Role of leaf volatiles in spotted-wing drosophila attraction to blueberry fruits

Habitat selection by insects is a critical first step in locating suitable hosts for feeding, mating, and oviposition, thereby ensuring their survival and reproductive success. Odors play a central role in this process, as insects rely on specific chemical cues to detect and orient toward preferred habitats and hosts. The spotted-wing drosophila (Drosophila suzukii), an invasive pest of thin-skinned small fruits, uses fruit odors to locate suitable oviposition sites. Unlike most other Drosophila species, D. suzukii targets ripening fruit. However, it remains unclear whether host plant odors enhance their attraction to fruit. We conducted a series of laboratory and semi-field experiments to test the hypothesis that leaf volatiles enhance the attraction of D. suzukii to fruit. Additionally, we identified specific volatiles that may mediate this response. Choice assays showed that both male and female flies were more attracted to fruit volatiles when leaf volatiles were also present, compared to fruit volatiles alone. Similarly, laboratory and semi-field cage experiments revealed higher oviposition rates when leaves were included with the fruit. Volatile analysis of fruits and leaves indicated a distinct shift in the volatile profile when leaves were present, with 23 compounds emitted in significantly higher amounts. Of these, nine compounds were selected for subsequent tests in behavioral assays to assess their role in attraction. Overall, our results demonstrate that D. suzukii’s attraction to fruit volatiles is enhanced by the presence of leaf volatiles, suggesting that habitat selection and host location are context-dependent and mediated by a combination of plant-derived cues.