Peach-specific aldehyde nonanal attracts female Oriental fruit moths, Grapholita molesta (Lepidoptera: Tortricidae)

The oriental fruit moth (OFM), Grapholita molesta (Lepidoptera: Tortricidae), is a serious pest of stone and pome fruit trees worldwide. G. molesta can switch hosts and produce multiple generations per year. Both the primary and secondary host plants of G. molesta emit aldehydes. Here, we tested whether these aldehydes are helpful for host switching of G. molesta. SPME (Solid Phase Microextraction)-GC MS analysis identified four aldehydes (octanal, nonanal, decanal, and benzaldehyde) from volatiles of late-season yellow peach fruits. Of the four aldehydes, eletroantennogram analysis showed that nonanal produced the strongest response from the antennae of virgin and mated females. In Y-tube bioassays, only nonanal was attractive to mated G. molesta females amongst the four aldehydes, suggesting that nonanal is important for host recognition in G. molesta. In a field trial, each of the four aldehydes was tested as an attractant for both sexes of G. molesta. The traps baited with nonanal captured more female G. molesta, as compared to traps with other aldehydes and control; the traps baited with benzaldehyde captured most male G. molesta. Our research investigations provide theoretical foundation for biological control of G. molesta females. Future G. molesta lure designs should take into account sex-specific differences in the response to individual aldehydes.