Rapid and differential evolution of the venom composition of a parasitoid wasp depending on the host strain

AbstractParasitoid wasps rely primarily on venom to suppress the immune response and regulate the physiology of their host. Intraspecific variability of venom protein composition has been documented in some species, but its evolutionary potential is poorly understood. We performed an experimental evolution initiated with crosses of two lines ofLeptopilina boulardiof different venom composition to generate variability and create new combinations of venom factors. The offspring were maintained for 10 generations on two strains ofDrosophila melanogasterdiffering in resistance / susceptibility to the parasitoid lines. The venom composition of individuals was characterized by a semi-automatic analysis of 1D SDS-PAGE protein profiles whose accuracy was checked by Western blot analysis of well-characterized venom proteins. Results evidenced a rapid and differential evolution of the venom composition on both hosts and showed that the proteins beneficial on one host can be costly on the other. Overall, we demonstrated the capacity of rapid evolution of the venom composition in parasitoid wasps, important regulators of arthropod populations, suggesting a potential for adaptation to new hosts. Our approach also proved relevant in identifying, among the diversity of venom proteins, those possibly involved in parasitism success and whose role deserves to be deepened.Key ContributionThe venom protein composition of parasitoid wasps can evolve rapidly and differently depending on the host strain. Studying this evolution can help identify new venom proteins possibly involved in parasitism success on a given host.