Insights into function and evolution of parasitoid wasp venoms

Most species in the order Hymenoptera are parasitoids that lay eggs and develop in or on the body of arthropod hosts. Several factors contribute to successful parasitism including venoms that wasps inject into hosts when ovipositing. Here, we review the composition, function and diversity of parasitoid venoms with emphasis on studies of wasps that parasitize hosts in the genus Drosophila. The comparative literature indicates that some closely related species parasitizing the same host do not share any abundant venom protein while unrelated species sometimes have the same major venom component. Within species, studies also identify intraspecific variation that suggests parasitoid venoms may rapidly evolve. Overall, however, our picture of venom function remains largely unclear and will require additional comparative data on the composition of venoms from a greater diversity of species than exists currently. Further advances will come mainly from experimental data using functional tools, such as RNA interference.