Genetic evidence that ovulation reduces sexual receptivity in Drosophila melanogaster females.

Drosophila females start ovulation shortly after mating, and at the same time they become unreceptive to courting males. Both physiological changes are induced by the "sex-peptide" derived from the male accessory glands. It is conceivable, therefore, that the first effect of the peptide is to induce ovulation, and some signal derived from ovulated eggs makes females unreceptive. To test this hypothesis, I examined the mating receptivity of virgin D. melanogaster females homozygous for lozenge mutants that showed a high-frequency spontaneous ovulation. These females were reluctant to mate. However, when mature eggs were genetically deprived using nonallelic female sterile mutants, their receptivity increased significantly, although mating speed was still slower than that of normal virgin females. Essentially the same was found with the females that were ectopically expressing the sex-peptide gene. The results indicate that ovulation induced by the sex-peptide has an effect of reducing the sexual receptivity of mated females.