Effects of male paragonial gland secretion on sexual receptivity and courtship behaviour of female Drosophila melanogaster

Female Drosophila melanogaster show a switch-off in sexual receptivity and an increase in oviposition rate following impregnation. These effects are also observed in unfertilized virgin females which receive transplants of intact male paragonia into the abdominal body cavity. Virgin Amherst wildtype females show a repertoire of responses to male courtship characterized by high rates of kicking and fending and a low rate of genital extrusion. Fertilized females show low rates of kicking and fending but a high rate of genital extrusion. Virgin female hosts receiving paragonial gland implants show an altered pattern of courtship rejection with low rates of kicking and fending. Studies on these host females, and on females homozygous for the mutant allele female-sterile, suggest that the expression of genital extrusion depends, in addition to the paragonial gland substance, upon additional information input from abdominal stretch receptors or from the ovary.