Diet affects insemination and sexual activity in male Phormia regina (Diptera: Calliphoridae)

A proteinaceous diet is essential for male black blow fly, Phormia regina (Meigen), to successfully inseminate females and can be obtained naturally from feces or gleba. Sugar-fed males inseminate a low percentage of females (8-14%) compared with liver-fed males (>75%). If, however, liver-deprived males are kept with liver-fed females for 24 h, males are able to obtain their dietary requirement for mating by feeding on female feces or vomit spots. Using a fluorescent dye mixed with the beef-liver diet fed to females, it was demonstrated that nonliver-fed males consume feces or vomit spots from these flies. If liver-deprived, either sex will exhibit licking behavior, which is directed only at liver-fed flies. This behavior to acquire an essential component from the liver diet may have been the original function of the anal-genital licking behavior observed in several species of Drosophila and is now part of their courtship ritual.