A 2-component blend of coconut oil derived fatty acids as an oviposition deterrent against Drosophila suzukii

Authors: ROH, GWANG HYUN - Oak Ridge Institute For Science And Education (ORISE); MEIER, LINNEA - Cornell University; SHRESTHA, BINITA - Cornell University; HESLER, STEPHEN - Cornell University; Kendra, Paul; Zhu, Junwei - Jerry; LOEB, GREGORY - Cornell University; TAY, JIA-WEI - University Of Hawaii; Cha, Dong

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: Spotted wing drosophila (SWD) is a serious invasive pest of berries and cherries worldwide. Insecticides are currently the primary strategy for managing SWD damage. It is imperative to develop alternative management approaches such as behavioral control. Researchers at USDA-ARS, APHIS-PPQ, Cornell University, and University of Hawaii have identified a mixture of two coconut-oil derived fatty acids as novel oviposition deterrent for SWD. In a series of laboratory and field tests, when directly applied on surface of raspberries, the 2-comonent mixture significantly reduced SWD oviposition in raspberries. These compounds are generally regarded as safe and has great potential as a novel management tool to control SWD damage in susceptible crops through behavioral manipulation.

Technical Abstract: Coconut free fatty acid (CFFA), a mixture of eight fatty acids derived from coconut oil, is an effective repellent and deterrent against a broad array of hematophagous insects. In this study, we evaluated the oviposition deterrent activity of CFFA on spotted wing drosophila (SWD; Drosophila suzukii), a destructive invasive pest of berries and cherries, and identified bioactive key-deterrent compounds. In laboratory two-choice tests, CFFA deterred SWD oviposition in a dose-dependent manner with the greatest reduction (99%) observed at a 20 mg dose compared to solvent control. In a field test, raspberries treated with 20 mg CFFA received 64% fewer SWD eggs than raspberries treated with the solvent control. In subsequent laboratory bioassays, two of CFFA components, caprylic and capric acids, significantly reduced SWD oviposition by themselves, while six other components had no effect. In choice and no-choice assays, we found that a blend of caprylic acid and capric acid, at equivalent concentrations and ratio as in CFFA, was as effective as CFFA, while caprylic acid or capric acid individually were not as effective as the 2-component blend or CFFA at equivalent concentrations, indicating the two compounds as the key oviposition deterrent components for SWD. The blend was also as effective as CFFA for other non-target drosophilid species in the field. The discovery of the effectiveness of CFFA compounds on multiple fruit fly species supports the potential broad efficacy of CFFA compounds against frugivorous insects. Given that CFFA compounds are generally regarded as safe to humans, CFFA and its bioactive components have potential application in sustainably reducing SWD damage in commercial fruit operations, thereby reducing the sole reliance on insecticides.