Testing the effectiveness of floor cover and insecticide treatment program for spotted-wing drosophila, Drosophila suzukii, in highbush blueberries

Abstract

Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae), commonly referred to as spotted-wing drosophila, is an invasive fruit fly that arrived in the continental United States in 2008 (Turcotte et al. 2018). D. suzukii differs from typical fruit flies in that the females have serrated ovipositors, which enable female D. suzukii to saw through the flesh of unripe fruit to lay eggs underneath the skin of thin-skinned fruit such as raspberries, blueberries, cherries, and strawberries. The eggs hatch inside and mature while destroying the fruit. Due to this, growers will experience serious financial loss if the flies are not combated. The first objective of this study was to test the efficacy of current pesticide application methods as compared to methods that are “reduced-risk” to other insects and the environment. The second objective was to test how temperature and relative humidity affect egg-laying behavior and larval survival. Through the collection of blueberries infested by wild D. suzukii, and the artificial infestation of store-bought blueberries, the study found that “reduced-risk” insecticide application methods, that included pesticides more targeted to D. suzukii, and applied later in the season, are effective at controlling infestation until harvest. The study also found that, while differences in ground cover do not change the larval survival rates, the utilization of Mylar ground cover is more effective at deterring spotted-wing drosophila from laying eggs in blueberry cultivars than the utilization of woodchip ground cover due to Mylar’s ability to reflect both heat and light. Further studies are required to provide better insight into D. suzukii’s egg laying behavior and larval survival.