Aggregation pheromone ofDrosophila mauritiana,Drosophila yakuba,andDrosophila rajasekari

(Z)-11-Octadecenyl acetate (Z11–18Ac) was identified as the aggregation pheromone ofDrosophila mauritiana, D. yakuba, andD. rajasekari. The amount of pheromone in the ejaculatory bulb of male flies increased with age, reaching plateau levels of ca. 240, 800, and 1100 ng/fly forD. mauritiana, D. yakuba, andD. rajasekari, respectively. Thirty to 50% of the pheromone in the ejaculatory bulb was transferred to the female during mating, with the majority transferred to the female's reproductive tract. In the subsequent 6-hr period, over half the pheromone in the female's reproductive tract was transferred to the surroundings. In a wind-tunnel olfactometer,Z11–18Ac was attractive toD. yakuba andD. mauritiana; however,D. rajasekari required food or food odors in combination withZ11–18Ac to demonstrate aggregation activity.Z11–16Ac andZ11–20Ac were not attractive forD. mauritiana, D. yakuba, andD. rajasekari. For all three species, food was synergistic withZ11–18Ac and both sexes were attracted.