Department of Entomology, University of Maryland, College Park, College Park, MD.
J Econ Entomol. 2020 Dec 9;113(6):2820-2831. doi: 10.1093/jee/toaa237.
Spray coverage may influence the efficacy of insecticides targeting the invasive vinegar fly Drosophila suzukii (Matsumura), a primary pest of raspberries and blackberries. In commercially managed caneberries, spray coverage is typically lowest in the inner and lower plant canopy, regions that overlap with higher levels of adult D. suzukii activity. To understand how spray coverage of fruit impacts efficacy against D. suzukii, laboratory bioassays were conducted using raspberries. In laboratory bioassays, higher spray coverage did not impact larval infestation rates but did increase adult mortality, indicating that flies can avoid a lethal dose of insecticide when applications do not achieve adequate coverage. We also evaluated how carrier water volume impacts spray coverage patterns throughout the canopy of raspberry and blackberry plants using both airblast and CO2 backpack sprayers. Increasing carrier water volume generally improved spray coverage in the lower plant canopy. However, effects in the upper plant canopy were inconsistent and varied between sprayer types. In addition to carrier water volume, other approaches, including adjusting the pesticide sprayer equipment used and/or sprayer calibration, should also be explored to improve coverage. Growers should evaluate spray coverage in their caneberries to identify and troubleshoot coverage issues. Results from this study indicate that taking the time to optimize this aspect of pesticide application may improve chemical management of D. suzukii and will likely also improve control of other important caneberry pests.
喷雾覆盖范围可能会影响针对入侵性果蝇 Drosophila suzukii（松田果蝇）的杀虫剂的效果，Drosophila suzukii 是覆盆子和黑莓的主要害虫。在商业管理的藤本浆果中，喷雾覆盖范围通常在植物内冠和下部最低，这些区域与成虫 Drosophila suzukii 活动水平较高的区域重叠。为了了解水果的喷雾覆盖范围如何影响对 Drosophila suzukii 的防治效果，我们使用覆盆子进行了实验室生物测定。在实验室生物测定中，较高的喷雾覆盖范围不会影响幼虫侵染率，但会增加成虫死亡率，这表明当施药无法达到足够的覆盖范围时，果蝇可以避免致命剂量的杀虫剂。我们还评估了使用空气喷枪和 CO2 背负式喷雾器时，载体水体积如何影响覆盆子和黑莓植物冠层内的喷雾覆盖模式。增加载体水体积通常会改善下部植物冠层的喷雾覆盖范围。然而，上部植物冠层的效果不一致，并且在喷雾器类型之间存在差异。除了载体水体积外，还应探索其他方法，包括调整农药喷雾器设备和/或喷雾器校准，以提高覆盖范围。种植者应评估藤本浆果中的喷雾覆盖范围，以识别和解决覆盖范围问题。本研究的结果表明，花时间优化农药应用的这一方面可能会改善 Drosophila suzukii 的化学管理，并且还可能改善对其他重要藤本浆果害虫的控制。
