Interactions between the parasitoid Ametadoria misella (Diptera : Tachinidae) and the granulovirus of Harrisina brillians (Lepidoptera : Zygaenidae)

Interactions between a granulovirus (HbGV), a tachinid parasitoid Ametadori a misella, and their host, the western grapeleaf skeletonizer Harrisina bri llians, were investigated. In field populations, the occurrence of A. misel la in HbGV-infected H. brillians pupae was less frequent than would have be en expected by random assortment of the virus and the parasitoid. Furthermo re, enzyme-linked immunosorbent assay detected granulovirus less frequently and in lower concentrations in parasitized pupae than in nonparasitized pu pae. Finally, in the host pupae that tested positive for virus, parasitoids were more likely to survive pupation than hosts. When laboratory-reared H. brillians larvae were exposed to naturally occurring A. misella in a held experiment, the parasitoid oviposited more often in older than in younger h ost larvae and more often in healthy than in HbGV-infected host larvae. The se results are consistent with the hypothesis that selective oviposition by A. misella leads to reduced overlap of the parasitoid and HbGV in hosts, r esulting in greater parasitoid survival, (C) 1999 Academic Press.