Michiels & Dhondt (1988, 1989) builta taller enclosure covering the same area.

Figure 1. The completed flight enclosure, 10 m x 20 m x 3 m.



, Vol. 77, No. 4 (1994).

FEO




506



The materials needed to construct the cage are listed below. All measurements aregiven in both English and Metric units because construction materials in the U.S. arestill measured in English units.

PVC pipes, 3 cm (1 1/4 in) schedule 40 (thick-walled) PVC joints (if pipe comes without bell ends), 3 cm (1 1/4 in) EMT (galvanized metal electrical conduit), 2 cm (3/4 in) Nylon rope, 1.5 cm (1/2 in) Wooden stakes, 3 x 3 x 60 cm (1 in x 1 in x 2 ft) Cable ties (also called tie wraps), 18 cm (7 in) PVC glueSledge hammerPipe cap, 2.5 cm (1 in) and short length of 2.5 cm (1 in) pipeNetting, 360 m

2

(12 x 20 m plus endpieces); (4000 ft

2

or 40 x 65 ft plusendpieces). Netting should be UV resistant, not nylon; 10% shade-cloth works well. Sew together using nylon twine and large-eyed (tap-estry) needle.

S-hooks, 2.5 cm (1 in)

If a PVC midpole is used:

Drill bit, 1 cm (3/8 in)Carriage bolts, 7.5 x 1 cm (3 in x 3/8 in) Wing nuts, 1 cm (3/8 in)

Instructions for building a 10 x 20 x 3 m enclosure are as follows. Larger enclosurescan easily be constructed by adding more supports. For an enclosure 20 m long, 9cross-supports provided the sturdiest support, but 8 will still hold up the cage undermost conditions. The midpole (connecting the centers of the cross-supports) can berope or PVC pipe. PVC is sturdy but heavy. Rope is lighter and less expensive.

1. Glue together sections of PVC pipe to form 8 or 9 cross-supports 12 m (40 ft)long.

When bent into position, these will form the framework for a cage about 3 m highat the center.

2. While the glue is drying, cut sections of EMT into stakes 1.5 m (5 ft) inlength. These stakes are needed to hold the cross-supports in place. Drive the stakesinto the ground in 2 rows 10 m apart. If needed the end cap can be placed over the endof the pipe to prevent flaring of the pipe as it is driven into the ground. For 9cross-supports, the interval between stakes is 2.5 m (8.125 ft); for 8 cross-supports,the interval between stakes is 2.85 m (9.25 ft). The exact height of the EMT stakesabove ground is unimportant, but leave no more than one-half of the EMT protruding.

3. Attach the rope or PVC midpole to the cross-supports before erecting the en-closure. Tie or bolt the cross-supports (Fig. 2) at the appropriate distance apart toform the midpole. If the rope is used, make sure it is pulled taut so that the distancebetween cross-supports is the same as that between the stakes.

4. Slip ends of cross-supports over the ends of the EMT. The PVC ends will reston the ground.

5. Pull rectangular piece of netting across top of cage. 6. Use cable ties to attach netting to PVC near the ground.7. Sew hemicircular pieces of netting to netting covering the top to enclose the

ends of the cage. The netting can be left sewn together when the cage is disassembledso that the next time it is erected this step will be unnecessary. Leave a section openfor the entrance. The entrance can be held closed using S-hooks.

8. Stake edges of netting to ground, or cover edges with dirt. The latter may benecessary to keep birds out (or in).

Scientific Notes

507

9. Secure the midpole at ends of the cage with ropes. If the cage sags (especiallylikely if a PVC midpole is used) put a support under the upper end of each restrainingrope.

My heartfelt thanks to J. Ballard, who helped at every stage of the design andbuilding of the flight enclosure. N. Michiels also provided advice and assistance onconstruction, and on this manuscript. J. Waage, N. Michiels, C. Small, D. Lafferty, O.Reese, and A. Taylor helped build successive generations of the enclosure. This workwas funded by the Animal Behavior Society and the Sigma Xi Society.

S

UMMARY

An inexpensive and simple method is given for building a large outdoor cage. Thistype of enclosure can be erected quickly on most terrain, including over water.

R

EFERENCES

C

ITED

D

UNHAM

, M.L. 1993a. Fighting and territorial behavior in the dragonfly

Pachydiplaxlongipennis

. Brown University, Providence, R. I. Ph.D. dissertation.D

UNHAM

, M. 1993b. Changes in mass, fat content, and water content with growth inadult

Pachydiplax longipennis

(Odonata: Libellulidae). Canadian. J. Zool. 71:1470-1474.

D

UNHAM

, M. 1994. The effect of physical characters on foraging in

Pachydiplax lon-gipennis

(Burmeister) (Anisoptera: Libellulidae). Odonatol. 23: 55-62.

Figure 2. Detail of PVC midpole bolted to PVC cross-support.

508



H

ILTON

, D.F. J. 1983. Territoriality in

Libellula julia

Uhler (Anisoptera: Libellulidae).Odonatologica 12: 115-124.

H

ILTON

, D.F.J. 1984. Reproductive behavior of

Leucorrhinia hudsonica

(Selys) (Odo-nata: Libellulidae). J. Kansas. Entomol. Soc. 57: 580-590.

M

ICHIELS

, N.K.

AND

A.A. D

HONDT

. 1988. Direct and indirect estimates of sperm pre-cedence and displacement in the dragonfly

Sympetrum danae

(Odonata: Libel-lulidae). Behav. Ecol. Sociobiol. 23: 257-263.

M

ICHIELS

, N.K.

AND

A.A. D

HONDT

. 1989. Effects of emergence characteristics on lon-gevity and maturation in the dragonfly

Sympetrum danae

(Anisoperta: Libel-

♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦♦

lulidae). Hydrobiologia 171: 149-158.

508



A PRELIMINARY CHECKLIST OF THE ANTS (HYMENOPTERA: FORMICIDAE) OF EVERGLADES NATIONAL PARK

B

ETTY

F

ERSTER

1

AND

Z

ACHARY

P

RUSAK

2

1

Boston University Biology Department, Boston, MA 02215

2

University of Central Florida, Department of Biology, Orlando, FL 32816

Everglades National Park encompasses 602,616 ha within Dade, Monroe and Col-lier counties of southern, peninsular Florida. The Park contains varied habitat typesincluding rockland pine, mangrove swamp, hardwood hammock, freshwater slough,freshwater marl prairie, cypress swamp, and coastal prairie as well as marine and es-tuarine habitats (Everglades National Park official map and guide 1993).

The Everglades may function as a last refuge for rare and rapidly disappearingnatural communities. It also includes areas that were once managed for such diverseuses as cattle ranching and sugar cane production. The ant fauna, therefore, is likelyto be rich in indigenous species of natural habitats as well as species typical of dis-turbed sites, including exotics. The Everglades museum had representatives of onlyone species of ant (

Camponotus abdominalis floridanus

) from within park bound-aries. There is no published, comprehensive list of ants collected from within thisunique area. This study provides a preliminary catalogue of ant species of the Ever-glades and serves as groundwork for more thorough studies of ant ecology in the Park.

Ants were collected from: rockland pine along Research Road (Dade Co.); PalmaVista Hammock, a hardwood hammock near Anhinga Trail (Dade Co.); the disturbedarea surrounding the buildings of the Dan Beard Research Facility (Dade Co.); wet-land prairie at “Hole-in Doughnut”, 1 km SW of the research facilities (Dade Co.); wetflatwoods at Long Pine Key (Dade Co.); an interpretive trail that runs into wetlandprairie south of Pay-Hay-Okee (Dade Co.); Rowdy Bend, a mangrove swamp north ofFlamingo (Monroe Co.); coastal wetland surrounding the interpretive trail at EcoPond south of Flamingo Bay (Monroe Co.); and disturbed habitat within historicallyhardwood hammock at Flamingo (Monroe Co.). Collections were made from 1 June to31 June 1992 during both day and night. Dead twigs and sticks were split open to un-cover ant nests, bark was peeled from dead trees, and fallen logs were overturned tosearch for ants. Foraging ants were collected when found, and nests were excavatedto collect nest series. Alates and foragers attracted to lights were collected at night.



, Vol. 77, No. 4 (1994).

FEO




Scientific Notes

509

Leaf litter collected from hammock sites was placed in Berlese funnels for ant extrac-tion. Vouchers were deposited in the Everglades museum.

A literature search revealed ant species collected by other investigators within theEverglades. Additionally, the Archbold Biological Station database was searched forants collected within the Everglades and deposited in Archbold Biological Station andthe Smithsonian collections.

Forty-seven species of ants were collected from nine locations in six habitat typeswithin the park (Table 1). Our field efforts combined with the literature and database

T

ABLE

1. A

NT

SPECIES

COLLECTED

FROM

E

VERGLADES

N

ATIONAL

P

ARK

,

THE

HABITATSIN

WHICH

THEY

WERE

FOUND

AND

SOURCES

. HH =

HARDWOOD

HAMMOCK

;RP =

ROCKY

PINELAND

; CP =

COASTAL

PRAIRIE

; MG =

MANGROVE

; WP =

WESTLAND

PRAIRIE

; DI =

DISTURBED

; FS =

FRESHWATER

SLOUGH

.

Species HH RP CP WP MG DI FS

Aphaenogaster fulva

9

5

A. mariae

9

5

A. miamiana

1 6

Brachymyrmex depilis

6 6 6

B. minutus

6

B. obscurior

1 1 1 6

Camponotus caryae

9

3

C. abdominalis floridanus

1 1 1 1 6

C. decipiens

1, 6 6

C. (Colobopsis) impressus

1 1 1 6

C. pavidus

6

C. planatus

16

1

C. tortuganus

1 1

Cardiocondyla emeryi

16

1

C. nuda

16

1 1 1 6

C. venustula

16

1

C. wroughtonii

16

1, 6

Crematogaster ashmeadi

2 8 6 2 2

C. sp.

nr.

ashmeadi

(undescribed) 8

C. atkinsoni

1 6

C. minutissima

1, 4 6

Cyphomyrmex minutus

1 6 6

C. rimosus

16

8

Dolichoderus pustulatus

10

5

Dorymyrmex bureni

1 6

Eurhopalothrix floridana

6

Forelius pruinosus

1

Hypoponera opaciceps

3 6

510



H. opacior

1, 6

H. punctatissima

16

1

Leptogenys manni

6

Leptothorax torrei

1

L. allardycei

7

Linepithema humile

16

1

Monomorium floricola

16

1 1 6

M. minimum

9

5

M. pharaonis

16

1 1

Myrmecina americana

12

5

Odontomachus brunneus

13

4

O. ruginodus

16

1 6

Paratrechina bourbonica

16

1 1 1 6

P. guatemalensis

16

1 1 6

P. longicornis

16

1 1 1, 6

P. wojciki

6 6

Pheidole dentata

1, 8 1, 8 6 6

P. dentigula

6

P. floridana

6 5 6

P. megacephala

16

1

P. moerens

16

1, 6 1 6

P. morrisi

5

Platythyrea punctata 1 1P. cubaensis 1 6 6P. ejectus 6 1 6P. elongatus 6, 8 6 1P. mexicanus16 1, 6 1 1 1 6P. pallidus 1 1 1 1 6 6P. seminole 1 1P. simplex14 3, 5 6Quadristruma emmae16 1 6Smithistruma dietrichi 1, 6 6 6Solenopsis abdita 1 6S. geminata 1, 6, 8 8S. invicta16 1 1 1 1 1 1, 6S. tennesseensis 6 6Strumigenys eggersi16 1, 6

TABLE 1. (CONTINUED) ANT SPECIES COLLECTED FROM EVERGLADES NATIONAL PARK,THE HABITATS IN WHICH THEY WERE FOUND AND SOURCES. HH = HARD-WOOD HAMMOCK; RP = ROCKY PINELAND; CP = COASTAL PRAIRIE; MG =MANGROVE; WP = WESTLAND PRAIRIE; DI = DISTURBED; FS = FRESHWATER


Scientific Notes 511

searches revealed a total of 75 species. Twenty-six species were exotic. Fifteen of theexotic species originated from old world tropics and eleven originated from new worldtropics. Because unequal amounts of time were spent at each site and collecting meth-ods varied with each habitat type, these data cannot be used as a measure of habitatspecies abundance.

The Everglades is a large ecological preserve located at the southern tip of penin-sular Florida. It includes both pristine habitat and historically man-modified areas,and lies between two areas of relatively well-studied ant faunas: 1) the Florida Keys(Wilson 1964, Deyrup et al. 1988, Deyrup 1991), and 2) areas of southern Floridanorth of the Everglades (Smith 1930, Wheeler 1932, Smith 1933, Nielsson et al. 1971,Deyrup & Trager 1986).

Thirty-five percent of the species that have been collected within the Evergladeswere exotics and none of these species were restricted to disturbed habitats. However,because our collections from “natural” areas contained disturbances such as roadsidesand trails, these are effectively disturbed areas. The proportion of exotic species thatwere found in the Everglades was similar to the proportion of exotic species that havebeen found in the Florida Keys (Deyrup 1991), and similar to the proportion of exoticant species found in residential Dade county (Deyrup 1991).

S. gundlachi16 6 7 6S. louisianae 6 6Tapinoma litorale 1 1T. melanocephalum16 1 6T. sessile 6Tetramorium caldarium16 1 1, 6T. simillimum16 1Wasmannia

auropunctata16 1 1 1 1 6Xenomyrmex floridanus15 4 6Zacryptocerus varians 1 6

1Present study.2Nielsson et al. 1971.3Smith 1930.4Smith 1933.5Wheeler 1932.6Ants of Florida database, Archbold Biological Station collection and Smithsonian collection.7Smith 1979.8Koptur 1992.9Questionable record, specimens unavailable for verification (M. Deyrup, pers. comm.)10Listed as Dolichoderus plagiatus subsp. pustulatus in Wheeler 1932.11Listed as Ponera opaciceps in Smith 1930.12Listed as Myrmecina graminicola Latr. subsp. americana Emery var. Brevisponosa Emery in Wheeler 1932.13Listed as Odontomachus haematodes subsp. insularis Guerin in Smith 1933.14Listed as Pseudomyrma flavidula in Smith 1930, and Wheeler 1932.15Listed as Xenomyrmex stolli subsp. rufescens Wheeler in Smith 1933.16Exotic species.

TABLE 1. (CONTINUED) ANT SPECIES COLLECTED FROM EVERGLADES NATIONAL PARK,THE HABITATS IN WHICH THEY WERE FOUND AND SOURCES. HH = HARD-WOOD HAMMOCK; RP = ROCKY PINELAND; CP = COASTAL PRAIRIE; MG =MANGROVE; WP = WESTLAND PRAIRIE; DI = DISTURBED; FS = FRESHWATER



The present study did not extend the ranges for any native or exotic species. Nonew species were discovered. Many exotics were expected because of the neotropicalclimate and proximity to centers of commerce and human traffic. Future collections inpristine habitats, less prone to the invasions of some exotics, would be useful addi-tions to our knowledge of the ant assemblage of the Everglades.

Mark Deyrup (Archbold Biological Station) supervised ant identifications as wellas providing encouragement, support and endless hours of entertainment. No ac-knowledgment could exhibit the amount of gratitude and respect the authors have forDr. Deyrup. Alfredo Begazo, Jamie Prusak, Walter Meshaka, Jr., Lloyd R. Davis, Jr.,Marcia Moretta, Elizabeth A. Capaldi and an anonymous reviewer provided helpfulsuggestions to improve this manuscript.

SUMMARY

Forty-seven species of ants were found in six habitat types in Everglades NationalPark during nine collecting trips in June 1992. A search of both the literature and adatabase of Florida ants are combined with our efforts to form a preliminary list of 75species of ants from the park.

REFERENCES CITED

DEYRUP, M. 1991. Exotic ants of the Florida Keys, pp. 15-22 in W. Hardy Eshbaugh[ed.], Proceedings of the 4th Symposium on the Natural History of the Baha-mas. San Salvador, Bahamas.

DEYRUP, M., AND J. TRAGER. 1986. Ants of the Archbold Biological Station, HighlandsCounty, Florida. Florida Entomol. 69: 206-228.

DEYRUP, M., J. TRAGER, N. CARLIN, AND G. UMPHREY. 1988. A review of the ants of theFlorida Keys. Florida Entomol. 71: 163-176.

KOPTUR, S. 1992. Plants with extrafloral nectaries and ants in Everglades habitats.Florida Entomol. 75: 38-50.

NATIONAL PARK SERVICE. 1993. Everglades, Official map and guide. U.S. Dept. of theInterior. Washington, D. C.

NIELSSON, R.J., A.P. BAKTAR, AND H.A. DENMARK. 1971. A preliminary list of ants as-sociated with aphids in Florida. Florida Entomol. 54: 245-248.

SMITH, D.R. 1979. Superfamily Formicoidea. pp. 1323-1467 in K. V. Krombein, P. D.Hurd, D.R. Smith, and B.D. Burks [eds.], Catalogue of Hymenoptera in Amer-ica north of Mexico, vol. 2., Smithsonian Institution Press, Washington, D.C.

SMITH, M.R. 1930. A list of Florida ants. Florida Entomol. 14: 1-6.SMITH, M.R. 1933. Additional species of Florida ants, with remarks. Florida Entomol.

17: 21-26.WHEELER, W.M. 1932. A list of the ants of Florida with descriptions of new forms. J.

New York Entomol. Soc. 40: 1-17.WILSON, E.O. 1964. The ants of the Florida Keys. Breviora. 210: 1-14.

Scientific Notes

513

A CONTAINER FOR ECLOSION AND HOLDING ADULT INSECTS PRIOR TO MASS RELEASE

J.M. S

IVINSKI

, C.O. C

ALKINS

,

AND

R. B

ARANOWSKI

Insect Attractants, Behavior, and Basic Biology Research Laboratory,Agricultural Research Service, U.S. Department of Agriculture,

Gainesville, FL 32604

The mass release of adult insects requires containers for eclosing pupae and, attimes, for holding adults for several days (e.g., Tanaka boxes used in the release ofsterile fruit flies illus. in Holler, et al. 1984). These units can be both bulky and expen-sive. Casual observation of large numbers of confined insects has shown that the ma-jority of their time is spent resting on cage walls or on objects in the cage. The largeair volume of a cage is essentially wasted space. With this in mind, a container in theshape of a bag roughly the size of a pillow case was designed for eclosing and holdinglarge numbers of adult braconid parasites. The eclosion bag is mostly “walls,” takesup little room, and is easy to move about, both within the rearing/eclosion facility andduring transportation to release sites.

The bags are made from pieces of 32 x 32 nylon mesh screen (Lumite, Inc., Gaines-ville, GA.) that are sewn together and closed continuously across the bottom and thelength of one side by velcro strips. For our purposes, we found that a bag 60 cm wideand 90 cm long was ideal, but smaller as well as larger bags (up to 2m long) have beenconstructed, and insects have been successfully maintained in them. Earlier designshad rounded edges on the bottom to prevent insects from accumulating in corners and“milling.” The parasite being held in our research,

Diachasmimorpha longicaudata

(Ashmead), did not display this behavior to any significant extent, and bags withsquare-edges proved easier to sew and cheaper to produce. Should these bags beadapted for use with insects in which milling is typically a problem, e.g., tephritidfruit flies, the inclusion of rounded bottom corners might be considered.

During the holding/maturation period, parasites were fed a solution of honey andwater that was poured into 30 cm polyethylene tubes with an inner diam of 10 mm.The tube ends were closed with 3 cm cotton wicks. The diluted honey seeped throughthe wick and provided a feeding surface for the insects. To prevent either dripping orincomplete absorbance, we found it necessary to vary the proportions of honey andwater with changes in temperature and relative humidity. The tube was held alongthe upper margin of the bag with a large (#5) binder clip. Cages were then hung fromlines, sometimes at two levels in rooms of normal height (~ 2.5 m). An S-hook or openpaper clip fitted through the binder clip and then over the line made an effectivehanger.

Parasitized Caribbean fruit fly pupae (

Anastrepha suspensa (Loew))

were pouredevenly on the bottom of the bag. A typical volume was 375 ml, which gave rise to ap-proximately 5000 adult parasites.

For our needs, adults were maintained in the bags for five days after the first eclo-sion. They were then taken by vehicle to the release sites. Lines strung in the back ofa van provided a convenient method of suspending them during transportation, al-though bags could be laid flat and stacked several deep with no apparent ill effects onthe parasites.

At the release site, the feeding tube was removed, the velcro opened, and the pupalremains poured into a bucket. The bag was spread open and shaken in the air. Thiswas a particularly useful technique in releasing

D. longicaudata

, which have a rela-



, Vol. 77, No. 4 (1994).

FEO




514



Fig. 1. A bag cage being fitted with a feeding tube.

Scientific Notes

515

tively powerful grip and are often difficult to remove en masse from conventionalcages.

Adult survival in bag containers appeared similar to that in typical screen cagesduring a one-year-long augmented parasite release program in which 1 to 1.5 millionparasites per week were released. This was verified in a laboratory study that com-pared mortality in bag cages and 30 x 30 x 30 cm screen cages. Fifteen ml of irradiatedand parasitized pupae were put in five of each type of cage (Sivinski & Smittle 1990).The day on which the first adult in any particular cage eclosed was considered dayone. The numbers of live and dead insects were counted after five days. There was nosignificant difference in either emergence or mortality between the two types of con-tainers (t-test, SAS Institute, 1987);

×

live insects bag = 60.6 (SE=8.4) vs

×

live insectscages = 59.4 (5.8) df=8, t = 0.12, p = 0.91;

×

dead insects bag = 3.2 (0.92) vs

×

dead in-sects cage = 1.41 (0.37), df = 8, t = 1.41, p = 0.20.

The bags wear well during extended periods of use, although care needs to betaken to keep the velcro clean because dirt adhering to the velcro can prevent it fromclosing uniformly. Small open spots can be “mended” with a paper clip.

The portability of the bags has proven to be a particular asset. They are presentlybeing used in the mountains of Guatemala where thousands of insects are trans-ported into steep and thickly-vegetated areas that would otherwise be difficult toreach on foot.

We thank Julieta Brombilla, Pat Graham, Tim Holler, and Mikito Pena for helpingto guide the evolution of the bag.

S

UMMARY

A bag cage is described for holding and maintaining insects for use in mass releaseprograms. Field experience and data have shown that insect survival in this cage iscomparable to that in standard screen cages. In addition, the cage is easily portable,especially in hilly, heavily vegetated areas.

R

EFERENCES

C

ITED

H

OLLER

, T.C., J.L. D

AVIDSON

, A S

UAREZ

,

AND

R. G

ARCIA

. 1984. Release of Sterile Mex-ican Fruit Flies for Control of Feral Populations in the Rio Grande Valley ofTexas and Mexico. J. Rio Grande Hort. Soc. 37: 113-121.

SAS I

NSTITUTE

, 1987. User’s Guide. SAS Institute, Cary, N.C.S

IVINSKI

J.M.,

AND

B. S

MITTLE

. 1990. Effects of gamma radiation on the developmentof the Caribbean Fruit Fly (

Anastrepha suspensa

) and the subsequent develop-ment of its parasite

Diachasmimorpha longicaudata

). Entomol. Exp. Appl.55:295-297.

516



DEVELOPMENTAL RATES OF

BAGOUS AFFINIS

(COLEOPTERA: CURCULIONIDAE) AT CONSTANT

TEMPERATURES

K.E. G

ODFREY

,

AND

L.W.J. A

NDERSON

USDA Aquatic Weed Control Research LaboratoryVegetable Crops, 124 Robbins Hall

University of CaliforniaDavis, CA 95616

Bagous affinis

Hustache (Coleoptera: Curculionidae) is a biological control agentof


(L.f.) Royle (Hydrocharitaceae; hydrilla), a weed in ponds,lakes, and waterways. Adults feed on hydrilla stems and leaves that are left exposedas waters recede during the dry season or following a drawdown (Baloch et al. 1980).The adults oviposit in moist organic matter found in and among the exposed hydrillastems (Bennett & Buckingham 1991). The larvae burrow in the soil beneath the ex-posed stems and feed on subterranean vegetative propagules called tubers (Baloch etal. 1980). The basic life history and host range of

B. affinis

has been studied (Buck-ingham 1988, Bennett & Buckingham 1991). However, other aspects of the life historyof

B. affinis

need to be determined to assess its potential and optimize its use as a bi-ological control agent. For example, information on the rate of development of eachlife stage can be used to predict the best time for release (i.e., when air and soil tem-peratures are above developmental thresholds). In addition, the time of egg hatch orcompletion of the larval or pupal stage in the field after release and the number ofgenerations possible at a site in a given period of time can be estimated. Therefore, inthis study we measured the rate of development of the egg, larval, and pupal stagesat six constant temperatures and constructed simple linear thermal unit models. Therange of temperatures used represent those typical of northern California from latespring through fall, the dry season when aquatic systems undergo natural draw-downs (NOAA 1985).

The rates of development of the egg, larval, and pupal stages were estimated at 18,21, 25, 28, 30, and 32

°

C (

±

1

°

C) constant temperature regimes. The weevils used inthese experiments were maintained in laboratory culture for 8 to 14 generations andwere from the same colony as that described by Godfrey et al. (1994).

B. affinis

were reared individually in small, plastic containers (5.5 x 5.5 x 6.5 cm)to measure development at each temperature. Each container was filled with moistsoil (a fine sandy loam), and five dioecious hydrilla tubers were buried 3 cm beneaththe soil surface. Eggs were dissected from water-soaked wood (an oviposition sub-strate) that had been placed in colony cages for less than 24 hours. Each egg wasplaced on a piece of moist filter paper on the soil surface. The container was coveredwith aluminum foil to maintain humidity. The rearing containers were placed in agrowth chamber (Model CEC 36-10HLE, Rheem Sherer, Weaverville, NC) at the ap-propriate temperature regime, and checked once daily for egg hatch. The time of daythat the eggs were checked and the condition of the eggs (i.e., hatched or not hatched)were recorded.

The following number of eggs were placed at each temperature regime: 180 at18

°

C; 145 at 21

°

C; 181 at 25

°

C; 135 at 28

°

C; 130 at 30

°

C; and 293 at 32

°

C. Differingnumbers of eggs were used because the survivorship of

B. affinis

from egg to adultvaried with temperature. In addition, measurement of developmental rate was at-tempted at 15

°

C (n=20) and 35

°

C (n=60), but no

B. affinis

survived to the adult stage.



, Vol. 77, No. 4 (1994).

FEO




Scientific Notes

517

Upon egg hatch, the containers were not disturbed until most

B. affinis

were thirdinstars, except to mist the soil surface with tap water to maintain soil moisture. Thisperiod of no disturbance reduced the mortality imposed on first and second instars byhandling. The length of time from egg hatch through most of the larval stage (i.e., pe-riod of no disturbance) was determined by trial and error. For the 18

°

C regime, the pe-riod of no disturbance was 25 d; for 21

°

C, 15 d; for 25

°

C, 12 d; for 28

°

C, 7 d; for 30

°

C,5 d; and for 32

°

C, 3 d. After the period of no disturbance, the contents were sorted byhand to recover all

B. affinis

and tubers. Many of the

B. affinis

were inside the tubers,and most were third instar larvae, although a low percentage were pupae. For thoseindividuals that were pupae, development was measured from egg to adult only. Alllarvae and pupae found were placed individually in small petri dishes (5.5 cm diam)with tubers and some soil. The larvae and pupae were checked daily, and the life stageand time of day were recorded.

The length of time spent in each life stage was estimated because the exact timeof molting was not known (the insects were checked only once per day). Therefore, weassumed that any change in life stage occurred at the midpoint between two consec-utive daily checks. The length of time required for development from egg to adult wascalculated by adding the times required to complete the egg, larval, and pupal stages.The mean time required to complete each life stage and from egg to adult was calcu-lated for each temperature using the PROC MEANS (SAS Institute 1982). A simplelinear thermal unit model was constructed by regressing the mean developmentalrate of a life stage on temperature using simple linear regression (Steel & Torrie 1960;PROC REG, SAS Institute 1982). The mean developmental rate was defined as the re-ciprocal of the mean time required for completion of a life stage. The threshold tem-perature of each life stage was determined by extrapolation of the linear regressionline to the

x

-axis. The thermal units required to complete development were calcu-lated by first determining the number of thermal units required to complete develop-ment of a life stage at each temperature using:

DD = (T

1

- T

0

)Dev

where

DD

is the thermal units in Celsius degree-days,

T

1

is the experimental temper-ature (

°

C),

T

0

is the threshold temperature (

°

C), and

Dev

is the mean number of daysto complete a life stage (Arnold 1959, 1960). The mean thermal units required to com-plete development were then calculated for each life stage and for development fromegg to adult.

Weevils successfully completed development at 18, 21, 25, 28, 30, and 32

°

C (Table1). The percentage of eggs that survived to the adult stage was 5.6% at 18

°

C, 20.0%at 21

°

C, 16.0% at 25

°

C, 30.4% at 28

°

C, 18.5% at 30

°

C, and 8.2% at 32

°

C. At 15

°

C, 2 of20 eggs hatched; however, neither larva survived to the adult stage. Eggs hatched at35

°

C, but the individuals died early in the larval stage; little evidence of feeding wasobserved on the tubers.

The time for completion of all life stages of

B. affinis

was inversely related to tem-perature (Table 1). The mean time for egg hatch of

B. affinis

ranged from 3.0 d (32

°

C)to 11.3 d (18

°

C). For the larval stage, the mean development time ranged from 7.5 d(32

°

C) to 32.6 d (18

°

C), and for the pupal stage, from 3.3 d (32

°

C) to 11.9 d (18

°

C). Themean time for completion of development from egg to adult ranged from 13.7 d (32

°

C)to 55.6 d (18

°

C).From the thermal unit models, completion of the egg stage was calculated to re-

quire 56.7 degree-days above 12.7

°

C (Table 2). Larvae required 127.2 degree-daysabove 14.5

°

C, and pupae, 60.1 degree-days above 13.4

°

C (Table 2). The combined lifestages required 239.0 degree-days above 14.0

°

C (Table 2). The calculated thresholdtemperatures were slightly lower than the lowest temperature at which development

518



would not occur in this study (15

°

C). The lower calculated threshold temperatureswere probably due to the use of a linear equation to describe the non-linear relation-ship between temperature and rate of insect development (Wagner et al. 1984).

The simple linear thermal unit models derived in this study will be useful in future

B. affinis

release programs. The models provide information on the appropriate time

T

ABLE

1. M

EAN

NUMBER

OF

DAYS

±

STD

ERROR

(

N

=

NUMBER

OF

INDIVIDUALS

)

TO

COM-PLETE

EGG

,

LARVAL

,

AND

PUPAL

STAGES

AND

FROM

EGG

TO

ADULT

FOR

B.

AFFINIS

AT SIX CONSTANT TEMPERATURES.

Temperature (°C)

Stage 18 21 25 28 30 32

Egg 11.3 6.2 4.8 3.7 3.2 3.0± 0.17 ± 0.09 ± 0.08 ± 0.08 ± 0.05 ± 0.05

(n = 88) (n = 69) (n = 85) (n = 83) (n = 82) (n = 85)Larvae 32.6 20.7 13.5 8.2 8.4 7.5

± 1.11 ±0.48 ± 0.29 ± 0.13 ± 0.23 ± 0.19(n = 12) (n = 27) (n = 27) (n = 33) (n = 28) (n = 27)

Pupae 11.9 8.0 5.6 4.2 3.5 3.3± 0.79 ± 0.25 ± 0.21 ± 0.31 ± 0.17 ± 0.09(n = 9) (n = 25) (n = 25) (n = 29) (n = 24) (n = 24)

Egg to Adult 55.7 35.0 23.7 15.7 14.7 13.7± 1.51 ± 0.47 ± 0.33 ± 0.28 ± 0.35 ± 0.17

(n = 10)a (n = 29)a (n = 29)a (n = 41)a (n = 24) (n = 24)

aThe n value for egg to adult is greater than that for pupae due to differences in larval developmental rates. Only total development time from egg to adult was measured for those individuals that had reached the pupal stage when the contents of the rearing containers were sorted.

TABLE 2. STATISTICS GENERATED FROM REGRESSION ANALYSES OF MEAN B. AFFINIS DE-VELOPMENT RATE ON TEMPERATURE, AND THRESHOLD TEMPERATURES (T0),AND MEAN DEGREE-DAYS (DD; STD ERROR) REQUIRED FOR DEVELOPMENT OFEACH B. AFFINIS LIFE STAGE.

Y T0 DD

Stage Intercept Slope r2 Prob>F (°C) (°C-day)

Egg -0.23 0.018 0.99 0.0001 12.7 56.7(0.023) (0.0009) (1.27)

Larvae -0.116 0.008 0.96 0.0001 14.5 127.2(0.021) (0.0008) (5.03)

Pupae -0.232 0.017 0.99 0.0001 13.4 60.1(0.031) (0.0012) (1.37)

Egg to Adult

-0.59 0.004 0.98 0.0001 14.0 239.0(0.008) (0.0003) (6.27)

Scientific Notes 519

for release, that is when the mean soil temperature is at least 14°C, the threshold fordevelopment of B. affinis from egg to adult. In addition, the models allow developmen-tal events to be predicted under different temperature regimes. This forecastingmethod can be used to determine which B. affinis life stage may be most prevalent orhow many generations may have occurred at specific time intervals after release.

We acknowledge Dr. K. Steward and Mr. P. Madeira for supplying some of the tu-bers used in this study, and Dr. D. Gee for technical assistance in the laboratory. Wethank Drs. C. Barfield, R. O’Neil, and K. Yeargan for reviewing an earlier draft of thismanuscript. This research was supported with a grant from the California Depart-ment of Food and Agriculture. This article reports results of research only. Mention ofa proprietary product does not constitute an endorsement or a recommendation for itsuse by USDA.

SUMMARY

B. affinis successfully developed from egg to adult at 18, 21, 25, 28, 30, and 32°C,but could not complete development at 15 and 35°C. Simple linear thermal unit mod-els were constructed from the data. Completion of the egg stage required a mean of56.7 degree-days above 12.7°C; the larval stage, a mean of 127.2 degree-days above14.5°C; the pupal stage, a mean of 60.1 degree-days above 13.4°C; and from egg toadult, a mean of 239 degree-days above 14°C.

REFERENCES CITED

ARNOLD, C.Y. 1959. The determination and significance of the base temperature in alinear heat unit system. Proc. American Soc. Hort. Sci. 74:430-445.

ARNOLD, C.Y. 1960. Maximum-minimum temperatures as a basis for computing heatunits. Proc. American Soc. Hort. Sci. 76:682-692.

BALOCH, G.M., SANA-ULLAH, AND M.A. GHANI. 1980. Some promising insects for thebiological control of Hydrilla verticillata in Pakistan. Trop. Pest Manage. 26:194-200.

BENNETT, C.A., AND G.R. BUCKINGHAM. 1991. Laboratory biologies of Bagous affinisand B. laevigatus (Coleoptera: Curculionidae) attacking tubers of Hydrilla ver-ticillata (Hydrocharitaceae). Ann. Entomol. Soc. America 84: 420-428.

BUCKINGHAM, G.R. 1988. Reunion in Florida - hydrilla, a weevil, and a fly. Aquatics10: 19-25.

GODFREY, K.E., L.W. J. ANDERSON, S.D. PERRY, AND N. DECHORETZ. 1994. Overwin-tering and establishment potential of Bagous affinis (Coleoptera: Curculion-idae) on Hydrilla verticillata (Hydrocharitaceae) in northern California.Florida Entomol. 77:221-230.

NOAA. 1985. Climatography of the United States No. 20, climate summaries for se-lected sites, 1951-1980, California. USCOMM-NOAA. Asheville, NC 7/84/200.

SAS INSTITUTE, INC. 1982. SAS user’s guide: statistics, 1982, edition. Cary, NC.STEEL, R.G.D., AND J.H. TORRIE. 1960. Principles and procedures of statistics.

McGraw-Hill Book Company, Inc., New York, NY.WAGNER, T.L., HSIN - I WU, P.J.H. SHARPE, R.M. SCHOOLFIELD, AND R.N. COULSON.

1984. Modeling insect development rates: a literature review and application ofa biophysical model. Ann. Entomol. Soc. America 77:208-225.

520



DISPERSAL OF PLANT PESTS INTO THE VIRGIN ISLANDS

S

COTT

E. M

ILLER

Bishop Museum, Box 19,000-A,Honolulu, HI 96817

On 26 October 1990, Greg Mayer, Tina Kuklenski, and Scott Miller sampled in-vertebrates from a large shipment (an entire barge) of potted plants being unloadedat Guana Island, British Virgin Islands (BVI). Becker & Miller (1992) provide back-ground on Guana Island. The plants, including many specimens of several species ofpalms, were being imported from nurseries in southern Florida for landscaping. Theimporters had apparently met all BVI regulations and had checked in with govern-ment authorities in Tortola before the barge proceeded to Guana Island. The ship-ment was infested with large numbers of insects and snails, most of which have beenidentified as follows. A millipede, an isopod, and several beetle larvae were not iden-tified.

Cockroach (Blattodea: Blaberidae)

Pycnoscelus surinamensis

(Linnaeus), Surinam cockroachMealybug (Homoptera: Pseudococcidae)

Dysmicoccus brevipes

(Cockerell), pineapple mealybugAnts (Hymenoptera: Formicidae)

Brachymyrmex obscurior

Forel

Hypoponera opaciceps

(Mayr)

Odontomachus ruginodis

Wheeler

Paratrechina longicornis

(Latreille), crazy ant

Paratrechina pubens

(Forel)

Pheidole morerens

WheelerSnails (Mollusca)

Lamellaxis gracilis

(Hutton)

Polygyra

cf.

P. cereolus

(Muhlfeld)

Praticolella griseola

(Pfeiffer)

Succinea

cf.

S. luteola floridana

PilsbryAlthough some of these species are native to the Puerto Rican Bank, most are im-

migrant species that are now widespread in the Caribbean region, including southernFlorida (Godan 1983, Roth 1994). Most are known from the Puerto Rican Bank (Wol-cott 1950-1951). Several major agricultural pests are included, such as those withcommon names listed. The presence of this many invertebrates on this shipment in-dicates the ease of dispersal of agricultural pests.

Non-indigenous pests are a major problem for North American agriculture (Dowell& Krass 1992, Sailer 1978, 1983, U.S Congress 1993). In addition to being agricul-tural pests, non-indigenous insects and snails appear to be the primary cause of ex-tinction for native invertebrates on islands (e.g., Howarth 1990, Howarth & Ramsay1991). Vectors of human disease, such as

Aedes albopictus

(Skuse) (Asian tiger mos-quito), can also be spread by commerce (e.g., Francy et al. 1990, Mitchell et al. 1992).The recent spread of two giant African snails,

Achatina fulica

Bowditch and

Limico-laria aurora

(Jay), to Martinique is a stark example of the problem of continued pestdispersal (Mead & Palcy 1992).

Given the threat that non-indigenous insects and snails present to agriculture, hu-man health, and conservation management, and potential economic consequences ofsuch introductions, island governments should create and implement policies for the



, Vol. 77, No. 4 (1994).

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Scientific Notes

521

inspection of agricultural materials, including provisions for fumigation and quaran-tine as necessary.

Identifications were made by K. Emberton (Academy of Natural Sciences of Phil-adelphia, snails), D.R. Miller (Systematic Entomology Laboratory, U.S. Dept. of Agri-culture, mealybug), R.R. Snelling (Natural History Museum of Los Angeles County,ants), and J. Strazanac (Bishop Museum, cockroach). Voucher specimens were re-tained by specialists, except snails.

S

UMMARY

A large shipment of potted plants from Florida to the British Virgin Islands in-cluded live cockroaches (1 species), mealybugs (1 species), ants (6 species), and snails(4 species) on arrival at the destination, Guana Island. Several major agriculturalpests were included, emphasizing the need for more effective measures to preventcontinued spread of non-indigenous invertebrates.

R

EFERENCES

C

ITED

B

ECKER

, V.O.,

AND

S.E. M

ILLER

. 1992. The butterflies of Guana Island, British VirginIslands. Bull. Allyn Mus. 136: 1-9.

D

OWELL

, R.V.,

AND

C.J. K

RASS

. 1992. Exotic pests pose growing problem for Califor-nia. California Agr. 46(1): 6-8, 10-12.

F

RANCY

, D.B., N. K

ARABATSOS

, D.M. W

ESSON

, C.G. M

OORE

, J

R

., J.S. L

AZUICK

, M.L.N

IEBYLSKI

, T.F. T

SAI

,

AND

G.B. C

RAIG

, J

R

. 1990. A new arbovirus from

Aedes al-bopictus

, an Asian mosquito established in the United States. Science 250:1738-1740.

G

ODAN

, D. 1983. Pest slugs and snails: biology and control. Springer-Verlag, Berlin. x+ 445 pp.

H

OWARTH

, F.G. 1990. Hawaiian terrestrial arthropods: An overview. Bishop MuseumOcc. Pap. 30: 4-26.

H

OWARTH

, F.G.,

AND

G.W. R

AMSAY

. 1991. The conservation of island insects and theirhabitats, pp. 71-107

in

N.M. Collins and J.A. Thomas [eds.], The conservationof insects and their habitats. Academic Press, London.

M

EAD

, A.R.,

AND

L. P

ALCY

. 1992. Two giant African land snail species spread to Mar-tinique, French West Indies. Veliger 35: 74-77.

M

ITCHELL

, C.J., M.L. N

IEBYLSKI

, G.C. S

MITH

, N. K

ARABATSOS

, D. M

ARTIN

, J.-P.M

UTEBI

, G.B. C

RAIG

, J

R

.,

AND

M.J. M

AHLER

. 1992. Isolation of Eastern EquineEncaphalitis Virus from

Aedes albopictus

in Florida. Science 257: 526-527.R

OTH

, L.M. 1994. Cockroaches from Guana Island, British West Indies (Blattaria:Blattellidae: Blaberidae). Psyche 101: 45-52.

S

AILER

, R.I. 1978. Our immigrant insect fauna. Bull. Entomol. Soc. America 24: 3-11.S

AILER

, R.I. 1983. History of insect introductions, pp. 15-38

in

C.L. Wilson and C.L.Graham [eds.], Exotic plant pests and North American agriculture. AcademicPress, New York.

U

NITED

S

TATES

C

ONGRESS

, O

FFICE

OF

T

ECHNOLOGY

A

SSESSMENT

. 1993. Harmfulnon-indigenous species in the United States. U.S. Government Printing Office,Washington, D.C. (OTA-F-565). viii + 391 pp.

W

OLCOTT

, G.N. 1950-1951. The insects of Puerto Rico. J. Agr. Univ. Puerto Rico 32: 1-975.

522



BOOK REVIEW

C

RONIN

, H

ELENA

. 1991. The Ant and the Peacock. Cambridge University Press, Cam-bridge, xiv + 490 p. ISBN 0-521-45765-3. Paperback. $19.95.

The book is arranged into three parts with 16 chapters and has an extensive bib-liography, a list of cited correspondence between Charles Darwin and Alfred Wallace,and an index. The foreword was written by John Maynard Smith. The first part pro-vides a background for the remaining two, each of which tackles an evolutionary par-adox exemplified by the ant (altruism) and the peacock (sexual selection). How canself-sacrifice, especially reproductive self-sacrifice that places others at an advantage,possibly be passed on to subsequent generations? And how can flamboyant, burden-some structures be selected that seem disadvantageous to the bearer?

Part One, ‘Darwinism, its Rivals and its Renegades’, explores the views and con-troversies surrounding the theory of evolution through natural selection during andsince the time Darwin and Wallace published their respective versions in 1859. Divinedesign, directed evolution, and Lamarckism are contrasted with classical Darwinismand its tenet that evolution results from gradual change through a culling of “bad”traits, and that such natural selection acts on individuals rather than groups or spe-cies. As elsewhere in the book, the author explores historical changes in views thathave shaped modern Darwinism. The unit of natural selection has shifted from thegroup or individual to the gene and extended phenotype; the interpretation of pheno-type was broadened from the merely physical to the physical and behavioral; and theview that traits are purely adaptive or maladaptive gave way to recognition of strate-gic tradeoffs in costs and benefits. Although classical Darwinism overlooked the con-cepts of evolutionarily stable strategies and optimality, Cronin contends that overallit was still a good approximation of modern Darwinism.

In the six chapters of Part Two, ‘The Peacock’, Cronin applies the theory of sexualselection to explain the conundrum of why some traits seem counteradaptive, espe-cially in males. She discusses the virtues and failures of the handicap principle, whichargues that faults or hindrances should be exaggerated or simulated by an individualto demonstrate to potential mates that the individual thrives despite them and istherefore a good mate. Cronin also addresses the historical controversies overwhether sexual selection rather than natural selection can account for seeminglycounteradaptive traits, why mate choice is the mechanism behind sexual selection,and how, or if, Darwinian forces allowed it to evolve. Included, among others, are Wal-lace’s view that flamboyant male color is a physiological manifestation of higher en-ergy and vigor of males rather than a mate-selected phenomenon, Julian Huxley’sargument that male flamboyance is used in displays of threat rather than mate at-traction, and entomologist O.W. Richards’ insistence that male traits associated withmating are developed to stimulate a “passive”, but not choosey, female into mating.Throughout Part Two, Cronin outlines the many arguments, particularly those be-tween Darwin and Wallace, over whether the force driving the evolution of the pea-cock’s tail is sexual selection or natural selection. She ultimately contends that trade-offs and compromises are forms of adaptation, and that the trade-off between, for in-stance, reproductive success and predation in a flamboyant male is no different inprinciple from trade-offs between foraging and predation. Sexual selection, she con-cludes, is just one case of natural selection, and is not different after all.

Part Three, ‘The Ant’, is arranged into six chapters and deals with altruism. HereCronin describes the development of the idea of kin selection and explores the evolu-tion of theories on altruism, self-restraint, cooperation, and the evolution of sociality,including ethics and morality in humans. She continues to expound on the pitfalls of



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Book Review

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group selection, and argues that altruism is explainable only on the level of the gene.The last chapter is devoted to the disagreements surrounding the mechanism of spe-ciation, including the earlier notions ascribing an altruistic basis for hybrid sterilityand the separation of lineages, followed by a discussion of emphasis on geographic iso-lation versus natural selection as the most important force behind speciation.

This book does not generally bring to light profound new evolutionary thought. Itsvalue lies, rather, in its detailed interpretation of the reasons behind the transforma-tion of thought on two of the most fascinating topics in evolutionary theory, sexual se-lection and altruism. It presents a fine dissection of the prevailing views andpersonalities of a legion of evolutionary scientists and philosophers over the past 150years, as well as a clear summary of many aspects of evolutionary theory. Althoughthe topics may not be easy to grasp by the uninitiated, and the teasing apart of minu-tiae in some areas seems a bit excessive, Cronin’s witty and conversational tone none-theless coaxes the reader to new heights of understanding and avails the informationto biologists and non-biologists alike. For the entomologist, a satisfying peppering ofdiscussions on insects spices up a fare otherwise heavy on birds and mammals.

The book has a few minor shortcomings. It is occasionally redundant and in someplaces the reader is left puzzling about the relevance of a new paragraph until he orshe is well into it. The writing style, although entertaining and witty, is so idiomaticit may be nearly unintelligible to readers whose first language is not English. Thereare some minor omissions, such as no explanation for why Lamarckism was intu-itively acceptable to many people (page 44). An eagle is misidentified as an osprey inone of the illustrations (page 184), whereas in another illustration showing a seem-ingly normal male pelican, the caption leads the reader to expect that the bird issporting a huge bump on its bill (page 196).

Overall, however, the book is informative, provocative and well worth reading byanyone interested in evolution, the history of science, philosophy, or all of the above.

H

ANNAH

N

ADEL

Royal British Columbia MuseumVictoria, BC, Canada V8V 1X4

524



IN MEMORIAM

ALBERTO PERDOMO

Dr. Alberto Perdomo, Regional Specialist in Plant and Animal Health at the Inter-american Institute of Cooperation for Agriculture (IICA), died in January, 1994, at theage of 51. Alberto was born May 11, 1943, in Colon, Panama. He attended the ITESM,in Monterrey, Mexico, where he graduated as Engineer Agronomist in 1960-1964. Heobtained his Master of Science degree at the Instituto Tecnologico y de Estudios Su-periores de Monterrey, Mexico. He attended the University of Florida from 1971 to1974 where he obtained his Doctoral degree in Entomology. He was Director of Plantand Animal Health at IICA with responsibility over Mexico, Central America, Pan-ama and the Dominican Republic. Alberto also worked for the International Organi-zation of Atomic Energy as an expert in the project MoscaMed in Lima, Peru and inGuatemala from 1971 through 1987. He was Director of Agricultural Production atthe Ministry of Agriculture in Panama from 1981 to 1982 and taught at the Univer-sidad de Panama from 1974 to 1977.

Dr. Perdomo was known throughout Florida, especially among Fruit Fly special-ists. He had kindly offered to help with the organization of the 1995 Caribbean Con-ference of Entomology in San Jose, Costa Rica.

His good-natured friendliness has been, and will be missed, but not forgotten. Heis survived by his wife, Rosa, a son, Alberto, his daughter, Malena and a host offriends.

J

ORGE

E. P

ENA

R.M. B

ARANOWSKI



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