Survival of the polyembryonic parasitoid Copidosomopsis tanytmema (Hymenoptera: Encyrtidae) in envenomized larvae of its host Anagasta kuehniella (Lepidoptera: Pyralidae)

Abstract

We investigated whether the endoparasitic encyrtid Copidosomopsis tanytmema Caltagirone could survive in host larvae envenomized by the braconid Bracan hebetor (Say). The former is a polyembryonic, egg-larval, species-specific parasitoid of the pyralid Anagasta kuehniella (Zeller). The latter is a solitary ectoparasitoid on fatally envenomized late instars of A. kuehniella and other pyralids. Our results indicate that C. tanytmema broods survive in envenomized hosts, although the proportion in a brood emerging as adults is reduced significantly. This reduction appears to be the result of polygerm failure and not death of C. tanytmema larvae, which were observed to survive well past the time that pupation normally occurs. Because polygerm development is seriously delayed but not aborted, and parasitoid larvae persist but do not transform, B. hebetor venom probably compromises parasitoid survival indirectly by gradually diminishing the quality of the host tissues required for C. tanytmema's development, rather than by directly intoxicating C. tanytmema polygerms and larvae. The implications for interspecific competition between C. tanytmema and B. hebetor are discussed.