D3216: Identification of a four-component pheromone blend in Ibalia leucospoides, a parasitoid of Sirex noctilio

Ibalia leucospoides (Ibaliidae) is a wasp parasitoid that has been broadly employed as a biological control agent for the management of the European woodwasp, Sirex noctilio (Siricidae) in the Southern Hemisphere. In this study, we described identificaion of sex attractants for I. leucospoides under laboratory conditions. GC-EAD analysis of female body washes with male antennae showed seven antennally active components, four of which are tricosene, pentacosene, hexacosene, and heptacosene. The biological activity of these straight-chain alkanes was confirmed in olfactometer assays. A four-component blend of C₂₃, C₂₅, C₂₆, C₂₇ in a 1:100:300:450 ratio was significantly more attractive than the solvent control. there was no response to blends that lacked any of these four compounds. Female body wash was no more attractive than the four-component blend. The chain lengths and therefore the volatility of the identified alkanes in cuticular hydrocarbons of I. leucospoides females suggest short-range activity.