Volatiles of several grapevine cultivars emitted at different phenological stages linked to discriminatory ability of grapevine moths

The tortricid moths Lobesia botrana (Denis and Schiffermueller) and Eupoecilia ambiguella (Hübner) are major insect pests of grapevine Vitis vinifera. We compared the pattern of volatile organic compounds in headspace samples of four different grapevine cultivars in dependency of their phenological stage by thermodesorption coupled with gas chromatography (GC) and mass spectrometry. Further, we assessed the detection of compounds by the antenna of both moth species by GC coupled with electroantennographical detection. We detected significant differences between the chemical compositions of headspace samples of the four cultivars based on the odor bouquet. By comparing the principal component linear discriminant analysis pattern of only those chemical compounds that could be actually detected by the moths’ antenna, the different cultivars showed similar odor patterns indicating that differences measured by GC may not be detected by the moths’ antenna. The supposed reduced discriminatory ability of both moth species was supported by behavioral bioassays using a Y-tube olfactometer. In connection to the recently published impact of the berries’ visual appearance (shape and color) and nonvolatile compounds of the wax layer, the presented results suggest that reported moth preferences for specific cultivars are not encoded by volatiles only. The results of this study will contribute to the development of an innovative egg-monitoring tool for grapevine moths.