Immune defense in Drosophila melanogaster depends on diet, sex, and mating status

Immune defense is a complex trait that affects and is affected by many other host factors, including sex, mating, and dietary environment. We used the agriculturally relevant fungal emtomopathogen, Beauveria bassiana, and the model host organism Drosophila melanogaster to examine how the impacts of sex, mating, and dietary environment on immunity are interrelated. We showed that the direction of sexual dimorphism in immune defense depends on mating status and mating frequency. We also showed that post-infection dimorphism in immune defense changes over time and is affected by dietary condition both before and after infection. Supplementing the diet with protein-rich yeast improved post-infection survival but more so when supplementation was done after infection instead of before. The multi-directional impacts among immune defense, sex, mating, and diet are clearly complex, and while our study shines light on some of these relationships, further study is warranted. Such studies have potential downstream applications in agriculture and medicine.