Functional response and superparasitism by Diachasmimorpha longicaudata (Hymenoptera : Braconidae), a parasitoid of fruit flies (Diptera : Tephritidae)

The functional response and the effect of superparasitism of Diachasmimorph a longicaudata (Ashmead) in larvae of Anastrepha ludens (Loew) was determin ed under laboratory conditions. Adult parasitoids were tested individually and in groups of 5. Third-instar A. ludens larvae were exposed for 3 h to e xperienced, 5-d-old females at the ratios of 1, 5, 20, 30, 40, 50, and 60 h ost larvae Der wasp For individual females, functional response was type II I, whereas for females in groups, a type II curve was observed. In the pres ence of conspecifics, females increased their parasitization activity. Fema les showed a strong tendency for self-superparasitism (the same female layi ng >1 egg in the same host) with a range of 38.9-57.9% of larvae superparas itized, even when there was no competition and a high availability of host larvae. In the superparasitism experiment, when the parasitoid/host ratio w as 1 or greater, larval mortality was consistently high but never exceeded 90%. Successful parasitoid emergence decreased as the parasitoid/host ratio increased. We discuss and question the detrimental effects that have been attributed to superparasitism in solitary endoparasitoids.