Alternative pesticide application strategies for spotted wing Drosophila (Drosophila suzukii) management

Spotted Wing Drosophila (SWD) is a new invasive pest that is capable of causing major economic losses in berry and stone fruit crops in West Coast production areas. In 2009, reports of yield losses due to SWD were as high as 80% in this region. Adult flies lay eggs in ripening fruit and develop into larvae that feed on fruit making it unmarketable.

SWD was first recorded in 2008, and growers subsequently minimized crop losses by repeated full-cover applications of broad-spectrum pesticides. These practices significantly increased production costs and subsequently disrupted existing IPM programs. The current body of knowledge regarding SWD management is limited due to its recent arrival (2008-2010) and rapid colonization and dispersal. These pesticide sprays are not sustainable and dramatically increase production costs. Solutions to reduce pesticide use are needed and may include techniques such as border or alternate row sprays. These strategies are however not proven to control SWD. These alternative spray strategies previously resulted in higher beneficial insect populations than full-cover sprays and resulted in suppressing common pests.

In this study we are investigating these strategies on susceptible blueberries and raspberries. Additionally, we are assessing the impact of these alternative spray strategies on key non-target organisms. If effective, growers implementing these alternative application strategies for SWD management will reduce chemical use, levels of pesticide residue and risks to natural resources and the environment. Results from the 2011 field season will be presented.