Male acceleration of ovarian development in Drosophila silvestris (Diptera, Drosophilidae): What is the stimulus?

In the fly Drosophila silvestris the onset of vitellogenesis is accelerated when sexually immature adult females are housed with mature males, We examined the proximate stimuli that could be responsible for this acceleration. This stimulus could be courtship, because mature males will court immature females. By housing females on the opposite side of a divided jar from males, we could isolate females from courtship stimuli, but allow them access to airborne and substrate chemicals, Females housed in that way did not show acceleration, However, when the females were housed on the opposite side of the jar from mature males, but the food dishes were moved daily, some acceleration occurred, When females were housed in undivided jars, with complete access to males, but with the food dishes being replaced by fresh food daily, no acceleration was found, This suggests that some aspect of food that has been exposed to mature males, perhaps a bacterium growing on its surface, is providing a nutritional supplement which allows acceleration of ovarian development. Copyright (C) 1996 Elsevier Science Ltd