Palmitic and Stearic Acids Increase Oviposition Behavior and Residence Time As Contact-Based Arrestants in Drosophila Suzukii (diptera: Drosophilidae).

Drosophila suzukii (Matsumura), known as spotted-wing drosophila, is an invasive fruit fly that lays their eggs in soft-skinned fruits with its serrated ovipositor. In this study, we evaluated the effects of oviposition and residence behavior of D. suzukii by two saturated fatty acids (FAs): palmitic acid (C16:0) and stearic acid (C18:0). Both FAs were identified from a novel D. suzukii attractant, Decoy Attract and Kill, using gas chromatography-mass spectrometry and liquid chromatography-high resolution mass spectrometry. The FAs were then tested for their potential to alter oviposition in laboratory trials on blueberry with different concentrations and ratios to determine the optimal behavioral effects. We examined whether exposure to these FAs increased post-contact residence time and altered oviposition behavior. Exposure to 6.62 mg/L C16:0 and 3.61 mg/L C18:0 showed the strongest contact-mediated arrestment, resulting in increased oviposition on FA-treated blueberries. Females exposed to a 2:1 ratio of C16:0:C18:0 showed the greatest contact-dependent arrestment, followed by the 1:1 ratio, C16:0, and C18:0 alone. Additionally, we confirmed that both FAs act in a contact-dependent manner, increasing oviposition behavior after landing. Both C16:0 and C18:0 are effective contact-based arrestants that have the potential to protect soft-skinned fruits from D. suzukii oviposition damage.