Insemination patterns in HawaiianDrosophila species (Diptera: Drosophilidae) correlate with ovarian development

Abstract

In 35 Hawaiian Drosophilaspecies collected from natural populations, all reproductively mature females were inseminated. Onset of receptivity to insemination broadly correlated with the vitellogenic stage of ovarian development, but species and species groups varied in the exact stage of vitellogenesis at which earliest insemination took place. A striking exception was observed in two picture-winged species of the adiastolasubgroup, which were precociously inseminated in previtellogenesis, close to the time of adult eclosion. For a given species, the range of ovarian stages from earliest receptivity to insemination of all females, termed the “insemination period,” also varied among species. This variability may be due to physiological variation between females in hormonal levels, low population densities, and lek behavior of males, or it may reflect variation in degree of female discrimination toward male courtship attempts. Consideration of the quantities of sperm observed stored in the female sperm storage organs, relative to the numbers of eggs produced, indicates obligatory multiple insemination for some species, notably the fungus breeders. In other species groups, there is no apparent necessity for remating, although it may occur.