Efficacy of entomopathogenic fungal products for biological control of spotted wing drosophila (Diptera: Drosophilidae) under laboratory conditions

Spotted wing drosophila, Drosophila suzukii Matsumura (Diptera: Drosophilidae), is a major pest of bushberries, caneberries, and other thin-skinned fruits around the world. Current control programs rely solely on the use of frequent insecticide applications. Entomopathogenic fungi have shown some efficacy for tephritid fruit flies and D. suzukii. In this study, formulated products BotaniGard ES (Beauveria bassiana), and PFR-97 20% WDG (Isaria fumosorosea) were evaluated for efficacy on adult D. suzukii in laboratory fruit-dip studies. Blueberry fruits were dipped in high and low label rates of each fungal suspension before exposure to D. suzukii. Mortality was assessed at 24, 48, 72, and 168 h (1 wk) after D. suzukii release. After 1 wk exposure, the remaining live flies, dead flies, and fruit were removed from containers. The live flies were discarded whereas dead flies were placed in separate containers and checked for mycosis after 1 wk. Fruits were placed in small solo cups with lids and checked after 2 wk for emergence of D. suzukii. The high rate of BotaniGard ES caused significant mortality after 24 h and both rates of BotaniGard ES reduced emergence from fruit compared with the control. BotaniGard ES may be useful in rotation with other effective compounds, but further research under field conditions is needed to confirm this finding.