Multifaceted Defenses Against Parasitoid Wasps in Diptera

Parasitoid wasps are a large and diverse group of species that infect a wide variety of insect hosts. In response, hosts have evolved numerous defensive strategies to protect against infection. Here, we review the immune and behavioral defense responses of the fruit fly Drosophila melanogaster against parasitoid wasps, the best-characterized dipteran system for host-parasitoid interactions. The melanotic encapsulation of parasitoid eggs is a highly conserved immune response that defends hosts against both coevolving and novel parasitoid species while simultaneously protecting against self-inflicted immune damage. Behavioral defense mechanisms include parental behaviors to protect offspring from infection and adaptive alterations in infected juveniles. We discuss the genetic basis and conserved mechanisms of these responses and identify exciting questions for future research.