Partial Budget Analysis of Exclusion Netting and Organic- certified Insecticides for Management of Spotted-wing Drosophila (Diptera: Drosophilidae) on Small Farms in the Upper Midwest

Abstract

Drosophila suzukii Matsumura (Diptera: Drosophilidae), or spotted-wing drosophila, is an invasive pest first detected in the United States in 2008. Although D. suzukii can use many cultivated fruit as hosts, raspberries are considered ‘most at risk’ for infestation. Conventional broad-spectrum insecticides are proven effective D. suzukii controls and can be economically profitable when combined with integrated pest management (IPM) on large-scale commercial raspberry farms. It remains unclear, however, whether organic controls are cost-effective strategies, particularly for farms operating on a small-scale seasonal basis, as is common in the Upper Midwest. The purpose of this paper is to explore the efficacy of two organic D. suzukii controls— exclusion netting for high tunnels and organic insecticides for open plots using data available from different field trials—and to ascertain whether any economic benefits of the organic controls outweigh treatment costs for small-scale raspberry operations under different risk scenarios. The field trials suggest that the organic

treatments are effective controls for D. suzukii infestation and economically profitable. The exclusion net- ting treatment produced positive net returns compared to the alternative of no treatment and economically

outperformed the organic-certified insecticide treatment for several yield, price and infestation scenarios. As D. suzukii infestation rates increased, net returns improved for both organic treatments. The economic results were robust across a range of yields and prices, suggesting that in almost all scenarios small scale organic raspberry growers benefit economically from the application of exclusion netting on high tunnels and insecticides for open plots.