Obligatory multiparasitism in the tussock moth, Orgyia leucostigm

Orgyia leucostigma haemocytes were able to encapsulate and destroy eggs of Hyposoter species, thereby preventing successful parasitism. When host larvae had previously been parasitized by Cotesia melanoscela, however, this response was not observed, and 3 different Hyposoter species could be reared to maturity in the normally non-permissive host. Appropriate injection experiments established that C. melanoscela virus and venom were both, required in order for successful parasitism by Hyposoter to occur. Covalent cross-linking of C. melanoscela viral DNA led to an immune response against Hyposoter larvae, but not eggs, suggesting that an active viral genome may be required for complete development of Hyposoter species in tussock moth larvae.