The sex-peptide.

Injection of a peptide of 36 amino acids into virgin Drosophila females changes their reproductive properties drastically: males are rejected and egg laying is increased. The neuronal and physiological properties of the virgin state are replaced by a new pattern of behavior and stimulation of egg production and deposition. Under natural conditions, the peptide is synthesized by the male and transferred into the female during copulation. The sex-peptide, therefore, can be considered as a pheromone. In this review, I shall limit my discussion to Drosophila melanogaster.