An overlooked component: (Z)-9-tetradecenal as a sex pheromone in Helicoverpa armigera

The sex pheromone blend of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a multi-component system, as is that of many other moths, and (Z)-11-hexadecenal 90-99%+(Z)-9-hexadecenal 10-1% was recommended as a standard blend for attracting the species. However, this fails to account for the significance of other compounds that exist in the sex gland. The aim of the present study was to investigate the function of other compounds present in the female sex gland of H. armigera. Extract of female sex glands were analysed by GC-MS combined with GC-EAD. Total 10 compounds were identified, which two novel were reported in female sex gland: heptanal and nonanal, and some previously identified compounds were confirmed. We developed bioassays to evaluate the potential roles of these 10 compounds. In Y-tube bioassays, the gland constituents hexadecanal, (Z)-7-hexadecenal and (Z)-9-tetradecenal increased male attractiveness when added as a three-compound admixture to the standard blend. Field trapping tests showed that (Z)-9-tetradecenal doubled trap catch in comparison with the standard blend, but that the addition of (Z)-7-hexadecenal and hexadecanal did not significantly increase trap catch. These results indicated that while (Z)-7-hexadecenal and hexadecanal function well only at short range, (Z)-9-tetradecenal plays a very important role at both short and long ranges. We suggest that that (Z)-9-tetradecenal as a previously overlooked sex pheromone component of H. armigera, it should be added to sex pheromone lure formulations to improve pheromone trap sensitivity and the efficacy of commercial mating disruption.