AVANCES EN ENTO MOLOGiA IsfRlcA, 1995, págs. 179-188

Phytophagous insects associated with endemic, macaroneSlan, and exotic plants in the Azores

L. SIL 'A J. TAVARES

Abstract: A survey of Myrica faya Aiton (Myricaceae) natural enemies, was per­form.ed fra m. 1991 to 1993, in order to f1nd potential biocontrol agents for that plant, an ibero-macarones ian endemic, considered as a noxious weed in Hawaii. Samples were collected weekly at two sites in São Miguel, and complementary at São Jorge, Faial, Pico and Terceira islands (Azores). Since 1992, the survey was extended to include phytophagous insects associared wi th the other dominant trees at l\1yrica faya stands : Erica scoparia ssp . azorica (Hochstetrer) (Ericaceae) an endemic, and Pittosporum unduLatum Ventenat (Pinosporaceae) an exo tic planr. Only 20 species of phyrophagous inseCLs were found: two H erero ptera, ten Homoprera, one Thysa­noptera, two Coleoptcra and five Lepidoptera. M. foya and E. scoparia ssp. azorica support the life-cycle of four endemic insecrs. P. unduLatum is an occasional shelter for so me insects. A correspondence analys is c1early separated the rhree plants, on the basis of rheir associared phytophagous insects.

Insectos fitófagos associados a plantas endémicas, macaronésicas e exóú cas, nos Açores.

Resu mo: Emre 1991 e 1992, realizou-se a prospecção dos inimigos na rurais de Myrica fo)'a Aiton (Myricaceae), um endemismo ibero-macaronésico, considerado como uma infestante nociva, no Hawaii. A amostragem foi semanal, em dois locais da ilha de São Miguel.. Efectuaram-se amostras complementares nas ilhas de São Jorge, Faial, Pico e Terce ira (Açores). A partir de 1992, es tudatam-se igualmente os insectos firófagos associados a duas plantas abundantes nos biótopos de M. foya: Erica scoparia ssp. azorica (Hochstetrer) (Ericaceae) um endemismo, e Pittosporum unduúttum Ventenarr (P ittosporaceae) uma exó tica. Encontraram-se 20 espécies de insectos fitófagos: dois Hereroptera, dez Homoptera, um Thysanoprera, dois Coleop tera, e cinco Lepidoprera. M. foya e E. scoparia ssp. azorica suportam o ciclo de vida de quarro insectos endémicos. P unduLatum funciona como abrigo ocasional para alguns insectos. Uma análise de correspondências separa as três plantas, com base nos insectos firófagos associados a cada uma.

INTRODUCTION

Myrica faya Aiton (Myricaceae) is a small tree or shrub that is considered an ibero-macaronesian endemic (QUEIRÓS, 1987). T he pIant was inrroduced to

180 L. Silva y J Tavares

Hawaii by the end of the last scentury, and in the 1950's it was already considered a noxious weed, invad ing pastures, rangelands and the natu ral ecosystems ofHawaii (YAMAYOSHY, 1954; VITOUSEK et aI., 1987). On the other hand, in its na tural habitat, namely in the Azores islands, M. foya disrribution is decreasing, as a consequence of human activities and after the inuoduction of Pittosporum undulatum Vemenat (Pitrosporaceae) (DROUET, 1866; SJOGREN, 1984; QUEIROS, 1987).

A survey fo r the natural enemies of the piant was initiated in order to nnd potemial, biocontrol agents (KAAuss, 1964; H ODGES & GARDNER, 1985; GARDNER et aI. 1988; MARKlN, 1990; MARK:rN et ai., in press). ln 1991, a survey was started in the Azores, but since Erica scoparia ssp. azorica (Hochsterrer) ( ri caceae), an endemic, and P undulatum, were also dominating the vegetation in that area, we decided to extend our sampling program to those planrs.

ln the present work the phytophagous insects associated with each of those plants are compared , and those foundin Myrica foya are evaluated as potemial biological control agenrs. Consequences of a further spread of the exoric pIam on the community of phytophagous insects are discussed.

METHODS

Sampling was performed weekly, at two places at São Miguel lsland (Azores): Lombadas (55 0 m) and Pico das Camarinhas (150 m). C omplemen­tary, sampIes were taken at orher iocarions in São M iguel island and ar the islands of São Jorge, Faial, Pico and Terceira.

Insects were collected by:

bearing in the foliage, and collecring the falling insects with an entomological ner (bearing in 100 branches, per plant species); cutting terminal shoots with flower, fruit or leaf damage (30 shoors per

piam species).

lnsects were moumed or preserved in 75% ethanol, and sem for idemin cation. Species were sorted in categories, depending on their total abundance alI arround rhe year, namely: O) absent; 1) log(total number) ~1; 2) log(total number) ~ 2; and 3) log(toral number) >2.

Where possible, insect degree of host specincity was analysed, or checked in the literature.

A correspondence analysis was performed for the three plants at the two si­tes in São M iguel, using the abundances of the various species as variables.

181 Phytophagous insects associated with endemic, macaronesian ..

RESULTS

O nly twenty species of phytophagous insects were found (Table 1): two Heteroptera, ten H omoptera (one endemic), one T hysanoptera, two Coleoptera and five Lepidoptera (three endemic).

Table I

Phytophagous insects associated with an exotic (Pittosporum undulatum), a macaronesian (Myrica foya) and an endemic pJant (Erica scoparia ssp. azorica) at twO sites in São Miguel Island, Azores:

Lombadas (550 m) - L; and Pico das Camari nhas (150 ro) - C. Data was coUected from O ctobcr 1992 until Ocrober 1993. Complementary, sampling was performed

at other sites at São Miguel, São Jorge, Faial, Pico and T erceira Islands. *Breeding populat ion

H ost Piam

Erica scoparia Myrica Pittosporum ssp. azo rica foya undulatum

Insect L c L c L c

HETEROPTERA Miridae

Orthops sp. Lygaeidae

KLeydoce ris truncatuLus (Walker) 2* 2 2 2 HOMOPTERA

Cercopidae Philaenus spumarius Linnaeus

C ixiidae Cixius insularis Lindberg 2 2

F1aridae Cyphopterum sp.

Apbididae Aphis gossypii Glover o o Pico* o o

PsylJidae Strophingia harteni Hodkinson 1* 2* o O O O Trioza alacris Flor l

Coccidae Ceroplastes sinensis (Dei Guercio) O O Lagoa* O O

Diaspididae ChrysomphaLus sp. 2 2 O O

Margarodidae lcerya purchasy (Maskell) O O

Pseudococcidae Pseudococcus sp. O O Lagoa, Terceira* O O

182 L. Silva yj. Tavam

H osr Planr

Erica scoparia Myrica Pittosporum ssp. azo rica faya undufatttm

Insect L C L C L C

THYSANO PTERA T hrip idae

Hefiothrips haemorroicfalis Bouche 2* O O COLEOPTERA

Niridulidae Afeligethes aeneus (Fabricius) 2 O O

Anasp idae Anaspis proteus Wollasron

LEPID OPTERA Yponomeurid ae

Argyresthia atlanticefa Rebel 3* 3* 3* 3' O O Gracillariidae

Calaptilia atlranfiaca (Wollasron) O O O 2 O O Geomerridae

AseatiJ flrtunata azarica Pinker 2* 3* 3* 3* 1 G"ymnoseelis rufifasciata (Hawonh) O O Lagoa* O O Cyelapha ra azaremis (Prour) 3* 3* O O O O

Spcc:ic-s wcre sorted in c:I [t"gorics. dependi ng of rheir annual abu ndanc...e, n3nldy: O) abscnr; I} log(tmal number) 5. 1; 2) log(lOral

nu mbcr) S 2; and 3) lo)«toral l1umbcr) > 2.

Erica scoparia SSp. azorica supports the complete life-cycle of Kleydoceris truncatulus (Walker) (H eteIOptera, Lygaeidae), Strophingia harteni H odkinson (Homo ptera, Psyl lidae), Argyresthia atlanticella Rebel (Lepidoptera, Ypono­meuridae), Ascotis fortunata azorica Pinker (Lepidoptera, Geometridae) and CjJclophora azorensis (PIOur) (Lepidoptera, Geometridae). Myrica foya supports the life-cycles of Ceroplastes sinensis (DeI G uercio) (Homoptera, Coccidae), Heliothrips haemorroidalis Bouche (Thysanoptera, Thripidae), Argyresthia atlan­ticella, Caloptilia aurantiaca (Wollaston) (Lepidoptera, G racillariidae) and Ascotis fortunata azorica, but the first (wo insects as well as Gymnoscelis rufifos­ciata (H aworth) (Lepidoptera, Geometridae) , are rarely found on thar plant. Active populations of Chrysomphalus sp. (H omoptera, Diaspididae) and Pseudo­coccus sp. (Homoptera, Pseudococcidae) were also foun d on M. foya. T he other insects were pIObably only using Myrica and Erica as shelter and not as a pri­mary host.

As regards P undulatum, we have found very reduced feeding damage cau­sed by insects, and we suspect that this piam, in the Azores lslands, is only an occasional shelter for some insect species.

-1

183 Phytophagous insects associated with endemic, macaronesian..

i a LI

/\Ii

ThPI G2

-1

Figure 1. Correspondence ana.lysis. Simwtaneous proj eclÍon of the variables (insects abundan­ce) and obj ects (differem plants at two differem sites). Data based on the abundances of diffe rem species oE phytophagous insects, over three pIam species at tWO sires in São Miguel Island, Azares. Pc. Pittosporum unduLatum at Pico das Camarinhas PL. Pittosporum undu/atum at Lombadas EC. Eriea seoparia ssp. azo rica at Pico das Camarinhas EL. Eriea seoparia ssp. azorica at Lombadas MC. M)'riea foya at Pico das Camarinhas ML. Myriea foya at Lombadas Li - Lidgaeidae, Ci - Cixiidae, Ps - Psyllidae, Ma - Margarodidae, Di - Diaspididae, Ni -Nitidulidae, Th - Thrypidae, Gl & G2 - G eometridae, Yp - Yponomeutidae, Gc ­G racillari idae.

A correspondence analysis on rhe data collecred ar two sires in São M iguel (Figure 1), clearly separared the rhree planrs, on the basis of rheir associated phy­tophagous insecrs. The first axis, separares M. faya from E. scoparia ssp. azo rica, and the second separates rhese two planrs from P undulatum. T he main diffe­rence bctween M . faya and E. scoparia ssp. azo rica is rheir association with Caloptilia aurantiaca and Cyclophora azorensis, respectively.

DISCUSSION

Ascotis fortunata azo rica, an endemic defoliator, is a polyphagous species (SILVÂ, 1992), feeding on M. faya and E. scoparia ssp. azo rica, as well as on orher pianr species, namely: Myrsine africana L. (Myrsinaceae), Viburnum tim.is spp. subcordatum (Trel.) Padre Silva (Caprifoiiaceae) and Ligustrum henryi Hemsley (O leaceae). First insrars cause only light scarifi carion on rhe leaves, but lasr instars originare large feeding damage during summer monms. Larvae are also abundanr over E. scoparia ssp. azo rica.

Argyresthia atlanticella is a flower miner, feeding of M. faya mal e flowers

184 L. Silva y j. Tavares

(G RDNER et ai., 1988), and green fruits, but aIso of E. scoparia ssp. azorica and Vaccinium cyLindraceum Smathers in Rees (Ericaceae) flowers and leaves. Starvation tests showed that this insect is polyphagous (SILVA et aI., in prep.). ln multiple choice oviposition tests, the insect prefered E. scoparia ssp. azo rica, whi­le M. faya, Cafluna vulgaris (L.) (Ericaceae) and Vaccinium cyLindraceum, were not so frequently se/ec ted as oviposit ion sites, and Juniperus brevifoLia (Seubert) An oine (Cupressaceae), Pofygonum capitatum D. Don (Polygonaceae) and Myrsine africana were only rarely selected (SILVA, et aI., in prep.). Firs t instar lar­vae developed tO the ad ult stage feeding of M. faya flowers and green fruits, E. scoparia ssp. azorica flowers and leaves, V cylindraceum flowers and leaves, and P capitatum flowers . First instars search for a flower or a leaf tO mi ne. Last ins tars feed from the oLltside. Larvae are found ali arround the year ove r Erica scoparia ssp. azo rica, but also during Myrica faya, Vaccinium cy/indraceum and CaLLuna vulgaris flowering periods.

Cycfophora azorensis brst instar larvae were tested (unpublished data) usi ng Erica scoparia spp. azorica, Cafluna vuLgaris, Vaccinium cyLindraceum, Myrica faya, Myrsine africana, Viburnum tinus ssp. subcordatum, Pittosporum unduLatum, Laurus azorica (Seub.) Franco (Lauraceae), and I1ex perado sp. azorica (Loes.) Tutin (Aquifoliaceae). Larvae only survived and dcveloped on Erica scoparia ssp. azorica. he o cher tested planrs did not allowed survivaJ beyond three days, and larvae never reached second instar. O nly Erica scoparia spp. azorica (Ericaceae) was a suitable h osc, supporting the !ife cycle of the insecto Larvae feed on flovver buds and leaves, and are abundam ali arround the year. ln oviposition tests, Erica was clearly prefered tO Myrica, with a tOtal of 279 and 13 eggs, respecti­velly.

CaloptiLia aurantiaca is a leaf-miner that was released in H awaii (MARK.IN, 1990). Ir was brst erroneously identibed as PhyLLonorycter myricae Deschka (Lepidoptera, Gracillariidae). T hi insect was found associated with Myrica faya and Hypericum jofiosum Airon (Hypericaceae) . First instars mine M. faya leaves, b ut sim ilar mines were found on Hypericum joLiosum in Terceira and São M iguel Island . Last instar larvae leave the mine and roll the tip of the leaf, creating a chamber where they pupate. Two spe ies are known for the Azares (CARVALHO, 1982), CaLoptiLia aurantiacaand Caloptifia bistrigeLLa (Rebel). CaLoptilia schinel/a Walsingham from Madeira (AGUIAR, 1993) is a polyphagous insect that also fe­eds 011 Myrica faya.

Gymnoscelis rufifasciata feeds on Cynara carduncuLus L. (Asteraceae) flowers and is considered as a p st in Egypt (SADDIK & EL-MINIAWI, 1978). ln the Azores th is species was found on Laurus azo rica and Myrica faya flowers. T his species was considered as a pest of various crops (HARAKLY & ASSEM, 1978).

Kleidocerys truncatuLus was collected at Lombadas and Pico das Camarinhas, specially in Erica scoparia ssp. azo rica. Ir is largely established in the Eastern

185 Phytophagous imects associated with endemic, macaronesian ..

Palearctic region . ln England it is associated wíeh Eriea sp.. It probably feeds on seeds or mature fruits. ln the Azores many specímens were found ín Eriea seopa­ria ssp azoriea, but also in Juniperus brevifolia and Pittosporum undulatum. Kleidoeerys resedae Pam. in France (VILLIERS, 1977) and Kleidoeerys truneatulus erieae Horvarth in Madeira are found ín Eriea spp. (AGUIAR, 1993) . T his insect is noe speciflc to Myriea faya.

Cixius insularis Lindberg (Homopeera, C ixiidae) an endemic, was found sin­ce March mainly in spring and sum mer, bu( also in Eriea seoparia ssp. azoriea and Juniperus brevifolia, including where no M. faya exists (C aldeira, Faial). Cixiidae nymphes are found in soil where ehey feed on the roots of the host. Adults feed on various host specíes. Cixius nervosus L. and C. pilosus 0 1. are com­mon in France where they have several hosts (VI LLIERS, 1977). AGUIAR (1993) has found Cyxius vertiealis Noualhier in M. faya on M adeira.

T he remaining species (Table 1) are known to be polyphagous or peses. The azorean encomofauna is relatively poor in num ber of species and ende­

mics (O ROMI, 1982; Q UARTAU, 1982; M ENDES, 1982; MACHADO, 1982; ILHARCO, 1982; BAEZ, 1982; BORGES, 1990; VIEIRA & PINTUREAU, 1991). Argyresthia atlantieella, Aseotis fortunata azoriea and Cyc!ophora azorensis are azo­rean endemics. O n the other hand, Pittosporum undulatum is not a suitable host for these and other species of insects, present in Myriea-Eriea stands. Myriea­Eriea stands in che Azores islands are endangered by human activities and by the spread of exotic species, namely Pittosporum undulatum (DROUET, 1866; S]OGREN, 1984; Q UEIROS, 1987). Further spread of the exotic plant, an unsui­table host for several phytophagous insec ts supported by Myriea faya and Eriea seoparia ssp. azoriea, will affect not on ly the flora but aIso the entomofauna.

CONCLUSION

O f the lepidop tera found none is specific to Myriea faya. O n the other hand, we can conclude that lep idoptera are important phytophagous in Myriea­Eriea stands in lhe Azores Islands. N o other species of insects specific to Myriea faya were found in the Azores, so that, no more species will be sent to Hawaii as biocontrol agents.

Since Caloptilia aurantiaea is not specifie to Myriea faya no fu nher intro­ductions of this inseet should be allowed in H awaii.

If we are to preserve the natural eeosystems of the Azores, it does nOt suffi­ce ro p reserve che native flora, but also the associated entomofauna, and the trophic relationships that characterize those ecosystems. To achieve that goal, weed control measures should be reinforced.

186 L. Silva y j. Tavares

ACKNOWLEDGEMENTS

T hanks are due to Passos de Carvalho (Estação Agronómica Nacional, O eiras, Portugal), H. Shanderl, A. O nofre, and P. Borges ( niversidade dos Açores, Portugal), and to the taxonomists of the Imernational Instiru te of Emomology (London, UK), for the iden ti fi cation of various insects. Also to

V Vieira (Universidade dos Açores) for his sciencific and techn ical suppore. To C lifford Smith (Universi ty of H awaii) and George Markin (Forest-Service) for their support an d advice. To Fernando Almeida and José Viveiros for their supporr in field-work. T his work was partly supporred by the Coopera tive N ational Park Resources Srudies Unit, Botany D eparement, University of Hawaii.

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