Spotted Wing Drosophila: A Major Threat to Small and Stone Fruit Production in the United States

Spotted wing drosophila (SWD), Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), a native of Eastern and Southeastern Asia, has recently emerged as a devastating pest of small and stone fruits in the US. Since its first detection in California in 2008, SWD has spread throughout the United States causing significant losses in crop yield (as high as 100%) and quality, which have been estimated at $850-900 million annually. The SWD is a highly polyphagous insect and presents a major threat to soft- and thin-skinned fruit industries including blueberries, caneberries (blackberries and raspberries), cherries, strawberries, peaches, and grapes in the US. Management of SWD is further complicated by the lack of reliable traps and lures that can be used to determine fly density and infestation risk. While this aspect of SWD monitoring is actively being researched, SWD management is currently achieved primarily through preventative insecticide applications. The zero tolerance policy for SWD by marketers has led growers to make weekly insecticide applications, which may be reapplied in the event of rain. With applications occurring once or twice a week throughout the growing season, the selection pressure is extreme and likely to lead to resistance development in SWD, which threatens the sustainability of SWD management programs.  Results from the recent investigations to optimize the use of currently available tools in SWD monitoring and management programs will be discussed.