Eng5

Jfuas No.1 June 2013

53

Ovipositon sites of Zonocerus variegates (L.) along the

major seasonal water courses(Wadies) in Darfur Region.1-Ibrahim Abdel/Rahman Ibrahim Abdel/Fattah, Faculty of Enverionmental

Sciences and Natural Resourses, Department of Plant Protection, University of Al

Fashir

2.Elwasila Guddoura Mohamed, Faculty of Agriculture, Department of Crop

Protection, University of Khartoum, Sudan.

المزركش الجراد بيض وضع أماكنبدارفورضفافعلى الموسمية ا!ودية

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Abstract

This study was carried out in Darfur Region during the period (1999 -

2002), and its objective was to identify the insect pest, it is life cycle,

ecology and behavior. Zonocerus species currently existing in

Western Darfur is the variegated grasshopper, Zonocerus

variegatus(L.),with two local names, Maradona and Bo. The species

has got only one generation per year, both under field and laboratory

conditions. But it splits into two distinctive populations, the dry and

wet season populations due to the effects of ecological factors e.g. soil

moisture and temperatures. The dry season population has large

density and causes considerable damage to the summer crops. The two

populations overlap and interbreed with each other by the end of the

rainy season. Results indicated that this pest has infiltrated into

Western Darfur through seasonal water courses (wadies) which run

across the borders with Chad and Republic of Central Africa and

recorded as a pest in season (1994) at El Gineina. The pest has a close

ecological relationship with the bush Ipomoea fistulosa, which

provides the grasshopper with oviposition sites under its shade,

hiding, resting places and probably secondary plant metabolites to


55

develop its defense mechanism against natural enemies. Results

indicated that the egg pods density in one square foot is about

30.66+14.31, each with 21-96 eggs/pod.Keywords: Bo- locust / grasshopper, Zonocerus variegates, Wadi, Gerf soil, seasonality

1. Introduction

There are several grasshopper species capable of inflecting

considerable damages on different crops on many occasions in the

Sudan. As the grasshoppers have the capacity to live in a wide range

of habitats with great variations in the details of their biology and

behavior, the problem of these insect pests is becoming a chronic one

in the Western Sudan particularly in Darfur Region.

Indigenous grasshoppers, have for long being a real threat to the

Qoz and Wadi- cultivators, where significant losses usually occur on

millet, sorghum and vegetables. Thus, the food situation is becoming

unsecured in the marginal areas of the western states of the Sudan,

where grain production is risky.

It is well known that, unusual weather changes and land use are

the main factors responsible for encouraging grasshoppers problems.

However, the Central Plant Protection Directorate (P.P.D) has for long

keeping a close guard, through its effective control measures against

quite a number of pests including the grasshoppers. Though the

implementation of the new privatization approaches on pest control

strategies have deprived the farmers from the essential (P.P.D)

support. The new policies, states that, minor pests including

grasshoppers are becoming farmers responsibility.


56

Under the poor economic situation, most of the farmers are

financially incapable to purchase pesticides and spray equipment to

combat the grasshoppers. Accordingly their reproductive potential has

grown unchecked above economic injury levels. During seasons, 1995

and 1998, North Darfur witnessed local outbreaks of grasshoppers

which were restricted to certain habitats in El Fashir, Kebkabyia and

Umkadada provinces. In Eliet Gar Elnabi (Umkadadda), a total area of

5000 feddans grown by groundnuts, millet and other field crops were

completely destroyed by the significant populations of (11)

grasshoppers species acted as a group (P.P.D,1995). The same is true

in Kebkabyia, when the hole Jebel Ci area, 80 Kms in length from

Kagrio in south up to Milla in north was devastated by (21)

grasshoppers species act as a group, (Oxfam, 1999).

Though some injurious species like Oedaleus senegalensis

(Kra.),Aiolopus simulatrix (Walk.) etc.. Each can by own cause severe

crop damage.

Food situation might become worse since a new grasshopper,

Zonocerus variegatus (L.) appeared in western Sudan. Of all identified

locusts and grasshoppers, Zonocerus variegates (L.) was regarded as

an important species together with some other injurious grasshoppers

ie. Hieroglyphus daganesis (Kra.), Oedaleus senegalensis,(Kra.),

Kraussaria angulifera (Kra.), Aiolopus simulatrix (Walk.) and

Anacridium melanorohodon (Walk.) (Popov, 1989).

Mohammadein (1996) stated the first appearance of Z.

variegates (L.) in an outbreak in Western Darfur State where an area


57

of about 75190 hectare was infested by this serious grasshopper. Since

that time the pest was continuously endangering the whole agricultural

sector in Darfur Region and migrating inward to invade new areas. Z.

variegates (L.) is strictly polyphagous grasshoppers with a wide range

of food acceptance. It does seem that the species alone can cause a

massive loss on different crops grown along the wadies. Although this

grasshopper has reached a pest status recently, yet it's significant

damaging levels on the economically important cereal and

horticultural crops ranked it as one of the most serious insect pests

currently existing in the whole region. Because, Z. variegates has been

recorded a pest recently in the Sudan therefore, cumulative knowledge

about its biology, ecology behavior control etc, is almost unknown in

the Sudan.

Hence, the study is aiming to provide knowledge on various

subjects conditions related to the understanding of the grasshopper

under the local condition through conducting comprehensive field and

laboratory investigations. Expected findings are required to help in

solving the current problems under field condition and to build a base

for future studies.

2. MATERIALS AND METHODS

The study was carried out in the greater Darfur region with

special emphasis to the major seasonal water courses (wadies),Kaja,

Barei, Azum , Salih and their tributaries of the western, northern and

southern Darfur states Fig(1).


58

The course of the study took three successive seasons, 1999,

2000, 2001 and 2002, during which various ecological, biological etc.

aspects related to the newly infiltrated insect pest, the variegated

grasshopper, Zonocerus variegatus(L) were investigated, both under

field and laboratory conditions. During the course of work biological

studies were carried out through using an effective qualitative and

quantitative methods mainly observations, identification of specimens

, photographing, diagrams and classification of the different instars

according to age and population types by random sampling technique

(for encouraging information capacity building of the subject under

test, surveys and control facilities of the Plant Protection Department

(P.P. D.) ElGineina, Kebkabyia, and Zalingei were put in use during

the entire course of field studies). Meanwhile fresh samples of

different stages of Zonocerus and population types were regularly

supplied by P.P.D. working teams for further investigations and

making comparisons. Accordingly, infested areas out of reach became

quite accessible to cover as wider areas as possible

Studies were aimed firstly to identify the common Zonocerus species

currently exiting in Darfur States.

Adults were randomly collected from host plants using

sweeping and hand picking during low temperatures i.e early

mornings and late evenings. The specimens were indentified using the

key of the common species of the sahelian grasshoppers (1987), as

well as using the photo plates and descriptions presented in the texts,

guides and handbooks, developed by Drish 1965, Mestre1988,


59

locoq1988, and Steedman1990. Comprehensive studies covered, the

migration of the species into the western State , it's host range and

nature of damages, biological cycle and the phenomenon of

population dynamics and oviposition sites , natural enemies etc.

information gathered were recorded accordingly.


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3. Results

3.1 Oviposition site description

58% of the total searched bushes on the two breeding habitats

(wadi slopes+ water collecting sites) were found containing egg pods.

Also 62.07 % of the discovered oviposition sites were found along the

slopes of the wadies, whereas 39.93% were found around water

collecting sites closer to the main courses.

With respect to the type of pushes selected for egg laying,82.76%

of the discovered oviposition sites were found under Ipomoea

fistulosa growing alone , whereas 17.24% of the discovered egg fields

were found under I. fitulosa growing together with other plants

species i.e. wild trees ,citrus of the wadi banks, table (1).

Oviposition sites were not detected under I.fistulosa growing in

habitats that lack essential ecological requirements responsible for

encouraging laying such as suitable soils enough moisture etc On the

other hand Oviposition sites were also not detected under some

I.fistulosa growing adjacent to others containing eggs although

Oviposition inductive factors were quite abundant during the breeding

season .

During the breeding activities, adults become concentrated in

habitats possessing specific egg laying requirements. These habitats

were examined firstly by a limited number of females prone to laying

where then many other individuals from the neighboring bushes

become attracted partly by the effects of the gergrization pheromones


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evolved by the initial population and partly by the bright yellow

coloration.

With regard to the type of habitats selected for breeding, it was

found difficult to detect oviposition sites around water collecting sites,

because egg laying holes were concealed by distortions made on soil

surface by the movements of the visiting birds and animals.

Such oviposition sites can only be discovered after removing the

upper most soil layer.

However, when the top soil layer was removed carefully with a

knife, egg holes became quite visible with a reddish foamy substance

topping the egg pods. In contrast it was found easy to detect

oviposition sites along the wadi slopes (gerf soils) the most attractive

habitats to Z.variegatus(L.)

As wadi extended flood plains were confined to certain areas ,

large oviposition sites have been discovered under I,fistulosa during

seasons, 2002-2001, at the lower stream zone of wadi – salih

(klimbasanga) and kayang flood plains of Wadi Bari , Saraf Umrra,

Abutinnayia.F ig.(2)

The exact egg laying sites have been found in the mid zones of the

wadi slopes (gerf soils), approximately 30 cm above the wadi base or

foot, where I,fistulosa shade falls onto. However, in certain areas

I,fistulosa bushes shade was supported by some more shade of the

largest citrus (mango, guava) and other wild trees(indigofera

sp.Acacia nilotica etc.) growing adjacent to I,fistulosa on the wadi

banks). An oviposition site can extend laterally along the wadi slope


63

where the shade extend provided that, and accordingly the breeding

population is increased if other favorable factors are still prevailing. In

contrast the width of an oviposition site was restricted vertically up

and downward across the slope according to the levels of soil

moisture. There exit at the wadi base or foot a permanent, but broken

or discontinuing water ponds that apparently appear in the half way of

the running course all the year round drop .

Table(1) : The oviposition sites of Zonocerus variegatus(L.) discovered

under different plant species growing in different breeding habitats

along wadi Kaja, EL Gineina province, season 2002

Type of

breeding

habitats

No. of

sample

Plant species Total

oviposition

sites

discovered

%discovered

oviposition

sites

I.fistulosa I.fistulosa

other

plants

Wadi-

slopes(Gerf-

soil)

25 15 3 18 62.07%

Water

collecting

sites

25 9 2 11 37.93%

Cultivated

areas

No sample

taken

Total 50 24 5 29

% Total 82.76 17.24 58%

��

Measurements of oviposition site revealed that, the egg laying of

Z.variegatus(L.) hasn't got a fixed size or a shape but , it varies from


64

site to site, and ranges between (L 2.8-12x W 1-2m) with an average

mean of 8.31±6.06 square meter,

Table (2): Results of soil analysis used by Zonocerus variegates for egg

laying:

s.p

pH

EC

e

Na

g/L K ca

Mg

CO

3

HC

O3

CI

sand

Silt

Clay

Tex

ture

45 7.8 55 3.6 0.3 1.0 4 0.5 2.5 1.5 54 24 22Sandyclay loam

��

Soil is sandy clay loam. It is characterized by high water saturation % (S. P).

PH in neutral none salinesoils. Moderate cations and anions. Non

compacted soils or fragiable soils easy to be fragmented.

Table (3): the oviposition site investigation of Zonocerus variegatus(L.)

carried out at wadi Kja, season 2002.Description No of

samples

taken

Range Average

The size of oviposition site . 10 L2.8-12x

W 1-2m

8.31±6.06m

Number of egg per pod 30 21-96 eggs 53.2±19 eggs/pod

Length of an egg laying hole 27 9-13 cm 11.22±1.16cm

Height of an egg pod 28 2.8-5cm 3.87±0.88 cm

Foamy secretion height 27 3-6 cm 4.3±0.76 cm

Number of egg pods in one foot

square

50 2-59 egg

pods

30.66±14.31 egg

pods/one foot

square.

The density of egg pods in one foot square.The density of egg pods of

Z.variegatus(L.) ranges between 2-29 egg pods/foot square with an

average mean of 30.66±14.31 egg pods per one foot square.An egg

laying hole, an egg pod, egg per pod and foamy substances of

Z.variegatus(L.)The depth of an egg laying hole of Z.variegatus (L.),

ranges between 9-13 cm with an average mean of 11.22±1.16 cm. the

hole is prepared to accommodate two component, the egg pod and the


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foamy substances fig(2) . An egg pod is made of earth while a female

undergoing it's laying process during the breeding season. It is located

at the lower part of the egg laying hole its height ranges between 2.8-

5 cm, with an average mean of 3.87±0.88 cm. Each egg pod contains,

21-96 eggs with an average mean 53.2±19 eggs. Eggs were laid in V

shape with instar emergency exits on top.

The upper most soil layer (3-6 cm) where foamy substances were

secreted was found dry. In contrast the lower layers where egg pods

were inserted retained considerable amount of soil moisture. An egg

pod prevents loss of moisture from the eggs and it was topped by

foamy substances up to the soil surface.

The newly secreted foamy substances have the color white, then turns

into reddish by time.

Its height ranges between 3- 6 cm with an average mean 4.30 ± 0.76 cm.

Parasites, predators and pathogens

Large numbers of egg pods of Z.variegates (L) were found infected by

pathological agents at the northern slopes of wadi Kaja 5 Kms

approximately south of EL Gineina city. Results of the test revealed

that, the causal agents are fungal pathogens belonged to the family

zoopagaceae, according to the Botany Department , Faculty of

Science, University of Khartoum .

3.4 Oviposition soils analysis

Soil samples (containing Z. variegates eggs) were analyzed at the

laboratory of the Department of Land Use and Desertification Control

(Khartoum).Results of the analysis is presented in Table (2).


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1. Discussions

Results of this study indicated that, the wadi slopes and the water

collecting sites are the main breeding habitats, (58%) of the searched

bushes found containing egg fields, with 62.07% of the total sites

discovered along the slope. This would, however proves that the wadi

slopes are the best habitats for laying eggs along which favorable

ecological conditions prevail, such as suitable soils, food sources,

shelters etc. with the fact that 82.76% of the discovered oviposition

sites found under I.fistulosa would however, ensure that, there exist

along the wadies a closest relationship (but not exclusive) between Z.

variegatus (L.) and the bush I.fistlosa probably for satisfying a variety

of options, but unlikely to be important as a food plant, although the

pest feeds upon and that the plant is not consumed for it's food value .

Results showed that the plant is not only selected for oviposition

purposes but also for hiding and a resting place.

However the plant may also be used for getting secondary metabolite

I.e. PAs which they later employ for their defense against predators

and parasites. Abdel Hadi (1987) identified the alkaloid ergometrine

from I.fistulosa which is probably the compound that causes Z

.variegatus (L.) to be attracted. The pharmacophagous relationship

between Z. variegatus (L.) and the plant C.odorata was intensively

studied by Bopper (1991), Bopper and Fischer (1994).Modder (1988)

and Idown and Akinsete (2000). In addition to C. odorata, Z.

variegatus (L.) has a wide host range including several additional PAs


67

plants such as Heliotropium (Boraginaceae) as well as Emilia and

Ageratum (Asteraceae).

The grasshopper is attracted to pass during their entire life

independent of the amount of past already ingested (Bopper and

Fischer, 1994). Results indicated that, the closest relationship of the

pest with I.fistulosa would ensure that, Z. variegatus(L.) has got many

PAs alternative plants in nature which can make use of in the absence

of its classical host plant, C. odorata.

In this sense, the need for a comprehensive work of PA plant sources

including, I. fistulosa is important in the view that, the survival

strategies and seasonal occurrence of this harmful insect is

ecologically geared with noxious plant species usually neglected.

The absence of egg fields from I. fistulosa lacking essential

oviposition requirements would ensure that the pest is purposely

attracted to the bush for getting certain requirements essential for

survival.

In contrast the absence of oviposition sites under some I. fistulosa,

although encourageable factors for breeding are quite abundant, is

attributed to the dynamic trends of adult populations of the pest which

is behaviorally controlled by the gregarisation pheromones during the

breeding activities.

The detection of oviposition sites can be made by searching areas

most likely to contain eggs specially under I. fistulosa growing at the

wadi slopes (Gerf soils), by digging with a knife. Also the remains of

the dead bodies can be making use of as good indicators. However,


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some difficulties may be experienced when seeking for oviposition

sites around water collecting sites which require digging or removing

upper soil layer. Results confirm that the bulk of oviposition sites of

the pest occur at the wadi slopes which gives early rise to the first dry

season hatchlings. Oviposition sites appear in the form of colonies, but

extend along the slope. This finding confirms the work done by Popov

(1978).

The discontinuing water ponds along the wadies specially at the half

ways provides a permanent moisture sources which keep eggs remain

viable during the dry conditions.

In this study, the size of an egg field measured 8.31±6.06m², although

pans Manual (1986) reported that egg laying sites are unlikely to be

more than 5m².

However , results showed that egg laying sites haven't got specific size

nor a shape, but their vary with respect to the size of the effective

breeding females, they fertility levels suitability of soil and

availability of soil moisture, space availability, the shade offered by

the bush plant etc.

The present study indicated that, the density of Z. variegatus (L.) egg

pods in one foot square is about 30.66±14.31 at the wadi slope (Gerf

soils).

When converted into m², it will be 340.63 egg pods (28 dozens) which

are considered a high density. This finding agrees with Pastre et al.

(1989) who reported that, the laying is closely grouped, and the

density of the egg pods of the variegated grasshopper is sometimes


69

very high (several dozen per square meter). The high egg pod density

per unit area will provide a rough measure forecasting the size of the

expected populations and their menace accordingly. It would also help

in planning for selecting an appropriate control measure to destroy

eggs before hatching specially when using infections fungal

pathogens. In this regard the fungal pathogen found attacking the eggs

is promising.

The study indicated that, the depth of an egg hole is about 11.22±1.16

cm which differ from pans Manual (1986) who reported 15 cm. These

differences may be due to differences in soil types and their condition

under which eggs were deposited.

The upper most soil layer (3-6cm) is dry. In contrast the lower layers

where eggs are imbedded contain considerable amount of moisture

which enabled eggs in diapauses remain viable during the dry

conditions. This type of survival strategy is referred to as survival

strategy in the egg stage which is very common on many grasshopper

species (Popov, 1989).

The foamy substances secreted by the females during the laying

process act as a protective cover topping the hole, and a passage or an

exit through which the newly emerged instars can get outside the pod

hole ventilation can also be made accessible through this substances.

It is possible to suggest that these foamy substances which may

contain secondary plant metabolites Idowu and Akinsete (2000), in

this study, probably, from I. fistulosa might temporary afford some

sort of the protection to the incubated eggs against the natural enemies


70

at least during the laying period. This suggestion agrees with Bopper

(1991) who reported that, the secondary plant compounds obtained

from C. odorata are stored and chemically protect the grasshopper and

practically their diapausing eggs from predators i.e.(Larvae of

Mylabris Beetles or Parasitoids).

However, repellency may be lost by time due to the effects of the

physical factors and eggs may become liable to attack by egg parasites

and predators. Modder (1988) reported that 40% of dry season eggs

are predated suggesting that stored PAs give no protection.

References

Adel-Hadi, A. A. (1987), Pharmacological and phytochemical investigation

of Ipomea carnea subs. Fistulosa. Ph.D. Thesis, University of

Khartoum,Sudan.

Boppre, M. (1991). A non-nutritional relationship of Zonocerus

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