Identification of the pheromone of the Comstock mealybug

The Comstock mealybug, Pseudococcus comstocki (Kuwana) is a tiny insect that is a serious agricultural pest of citrus, pomegranates, and other fruit in California and elsewhere throughout the world. The fungus that forms on the insect secretions causes severe smutting and results in economic losses to fruit growers. The female insects emit a sex pheromone that attracts males, and traps containing live females have been used to detect infestations. This pheromone has now been isolated from volatiles trapped from an air stream passed over the insects. The identification as 2, 6-dimethyl-1, 5-heptadien-3-ol acetate was made on the basis of chromatographic and spectroscopic data of the natural material and its derivatives. This is the first pheromone identified from the mealybug family and its norterpene (9-carbon) skeleton is uncommon among insect pheromones. The compound was synthesized and shown to be highly attractive in field bioassay at concentrations as low as 0.2 μg per trap.