Mating stimulates female feeding: testing the implications for the evolution of nuptial gifts

Nutritional benefits from nuptial gifts have been difficult to detect in some species, raising the question: what maintains nuptial feeding when gifts do not benefit females? The sensory trap hypothesis proposes that nuptial feeding may be explained by pre-existing sensory responses that predispose females to ingest gifts. Recent studies have shown that male seminal proteins can induce a nonspecific increase in female feeding after mating, which may represent a sensory trap for nuptial feeding if it results in increased intake of post-mating gifts. I tested these ideas using female beetles that ingest a spermatophore after mating. I show that males stimulate strongly increased female feeding post-mating. However, there was little evidence for dose dependence in the feeding response that could allow males to stimulate feeding beyond the female optimum. Moreover, the post-mating feeding response could not explain nuptial feeding: despite feeding more in general, newly mated females were less likely than nonmated females to ingest spermatophore gifts.