Biologically active cuticular compounds of female Sirex noctilio

The Eurasian woodwasp Sirex noctilio Fabricius (Hymenoptera: Siricidae) is a major invasive pest in pine plantations of the Southern Hemisphere. In this study, we aimed to identify pheromone compounds in S. noctilio females, for potential use in lures for pest monitoring and control. An examination of S. noctilio body washes resulted in the identification of a behaviorally active compound, 10-oxo-decanoic acid (10-ODA), that is derived from cuticular hydrocarbons of females. This oxocarboxylic acid is likely produced through oxidative reactions at the cleavage of double bonds of certain female-produced cuticular dienes. Gas chromatography-electroantennogram detection (GC-EAD) analyses showed that only male antennae consistently responded to natural and synthetic 10-ODA. In olfactometer assays, 10-ODA alone was attractive to S. noctilio males, although males marginally preferred the combination of 10-ODA and nonanal, compared with 10-ODA alone. This suggests pheromonal activity of this compound. However, no wasps were captured in initial field trapping experiments with 10-ODA and further work is required.