Sex pheromone of the aerial root mealybug, Pseudococcus baliteus: A unique monoterpenoid containing an α-hydroxyketone moiety

[Display omitted] •A hitherto-unknown monoterpenoid was discovered as a mealybug pheromone.•Comparisons of the natural and synthetic products determined the configuration.•This compound including an α-hydroxyketone moiety is unique in insect pheromones. A single compound that elicited an electrophysiological response from conspecific male antennae was isolated from volatiles emitted by adult females of the aerial root mealybug, Pseudococcus baliteus. Mass spectrometry and nuclear resonance spectroscopy analyses, as well as enantioselective syntheses, revealed the structure to be 2-((S)-1,2,2-trimethyl-3-cyclopentenyl)-2-oxoethyl (S)-2-methylbutyrate. This ester, which is a hitherto-unknown monoterpene with an α-hydroxyketone moiety, displayed attractiveness to adult males and was concluded to be the P. baliteus sex pheromone.