Factors limiting the response of females of the Queensland fruit fly, Dacus tryoni, to the sex pheromone of the male

Factors limiting the responsiveness of female Dacus tryoni to the male sex pheromone were determined in laboratory bioassays. Maximum response occurred in bioassays carried out at the normal time of dusk under a light intensity of 0·8 ln/ft². The responsiveness of females decreased at light intensities above or below this value. Responsiveness was also influenced by an internal rhythm, the peak of which was synchronized with the start of dusk. The majority of females did not become responsive until their ovaries had matured and they all became unresponsive again for a period after mating. Four weeks after the first mating some females had regained their responsiveness.