吡虫啉在棉花上的残留消解动态及对意大利蜂的急性毒性

【目的】分析吡虫啉在棉花植株上的残留消解动态;测定在接触暴露途径下,吡虫啉对意大利蜜蜂的急性毒性。【方法】前处理采用改进的 QuEChERS 方法,用UPLC-MS测定吡虫啉在棉花叶片、花及土壤上的残留消解动态;采用点滴法测定吡虫啉对意大利蜜蜂的急性接触毒性。【结果】吡虫啉标样的峰面积(y)与浓度(x)呈线性关系,回归方程为y=4 010.25x+2 746.69,相关系数r为0.998 7,最低检测浓度LOQ为0.02 mg/kg。吡虫啉在棉花植株和土壤样品的添加回收率介于94.27%～101.63%,相对偏差率介于2.01%～3.85%,符合农药残留试验准则中对残留检测方法的要求。吡虫啉在棉花叶片、花及土壤的残留量半衰期分别是4.02、4.30和5.27 d,属于易降解农药。吡虫啉对意大利蜜蜂的急性毒性48 h LC₅₀为0.064 9μga.i./bee。【结论】吡虫啉对意大利蜂的急性接触毒性为高毒,应关注其在新疆棉田使用时对传粉昆虫及其他天敌的安全性。

Residues Degradation Dynamics of Imidacloprid in Cotton and Its Acute Toxicity to Apis mellifera

【Objective】 The aim of this project is to analyze the residual degradation dynamics of imidacloprid in cotton plants and determine the acute toxicity of imidacloprid to Italian honeybees under the exposure route. 【Methods】 The improved QuEChERS method was used in the pretreatment, and the residues degradation dynamics of imidacloprid in cotton leaves, flowers and soil were determined by UPLC-MS, and the acute contact toxicity of imidacloprid to Apis mellifera was determined by drop method. 【Results】 Imidacloprid was a linear relationship between the peak area (y) and the concentration (x). The regression equation was y=4,010.25x+2,746.69, the correlation coefficient r was 0.998,7, and the limit detection concentration (LOQ) was 0.02 mg/kg. The recovery rate of imidacloprid in cotton plant and soil samples was between 94.27% and 101.63%, and the relative deviation rate was between 2.01% and 3.85%. The half lives of imidacloprid in cotton leaves, flowers and soil were 4.02, 4.30 and 5.27 days, respectively, which were easily degradable pesticides. The acute toxicity of imidacloprid to Apis mellifera was 0.064,9 μg a.i./bee at 48 h. 【Conclusion】 the acute contact toxicity of imidacloprid to Apis mellifera is high toxicity, so the safety of imidacloprid to pollinating insects and more attention should be paid to other natural enemies.