Odors from the fungal pathogen Colletotrichum fioriniae repel Drosophila suzukii

To reduce insecticide reliance and use, alternative methods are needed for control of spotted-wing drosophila (Drosophila suzukii), which is a serious pest of soft, thin-skinned fruits. Previous research demonstrated that D. suzukii adults use odor cues to avoid blueberries infected with the fungal pathogen Colletotrichum fioriniae, which causes the disease anthracnose. To discover new repellents that can be deployed in push-pull systems, we investigated the odors of infected blueberry and tested the differentially induced volatiles on D. suzukii adult behavior. Volatile emission was similar between all five C. fioriniae strains tested. In total, 14 volatiles were found to be more abundant in the headspace of infected versus uninfected fruit. In multiple-choice bioassays with adults, nine volatiles elicited repellency responses, two acted as attractants, and three had neutral effect. Repellency of the nine volatiles was further evaluated in dual choice assays where all nine reduced fly capture by 43–96% compared to the control. The most repellent compounds tested were six carbon esters ethyl butanoate and ethyl (E)-but-2-enoate, which were more or equally repellent to the known D. suzukii repellents geosmin, 1-conten-3-ol, and 2-pentylfuran. Additionally, styrene was identified as a potential attractant for this insect. These volatiles may be useful semiochemicals for manipulation of D. suzukii behavior for crop protection.