PHEROMONE PRODUCTION IN SESAMIA-NONAGRIOIDES - DIEL PERIODICITY AND EFFECT OF AGE AND MATING

Diel periodicity of pheromone production and the effect of age and mating on the pheromone titre of the female Sesamia nonagrioides (Lef.) was studied. The pheromone titre was measured by quantitative capillary gas chromatographic analysis. Females began producing pheromone 20-24 h following emergence. The higher quantity of pheromone was measured during the second scotophase. The pheromone gland contained detectable quantities 2 h after the onset of the scotophase and reached maximal levels during the sixth hour in the second scotophase. The pheromone titre was very low 2 h after the onset of the photoperiod. Females began calling 4 h after the onset of the scotophase and peak calling activity was observed at the sixth hour. Mating suppressed pheromone biosynthesis. The quantity of pheromone measured in mated females 24, 48 and 72 h after mating was significantly lower than that of virgin females of similar age.