A cost of mating with males that do not transfer sperm in female Drosophila melanogaster

Abstract

The aim was to test for effects of accessory fluid and sperm on female survival, by comparing females that received both (exposed continuously to wild-type males), lowered sperm (exposed intermittently to XO males, which transfer no sperm at mating) or lowered sperm and accessory fluid (exposed intermittently to wild-type or XO males with their external genitalia microcauterized and which therefore transfer neither sperm nor accessory fluid). Within females exposed to XO males, male microcautery improved female survival, indicating a cost of mating with XO males. This cost cannot be attributed to an effect of sperm-transfer. For both microcauterized and intact males, females exposed to XO males survived longer than females exposed to wild-type males. There must therefore have been a difference in the non-mating costs of exposure to XY and XO males, and the lower levels of courtship by XO males, associated with lower levels of female movement, may have been responsible. Because of this difference in non-mating costs, it was not possible to test for costs of receiving sperm or accessory fluid.