Genetically-based variation in resistance to parasitoids in the fruit fly Drosophila melanogaster

The relationship between parasites and their hosts is an arms race, with adaptations increasing parasite success selecting for counter-adaptations for host resistance. A classic model is the wasp parasitoid Leptopilina boulardi, which uses virus-like particles against the encapsulation response of its host, the fruit fly Drosophila melanogaster. To determine whether encapsulation is the sole mechanism of resistance, we used 25 strains of the Drosophila Genetics Reference Panel to quantify resistance and identify its genetic basis. We found significant variation in parasitism success across fly strains even though none exhibited encapsulation, suggesting flies have more than just encapsulation in their repertoire.