EGG-LAYING EXPERIENCE AND ACCEPTANCE OF PARASITIZED HOSTS BY THE PARASITOID, LEPTOPILINA-HETEROTOMA (HYMENOPTERA, EUCOILIDAE)

The influence of egg-laying experience on the response of females of t he eucoilid parasitoid, Leptopilina heterotoma, to parasitized and unp arasitized Drosophila melanogaster host larvae was examined under more controlled conditions than those used in past studies. In laboratory assays, we precisely manipulated both the number of eggs laid by femal es and the kind of larvae (parasitized versus unparasitized) in which the eggs were laid. We found that the tendency to avoid laying eggs in parasitized hosts depended markedly on whether or not eggs had been l aid previously, but depended little on whether those eggs had been lai d in parasitized or unparasitized hosts. The observed effect of genera l egg-laying experience on avoidance of parasitized hosts may reflect responses to either changes in the wasp's internal state (perhaps, cha nges in egg lend) or changes in the wasp's neural representation of th e external environment (such as those presumed to occur during learnin g). In light of these results, we offer a tentative reinterpretation o f several earlier studies.