Hormonal control of motivational circuitry orchestrates the transition to sexuality in Drosophila

SUMMARY Newborns and hatchlings of many species perform incredibly sophisticated behaviors, but all vertebrates and many invertebrates selectively abstain from sexual activity at the beginning of life. Hormonal changes have long been associated with adolescence, but it is not clear how these circulating factors create a new motivation and drive its associated behaviors. We show that the transition to sexuality in male Drosophila is controlled by juvenile hormone, which spikes at eclosion and declines over days as the propensity for courtship gradually increases. Juvenile hormone directly inhibits the activity of at least three courtship-motivating circuit elements, ensuring the complete suppression of sexual motivation and behavior. Blocking or overriding these inhibitory mechanisms evokes immediate and robust sexual behavior from very young and otherwise asexual males. These results provide a first example of hormonal changes gating the transition to sexuality by activating latent, but largely developed and functional, motivational circuitry.