Circadian Rhythmicity of Sex Pheromone Release by Dioryctria abietella (Lepidoptera: Pyralidae (Phycitinae)) and the Effect of a Diel Light Cycle on Its Precopulatory Behavior1

Abstract

The extent to which male moths of Dioryctria abietella (Denis and Schiffermüller) passed through successive stages of precopulatory behavior was dependent on the concentration of sex pheronione. Pheronione responsiveness of males and female production of the sex pheromone were influenced by diel cycles of 12 hours of light: 12 hours of darkness (12L: 12D). The quantity of pheronione present on abdominal tips of females decreased during photophase and was maximum 9 hours after onset of scotophase during periods of peak calling activity. The duration of male responsiveness to the pheromone was about twice as long as the period of female release during the 12L:12D photoperiods. Female production and release of the sex pheromone, as well as male responsiveness to the pheromone, were inhibited by light. Periods of locomotor activity and calling behavior of female moths followed a circadian rhythm that appeared to be endogenously timed but strongly entrained to imposed photoperiods.