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7种杀虫剂对异色瓢虫幼虫的毒力及安全性评价

Toxicity and safety evaluation of seven recommended insecticides against Harmonia axyridis (Pallas) in tobacco fields

  • 摘要: 为明确杀虫剂对异色瓢虫的影响,用滤纸接触法测定了7种烟田中推荐使用的杀虫剂对异色瓢虫3龄幼虫的毒力,通过计算安全系数来评估7种杀虫剂对异色瓢虫的影响。结果表明,2.5%高效氯氟氰菊酯,25 g/L溴氰菊酯及4.5%高效氯氰菊酯对异色瓢虫3龄幼虫的毒力较高,LC50值分别为0.39、0.43和5.89 mg/L。70%吡虫啉水分散粒剂对异色瓢虫LC50值为128.36 mg/L。3.2%阿维菌素、25%噻虫嗪和25%吡蚜酮对异色瓢虫的毒力较低,LC50值分别为363.39、391.22、1 074.20 mg/L。根据相对安全系数和绝对安全系数可知,25 g/L溴氰菊酯对异色瓢虫3龄幼虫的风险达到极高等级,2.5%高效氯氟氰菊酯介于高风险和极高风险之间,4.5%高效氯氰菊酯处于中等到高等风险范围,70%吡虫啉的风险性介于中等到低等之间,25%噻虫嗪、3.2%阿维菌素、25%吡蚜酮均处于低风险范围。因此,建议在烟田天敌数量较多时,优先选用对天敌相对安全的噻虫嗪、阿维菌素和吡蚜酮来防治烟草害虫。

     

    Abstract: To evaluate the effects of insecticides on Harmonia axyridis (Pallas), a filter paper contact method was adopted to detect the toxicity of seven recommended insecticides against H. axyridis in tobacco fields, and the effects of the seven insecticides on H. axyridis were evaluated by calculating their safety coefficients. The results showed that 2.5% cyhalothrin, 25 g/L deltamethrin and 4.5% beta cypermethrin had high toxicity to 3rd instar larvae of H. axyridis, and their LC50 values to H. axyridis were 0.39, 0.43 and 5.89 mg/L, respectively. The LC50 value of 70% imidacloprid was 128.36 mg/L. The toxicities of 3.2% abamectin, 25% thiamethoxam and 25% pymetrozine were lower to H. axyridis with the LC50 value of 363.39, 391.22 and 1 074.20 mg/L, respectively. Considering the relative and absolute safety factors, 25 g/L deltamethrin to 3rd instar larvae of H. axyridis reached an extra high risk level, 2.5% cyhalothrin was between high and extra high risk levels, and 4.5% cypermethrin was between middle and high risk levels. The risk level of 70% imidacloprid was between low and high, and those of 3.2% abamectin, 25% thiamethoxam and 25% pymetrozine were low. Therefore, when the population of natural enemies was higher, thiamethoxam, abamectin and pymetrozine are preferentially recommended for controlling pests in tobacco fields.

     

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