Quantity of the male ejaculate influenced by female unreceptivity in the fly, Culicoides melleus

Abstract

The number of sperm placed in the spermatophore by virgin Culicoides melleus males mated with virgin females was compared with the number deposited in matings with previously once or twice copulated females. When compared to an all-virgin mating, there was a significant reduction ( P<0·001) in sperm complement (of 15 per cent) when the female had already been mated once as compared to a virgin, and a greater reduction (of 21 per cent) when the female had already been mated twice. The mean numbers (± S.E.) of sperm ejaculated with virgin, once mated, and twice mated females were 857 ± 24, 732 ± 23, and 673 ± 25, respectively. When a major activity in the unreceptive behaviour of females (kicking at the male in the early stages of copulation) was prevented by amputation of the hind legs, the mean number of sperm ejaculated (788 ± 29) was significantly larger ( P<0·01) compared with twice mated females having both legs intact, and also larger, though not significantly so, than with intact once mated females. In addition to the kicking activity, there was evidence that other forms of unreceptive behaviour contributed to reducing the quantity of sperm ejaculated.