Pheromonal control of mating patterns inDrosophila melanogaster

Multiple-choice mating tests comparing the mating propensity among and within inbred lines were performed forDrosophila melanogaster. Courtship activity, time to copulation, and assortative mating were all directly correlated with the degree of inbreeding. By the eighth generation of sib mating, there was a 76% incidence of negative assortative mating in multiple-choice tests and a marked reduction of courtship behavior among sibs. Furthermore, absence of sperm in the females of nonreproductive pairs indicated that much of the attrition of inbred lines was due to failure of sibs to mate. When individuals of sterile cultures were allowed an opportunity to outcross, most were fertile and exhibited normal mating and courtship activity. Olfactometer tests with either unrelated flies or collected pheromone samples as source material indicated that airborne chemosignals are required for initiation of courtship inD. melanogaster. Visual and audio cues were found to be noncritical inD. melanogaster courtship and mating. Intraspecific qualitative pheromone variation, at one or a few loci, is thought to be functioning as the control mechanism in selective mating.The investigation was conducted as partial fulfillment of the requirements for the degree of Doctor of Philosophy by W. W. A. while he was supported by PHS Training Grant No. 5T01 GM-00337 from the National Institutes of General Medical Sciences. Other research support was by NSF Grant GB 36103X to R. H. R. The support of NIH Research Career Development Award 5 KO4-GM 47350 to R. H. R. also is acknowledged.