Bioassay of a Drosophila pheromone influencing sexual selection

Abstract

PHEROMONES function by transmitting information from a sending to a receiving organism by chemical means. In a classic paper, Bossert and Wilson classified the effects of such information transfer into releasing and priming¹. Releaser pheromones evoke an immediate overt behavioural effect, whereas primer pheromones activate the chemoreceptor in such a way as to alter the physiology of the receiving organism^1,2. In general, studies involving the isolation identification of pheromones have concentrated on releasers such as sex attractants, alarm pheromones, trail pheromones and aggregation pheromones³. The advantage of using releaser pheromones in such studies is that the behavioural effects can be observed even in a single individual of the appropriate age, sex and species. This makes the development of a relatively simple and rapid bioassay a straightforward process. So far the important exception to the use of releaser pheromones has been the work of Butler et al. showing that 9-ketodecenoic acid inhibits ovarian development in worker bees⁴. This substance, however, was first identified as the sex attractant of the queen bee and later shown to have a primer effect. We describe here a bioassay for a substance with an effect which does not fit easily into either the releaser or primer category.