Fruit flies prophylactically medicate offspring after seeing parasites. Todd A. Schlenke, Balint Z. Kacsoh, Zachary R. Lynch, Nathan T. Mortimer. Biol/O Wayne Rollins Res Ctr, Emory Univ, Atlanta, GA.

   Hosts have numerous defenses against parasites, of which behavioral immune responses are an important but under-appreciated component. Here, I describe a behavioral immune response Drosophila melanogaster utilizes against endoparasitoid wasps. I found that adult flies detect wasp presence by sight and undergo a neuropeptide F-mediated oviposition behavior switch to lay eggs in food containing toxic levels of alcohol, which protects hatched larvae from wasp infection. This change in oviposition behavior is retained even after wasps are removed in a process dependent on the canonical long-term memory gene Adf1. Flies respond to diverse female larval endoparasitoids but not against male larval or female pupal endoparasitoids, showing they have evolved specific wasp search images. Furthermore, the response evolved in parallel with ethanol tolerance multiple times across the genus Drosophila. My data uncover a novel behavioral immune response based on anticipatory medication of offspring, and outline a novel non-associative memory paradigm based on innate parasite search image recognition by the host.