Lethal and sublethal effects of pesticides used in Brazilian citrus groves on Panonychus citri (Acari: Tetranychidae)

ABSTRACT: Pesticides have been blamed as the principal factor responsible for biological disequilibrium favoring the population increase of Panonychus citri (McGregor) in Brazilian citrus groves. In order to generate subsidies for the integrated management of this pest, we evaluated the lethal and sublethal effects of pesticides used in citrus on P. citri. We tested 18 pesticides by evaluating mortality of adult female, egg viability and adult avoidance. For imidacloprid, pyriproxyfen, dimethoate, deltamethrin, lambda-cyhalothrin and lime sulfur, the principal insecticides used in Brazilian orchards, the oviposition behavior and the incidence of adult females on discontinuous pesticide residues were evaluated. The pesticides which caused adult P. citri mortality were: abamectin (94%), dimethoate (86%), lime sulfur (69%), fenpropathrin (44%), diafenthiuron (25%) and lambda-cyhalothrin (23%). The pesticides affecting egg viability were: fenpropathrin (53%), dimethoate (30%) and lime sulfur (22%). Fenpropathrin, lambda-cyhalothrin and lime sulfur caused repellent effects of 55, 45 and 22%, respectively. P. citri preferred areas untreated with deltamethrin, lambda-cyhalothrin and lime sulfur for oviposition and permanence, but the species could not distinguish areas treated with imidacloprid, pyriproxyfen and dimethoate. The insecticides abamectin, dimethoate and diafenthiuron affected survival and did not cause changes in P. citri behavior. These pesticides should be used mainly in periods P. citri occurs. On the other hand, fenpropathrin, lambda-cyhalothrin, lime sulfur and deltamethrin affect dispersal behavior, oviposition and P. citri incidence and their use should be avoided.摘要：农药被认为是引发巴西柑橘园生物失衡、进而导致柑橘全爪螨（Panonychus citri (McGregor)）种群数量攀升的核心因素。为给该害虫的综合治理提供支撑依据，本研究评估了柑橘种植中常用农药对柑橘全爪螨的致死与亚致死效应。我们通过检测雌成虫死亡率、卵孵化活力以及成虫趋避行为，共测试了18种农药；针对巴西果园中主流使用的6种杀虫剂——吡虫啉（imidacloprid）、吡丙醚（pyriproxyfen）、乐果（dimethoate）、溴氰菊酯（deltamethrin）、氯氟氰菊酯（lambda-cyhalothrin）与石硫合剂（lime sulfur），我们进一步评估了其产卵行为以及成虫在间断性农药残留环境下的栖息选择情况。可导致柑橘全爪螨雌成虫死亡的农药包括：阿维菌素（abamectin，94%）、乐果（86%）、石硫合剂（69%）、甲氰菊酯（fenpropathrin，44%）、丁醚脲（diafenthiuron，25%）以及氯氟氰菊酯（23%）；影响卵孵化活力的农药包括：甲氰菊酯（53%）、乐果（30%）与石硫合剂（22%）。甲氰菊酯、氯氟氰菊酯与石硫合剂分别产生了55%、45%与22%的驱避效应。柑橘全爪螨偏好选择未喷施溴氰菊酯、氯氟氰菊酯与石硫合剂的区域进行产卵与栖息，但无法区分喷施吡虫啉、吡丙醚与乐果的区域。阿维菌素、乐果与丁醚脲仅对柑橘全爪螨的存活产生影响，未改变其行为模式，此类农药可主要在该螨发生时期施用；反之，甲氰菊酯、氯氟氰菊酯、石硫合剂与溴氰菊酯会影响柑橘全爪螨的扩散行为、产卵行为与种群发生量，应避免使用。