SIMULTANEOUS INFLUENCE ON MALE COURTSHIP OF STIMULATORY AND INHIBITORY PHEROMONES PRODUCED BY LIVE SEX-MOSAIC DROSOPHILA-MELANOGASTER

Stable strains of Drosophila melanogaster flies producing mosaic sex-p heromones were created by manipulating the sex-determination gene tran sformer in different cellular patterns. Chromosomally male flies produ ced molecules that were partly or totally feminized, depending upon th e strain. The influence on male courtship behaviour of live flies prod ucing different mixtures of male and female pheromones was measured. T he intensity of the male response was mainly a function of the stimula tory effect of 7, 11 nonacosadiene and 7, 11 heptacosadiene, two femal e pheromones, combined with the inhibiting effect of 7-tricosene, the male predominant molecule. These compounds were effective at very diff erent doses. The influence of secondary molecules on male behaviours w as also evaluated. The role of these substances is discussed with rega rd to their structure, sexual specificity, and evolutionary function.