Comparing the Efficacy of Season Long Management Programs Against Spotted Wing Drosophila in Blueberries

Spotted wing drosophila (SWD), <i>Drosophila suzukii<i>, is an invasive insect pest that has recently had a major impact on small fruit production throughout the United States. Due to the significant economic impact, growers have very low tolerance for this pest.  Currently management practices rely primarily on frequent applications of insecticides. It is therefore very important for the growers to have specific information on the efficacy and residual activity of insecticides against SWD.  We conducted field studies in highbush and rabbiteye blueberries to evaluate currently registered as well as new products.  We applied insecticides using an airblast sprayer and collected fruit and foliage samples one, three, and seven days after treatment. We set up semi-field bioassays using 32 ounce plastic cups.  Flies from our laboratory colony were exposed to the field treated fruit and foliage, and mortality was assessed after five days of exposure. Most chemicals were effective until three days, however residual efficacy of phosmet, zeta-cypermethrin, and fenpropathrin lasted for up to seven days.  These results show that there are several effective materials that growers can incorporate into SWD management programs to protect fruit from SWD infestation, but the retreatment intervals will vary depending on the particular chemicals being used.