Factors affecting the efficacy of attracticidal spheres for management of Drosophila suzukii (Diptera Drosophilidae)

Authors: NIXON, LAURA - Oak Ridge Institute For Science And Education (ORISE); CLOONAN, KEVIN - Trece, Inc; Rugh, Anthony; Jones, Sharon; Evans, Breyn; RICE, KEVIN - University Of Missouri; KIRKPATRICK, DANIELLE - Trece, Inc; SHORT, BRENT - Trece, Inc; RODRIGUEZ-SAONA, CESAR - Rutgers University; Leskey, Tracy

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2021
Publication Date: 12/7/2021
Citation: Nixon, L.J., Cloonan, K., Rugh, A.D., Jones, S.K., Evans, B.E., Rice, K., Kirkpatrick, D., Short, B., Rodriguez-Saona, C., Leskey, T.C. 2021. Factors affecting the efficacy of attracticidal spheres for management of Drosophila suzukii (Diptera Drosophilidae). Journal of Applied Entomology. 146(3):243-251. https://doi.org/10.1111/jen.12961.
DOI: https://doi.org/10.1111/jen.12961

Interpretive Summary: Spotted wing Drosophila is an invasive fruit fly which lays its eggs in a variety of small fruits, such as raspberries and blueberries, causing economic loss for growers. Visually attractive plastic red spheres with caps containing sugar and insecticide have previously been shown to effectively attract and kill spotted wing Drosophila. Here, we found that the sphere caps can be produced and stored for up to 12 months without losing toxicity; however, deployment of these spheres in field plots for more than six weeks results in a sharp decrease in toxicity, indicating they may need to be replaced at or before this time point. Spheres placed in raspberry and blueberry plants were effective at protecting the plants from spotted wing Drosophila at low and medium fly densities but were not effective at high fly densities.

Technical Abstract: Spotted wing Drosophila, Drosophila suzukii Matsumura, is an invasive pest in the United States, Europe, and South America. Females are able to oviposit in intact soft-skinned fruit, resulting in significant economic losses due to larval feeding. Attracticidal spheres, originally developed for the apple maggot, Rhagoletis pomonella (Walsh), have been used as a management tool for D. suzukii in a few studies, but little is known about their longevity as a killing device and their performance under varying pest densities. Here, we evaluated the efficacy of attracticidal spheres, containing 1% spinetoram, when stored for six and 12 months, and when deployed to manage low (four adults/plant), moderate (16 adults/plant), and high (64 adults/plant) density populations in blueberry and raspberry plants. Additionally, the effects of simulated (rainfall, sunlight, and rainfall/sunlight combinations) and field-based weathering for periods of six and 12 weeks on attracticidal spheres containing 1% thiamethoxam, fenpropathrin, spinetoram, methomyl, spinosad, dinotefuran, and lambda-cyhalothrin were evaluated. Sphere caps stored for up to 12 months yielded no significant decrease in mortality of exposed flies compared with spheres fitted with newly produced caps. For both raspberries and blueberries protected by 1% spinetoram attracticidal spheres, high relative densities of D. suzukii yielded significantly greater levels of infestation compared with moderate or low relative densities. Simulated and field-based weathering yielded reduced fly mortality for most insecticide materials, indicating that spheres may need to be replaced at six weeks or less to maximize their efficacy. In general, attracticidal spheres can assist in the management of D. suzukii but likely will not serve as a stand-alone tool, particularly under high pest densities.