Padrões de co-ocorrencia em insetos endofagos associados a capitulos de Trichogoniopsis adenantha (DC) (Asteraceae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

Immature endophagous insects develop inside host structures which offer them protection but, on the other hand, they have lower mobility, which increase the risks of competition and exposure to specialised natural enemies. Trichogoniopsis adenantha is an asteraceous herbs that found flowers throughout the year in Serra do Japi, Jundiaí, SP, Brazil. There is a small interval, in which flowers are scarce, especially during the dry winter. The flowers, when available, are frequently infested by endophages. This species was chosen to study the patterns of coocurrence of endophagous insects in asteraceous flowerheads. For one year, from July 1995 to July 1996, 15 samples were made. I collected 3329 mature flowerheads from 295 host plants. Ali mature flowerheads were kept in individual vials, until adults emerged, after which ali flowers were dissected to identify remaining puparia. Different species may show different coocurrence patterns, due to competitive interactions. These interactions can be manifest at different spatial and structural levels. The levels studied were: flowerheads, shoots, plants and patches. The way flowerheads are used by the endophagous species may show how resources are partitioned, 50 I also noted: number of used flowers or fruits, and the way these structures were used. Isolated plants may be found and used by endophagous insects in different ways, which can cause changes in the coocurrence patterns among species. Isolated individuais of T. adenantha are taller and bear more mature flowerheads. On the other hand, its flowerheads complete development earlier, and with smaller sizes than flowerheads from host plants in patches. Six species of endophagous insects were reared from T. adenantha: Trupanea sp. And Xanthaciura chrysura (Dip.: Tephritidae), Melanagromyza sp. (Dip.: Agromyzidae), Asphondy/ia sp. (Dip.: Cecidomyiidae); Adaina bipunctata (Lep.: Pterophoridae) e Phalonidia unguifera (Lep.: Tortricidae). Ali species were found throughout the year, but in different Isolated plants were infested by insects in the same proportion of plants in patches, although their flowerheads were comparatively less attacked. Trupanea was found in more flowerheads from plants in patches, possibly because this species prefers larger flowerheads. The opposite happened to Melanagromyza. Trupanea, Melanagromyza and Asphondy/ia (the three more abundant species) coocurred in flowerheads less often than expected by chance. These species. on the other hand, coocurred more often than expected on the same shoots and plants. This result suggests that different processes may be operating at different levels of resource

ASSUNTO(S)

relação inseto-planta diptero ecologia

ACESSO AO ARTIGO

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