A QUANTITATIVE BIOASSAY FOR SEX PHEROMONE OF EPIPHYAS POSTVITTANA (LEPIDOPTERA) AND FACTORS LIMITING MALE RESPONSIVENESS

Observations were made on the mating behaviour of the light-brown apple moth, Epiphyas postvittana, and a quantitative biossay for the female sex pheromone was devised. Direct and indirect effects of light intensity produced significant changes in the levels of male light-brown apple moth responsiveness to the pheromone; light intensities greater than 3·5 lx suppressed the male response and, via the timing of a circadian rhythm, light/dark cycles established a set period of peak responsiveness within a diel cycle. Male moths attained their peak responsiveness to the sex pheromone by the second night after emergence, and this level was maintained until at least the tenth night. Previous exposure to the sex pheromone within the same diel cycle caused a lowering of percentage response to subsequent treatments. © 1969.