USDA-ARS, Temperate Tree Fruit and Vegetable Research Unit, Wapato, WA, 98951, USA.
Washington State University, 166 FSHN 100 Dairy Road, Pullman, WA, 99164, USA.
Exp Appl Acarol. 2021 Jun;84(2):407-418. doi: 10.1007/s10493-021-00621-7. Epub 2021 May 10.
Tetranychus urticae Koch (Acari: Tetranychidae), twospotted spider mite, is a major secondary pest of strawberry and can cause significant yield loss. Tetranychus urticae is typically controlled using miticides, which has led to rapid resistance development. In South Carolina (USA), extension agents and growers have reported field failures of miticides (inadequate pest suppression), but resistance has not been quantitatively determined. In 2018, we determined the level of miticide resistance of six T. urticae populations found on strawberry across South Carolina. We examined efficacy of all miticides registered for use on US strawberry by conducting an initial diagnostic bioassay at 20% of the maximum labeled field rate. Any population × active ingredient combination resulting in < 55% mortality was identified as 'potentially resistant' and concentration-response bioassays were then conducted to calculate LC values for an individual population. These values were compared with those of a known-susceptible laboratory population to calculate resistance ratios (RR). Our results indicate that examined South Carolina populations of T. urticae from strawberry were highly resistant to bifenthrin (RR = 100-60,000) and there was reduced susceptibility to fenbutatin-oxide (RR = 25-123). The 'Sardinia' population had decreased abamectin susceptibility (RR = 25). No resistance to hexythiazox, etoxazole, acequinocyl, bifenazate, fenpyroximate, spiromesifen, or cyflumetofen was found. Based on available data, it appears that miticide resistance is not a likely cause of field failures and issues related to application error and coverage should be investigated. Overall, this work supports the need to reduce the use of broad-spectrum pesticides and older products, in favor of newer miticide chemistries due to resistance issues.
二斑叶螨（Acari: Tetranychidae），又称两点叶螨，是草莓的主要次要害虫，可导致显著的产量损失。二斑叶螨通常使用杀螨剂进行控制，但这导致了抗药性的快速发展。在美国南卡罗来纳州，推广代理和种植者报告了杀螨剂在田间的失效（防治效果不足），但尚未对其进行定量测定。2018 年，我们测定了在南卡罗来纳州草莓上发现的六个二斑叶螨种群的杀螨剂抗药性水平。我们通过在最大标签田间用量的 20%下进行初始诊断生物测定，检查了所有在美国草莓上注册使用的杀螨剂的功效。任何死亡率<55%的种群×活性成分组合被鉴定为“可能具有抗性”，然后进行浓度-反应生物测定，以计算单个种群的 LC 值。将这些值与已知敏感的实验室种群进行比较，以计算抗性比（RR）。我们的研究结果表明，在南卡罗来纳州草莓上检测到的二斑叶螨种群对高效氯氟氰菊酯（RR=100-60000）具有高度抗性，对丁硫克百威的敏感性降低（RR=25-123）。“撒丁岛”种群对阿维菌素的敏感性降低（RR=25）。未发现对己唑醇、乙螨唑、螺虫乙酯、螺螨酯、甲氰菊酯、唑螨酯、噻虫嗪或氟吡呋喃酮的抗性。根据现有数据，田间失效似乎不是抗药性的原因，应调查与施药错误和覆盖率有关的问题。总的来说，这项工作支持减少广谱杀虫剂和旧产品使用的必要性，转而支持使用新的杀螨剂化学物质，因为存在抗药性问题。
