Aggregation pheromone characterization and comparison inDrosophila ananassae andDrosophila bipectinata

(Z)-11-Octadecenyl acetate (Z11-18∶Ac) and (Z)-11-eicosenyl acetate (Z11-20∶Ac) were identified as the aggregation pheromones ofDrosophila ananassae, andZ11-20∶Ac was identified as the aggregation pheromone ofDrosophila bipectinata. Z11-18∶Ac andZ11-20∶Ac were not attractive alone; however, in combination with fermenting food odors, the acetates attracted flies of both sexes in a wind-tunnel olfactometer. The pheromones were present in the ejaculatory bulb of sexually mature male flies and transferred to the female during mating. MaleD. bipectinata released little if anyZ11-20∶Ac to the food; however, recently mated females releasedZ11-20∶Ac to the surrounding surfaces in just a few hours after mating.D. ananassae males, on the other hand, appeared to release moreZ11-18∶Ac andZ11-20∶Ac to the surroundings than mated females. AlthoughD. bipectinata males had noZ11-18∶Ac, flies were as attracted toZ11-18∶Ac as to an equal quantity ofZ11-20∶Ac.D. ananassae were attracted toZ11-18∶Ac but not toZ11-16∶Ac orZ11-20∶Ac. However,Z11-20∶Ac in combination withZ11-18∶Ac was significantly more attractive thanZ11-18∶Ac alone.