Role of leaf volatiles in spotted-wing drosophila (Diptera: Drosophilidae) attraction to blueberry fruits.

Herbivorous insects use volatile organic compounds (VOCs) to find food, mates, and oviposition sites. Understanding these cues is key for behavior-based pest management. Spotted-wing drosophila (Drosophila suzukii Matsumura) (Diptera: Drosophilidae) is an invasive pest that attacks ripening fruit. Although fruit VOCs attract this species, the role of nonfruit plant volatiles, such as those emitted by leaves, remains unclear. Here, laboratory and semifield behavioral assays were used to test whether leaf volatiles enhance adult D. suzukii attraction and oviposition on blueberry fruit, followed by gas chromatography-mass spectrometry characterization of fruit and leaf VOCs and behavioral and electroantennographic (EAG) assays to assess responses to individual compounds. In laboratory trials, both sexes were significantly more attracted to fruit when leaves were present compared to fruit alone. Likewise, oviposition rates increased in the presence of leaves during cage choice experiments. Leaves were more fragrant than fruit on a per gram basis, emitting both a greater quantity and number of compounds. Among the VOCs emitted in greater amounts from the "fruit + leaf" treatment than from "fruit" alone, 9 compounds were examined, and 2-linalool and 6,10,14-trimethyl-2-pentadecanone-attracted females individually and in a blend and elicited strong EAG responses. These findings demonstrate that attraction is influenced by a combination of plant-derived cues; however, further field studies are needed to confirm these results under natural conditions. This knowledge advances our understanding of D. suzukii chemical ecology and may support the development of improved monitoring tools and behavior-based control strategies for this pest.