Attractiveness of citronellol identified from Rosa chinensis volatiles to the thrips pest Frankliniella occidentalis and its beneficial effect on population development

Frankliniella occidentalis is a serious pest of various plant species and has different olfactory preferences for different host plants. Here, the olfactory responses of female F. occidentalis to the volatiles from different plants (Rosa chinensis, cucumber, and tomato) were tested using electroantennography (EAG) and behavioral bioassays in different types of olfactometers. Y-tube olfactometer bioassays indicated that R. chinensis was the preferred host for F. occidentalis. Fifty-five compounds were identified as components of the volatiles of R. chinensis by gas chromatography–mass spectrometry analysis, of which citronellol (11.62%), 1-hexanol (11.28%), and 3,5-dimethoxytoluene (11.45%) showed the highest relative abundance. EAG recordings showed that antennae of F. occidentalis were able to perceive these three compounds at a wide range of concentrations. In six-arm olfactometer bioassays, F. occidentalis showed significant positive responses to citronellol and 1-hexanol at various concentrations, with the most attractive ones being 10 μg/μL for citronellol and 1 μg/μL for 1-hexanol. When these two compounds at their optimal concentrations were placed in a four-arm olfactometer, significantly more F. occidentalis individuals were attracted to citronellol. F. occidentalis populations were significantly increased under the stimulation of citronellol at 10 μg/μL. Our results show that plant semiochemical volatiles play an important role in the host plant detection and selection of F. occidentalis, and they help guide it to preferred host plants that are suitable for its reproduction. Citronellol showed the greatest potential for development as a novel monitoring and control tool against this thrips species.