Fruit Damage Alters Headspace Volatile Chemistry and Host Attraction in Drosophila suzukii.

Spotted-wing drosophila, Drosophila suzukii (Diptera: Drosophilidae), is a destructive pest of ripening berries and stone fruits. D. suzukii is attracted to ripening fruit volatiles, allowing it to occupy a distinct ecological niche from other Drosophila species. Ripening fruit volatiles act as relatively specific cues, which can be leveraged for pest management. Here, we tested whether volatiles from damaged host fruit serve as attractive adult host-finding cues. Using multivariate analysis, we characterized the headspace of mechanically damaged or undamaged blueberries and strawberries, finding distinct volatile organic chemical profiles. In no-choice assays, D. suzukii adults responded similarly between damaged and undamaged treatments at 24 and 48 h; however, when presented with a choice, adults were more strongly attracted to damaged than undamaged fruit volatiles. Adults exhibited a preference for volatiles from an individual damaged fruit over those from many undamaged fruit, despite higher total volatile release by the undamaged treatment as quantified by chromatography. In oviposition assays, females held in constant darkness laid significantly more eggs on damaged than undamaged fruit, whereas those exposed to a light cycle showed no preference. Infestation by early-instar D. suzukii induced a volatile profile distinct from mechanical damage, which attracted females but not males. Together, these results suggest that adult D. suzukii exhibit a preference for the specific ratio of volatiles from mechanically damaged fruit, while additional sensory inputs likely modulate subsequent behavioral decisions. Practically, damaged fruit volatile profiles identified here provide a chemical basis for developing more attractive lures to improve D. suzukii control and monitoring.