An IPM strategy to control spotted-wing drosophila in blueberry with natural repellents

The invasive Drosophila suzukii, a fruit fly also known as the spotted-wing drosophila (SWD), is a scourge on farmers as it attacks a wide variety of soft, thin-skinned fruits such as raspberries, blackberries, strawberries, grapes, and blueberries. They are native to Southeast Asia and were first detected in North America in Santa Cruz County, California, and Europe separately in 2008. In our field tests, we used a push-pull Integrated Pest Management (IPM) strategy to repel SWD from blueberries and attract them into baited traps. The repellent is methyl benzoate (MB), a naturally occurring volatile organic compound documented as a natural pesticide effective against SWD larvae and eggs. For use in the field, MB dispensers were constructed with 8 mL of MB saturated in felt, sealed in polyethylene tubing, and hung within the blueberry bushes. The attractants are a previously developed and tested blend of attractive compounds contained in baited traps holding drowning solution. On a weekly basis, we visited the blueberry fields to sample blueberries from rows that had one of four treatments: push-only, pull-only, and push-pull, and the control. We also collected and analyzed trap catches weekly to monitor the SWD population throughout the season. We determined that the presence of MB led to fewer eggs in infested blueberries, but the overall rate blueberry infestation remained unchanged. This year, the amount of MB will be increased to see if the rate of blueberry infestation by SWD can be reduced in the field.