Separate orientation and releaser components in a sex pheromone

Abstract

The sex pheromones, with which female moths attract males, normally consist of a mixture of several chemicals, usually aliphatic alcohols, acetates and aldehydes¹. In the small number of species which have been studied in detail, particular combinations of compounds have been shown to elicit each of the major stages of the approach of the male to the female^2–4. However, little distinction has been made between the chemical signals which allow the male to orientate towards the female, and those which elicit specific responses such as landing and courtship behaviour. Recent studies on the mechanisms whereby male moths navigate towards pheromone-producing females have concentrated on single chemicals, or fixed blends of chemicals, and have not considered the separate roles of individual compounds within a blend^5,6. In our studies of the responses of male pine beauty moths, Panolis flammea (Schiff.) to the sex pheromone produced by the female, we have now demonstrated that both landing and copulatory behaviour are elicited by different chemical stimuli to those which serve to orientate the male at each of these stages.