Octabor (boron) as a Low Toxicity Control Tactic for the Spotted Wing Drosophila, Drosophila suzukii (Matsumura)

Abstract

The recently introduced spotted wing drosophila is one of the most serious pests in small fruit production in the United States and Europe. Most control relies upon multiple applications of synthetic insecticides. In an effort to find less-toxic insecticides to consumers, farm workers, and wildlife, we conducted two laboratory trials and a semi-field trial in order to assess the potential for disodium octaborate tetrahydrateformulated and sold as Octabor®(U.S. Borax, Inc.) as a control for spotted wing drosophila in wild blueberry. We found that Octabor at 0.6 and 1.0% (w/v) applied to wild blueberry fruit resulted in higher mortality of flies than non-treated control fruit. Addition of sugar to Octabor enhanced mortality in one of the two trials, with an interaction between sugar addition and Octabor rate suggesting that the addition of sugar provided the greatest enhancement at the low rate. Our semi-field study showed that an apparent repellency effect of Octabor provided protection of fruit from infestation for up to 3 days. Also in the semi-field study, we observed a delayed effect on fly mortality. Increased fly mortality occurred over time, relative to the non-treated control fruit. The greatest fly mortality, relative to the non-treated control, resulted from flies being exposed to fruit treated 3 and 7 days prior to fly exposure, but not immediately after the treatment of Octabor. We speculate on why this type of delay in mortality might have occurred.