Department of Chemistry, Colorado State University, Fort Collins, CO, USA.
Department of Agricultural Biology, Colorado State University, Fort Collins, CO, USA.
Pest Manag Sci. 2021 Apr;77(4):1748-1756. doi: 10.1002/ps.6195. Epub 2020 Dec 24.
Citrus greening disease (Huanglongbing, HLB) has infected >90% of Florida's oranges and thus growers are desperate to improve pest management strategies. In this field study, insecticide application efficacy was investigated with liquid chromatography mass spectrometry to determine if insecticide concentration and distribution were effective at killing the target pest Asian citrus psyllids (ACP). Sample discs attached to leaves were sprayed with imidacloprid and malathion at a field site in Florida. Application method, canopy height and depth, cardinal side of tree, and leaf side were considered to assess the spatial distribution of insecticides throughout citrus trees. Furthermore, ACP were inspected before and after insecticide applications to quantify psyllid population response.
Our findings show that although insecticide concentrations were high enough to kill ACP, the spatial distribution of insecticides throughout individual trees was highly variable and live ACP were detected after insecticide application. The top side of leaves received significantly more insecticide than the underside of leaves. Additionally, inadequate distribution to different areas of the tree canopy was observed for all application methods tested (aerial, ground speed-sprayer, and ground side-sprayer). Inspections of ACP populations before and after insecticide applications resulted in reductions of 85% (malathion) and 48-80% (imidacloprid).
The variability in insecticide spatial distribution due to application method allows remaining ACP to continue spreading citrus greening disease to unprotected trees. Further research is needed to improve insecticide application methods and technology for citrus trees in order to implement effective pest management strategies and fully target ACP to eliminate HLB. © 2020 Society of Chemical Industry.
黄龙病已感染了佛罗里达州超过 90%的橙子，因此种植者迫切需要改进害虫管理策略。在这项田间研究中，采用液相色谱-质谱法研究了杀虫剂的应用效果，以确定杀虫剂的浓度和分布是否能有效杀死目标害虫亚洲柑橘木虱（ACP）。在佛罗里达州的一个田间地点，将附着在叶片上的样品圆盘用吡虫啉和马拉硫磷喷洒。考虑了施药方法、冠层高度和深度、树的方位和叶片侧，以评估杀虫剂在整个柑橘树上的空间分布。此外，在施药前后检查 ACP，以量化木虱种群的反应。
我们的研究结果表明，尽管杀虫剂的浓度足以杀死 ACP，但杀虫剂在单个树木中的空间分布差异很大，施药后仍能检测到活的 ACP。叶片的上表面比下表面接收的杀虫剂多。此外，所有测试的施药方法（空中、地面速度喷雾器和地面侧面喷雾器）都观察到树冠不同区域的分配不足。在施药前后检查 ACP 种群，结果表明马拉硫磷的减少率为 85%，吡虫啉的减少率为 48-80%。
由于施药方法的不同，杀虫剂的空间分布存在差异，这使得剩余的 ACP 能够继续传播柑橘黄龙病，感染未受保护的树木。需要进一步研究以改进柑橘树的杀虫剂施药方法和技术，以实施有效的害虫管理策略，并充分针对 ACP，以消除 HLB。© 2020 化学工业协会。
