茶园花期用药后蜂花粉中吡虫啉及其代谢物残留的蜜蜂风险评估

Residues of imidacloprid and its metabolites in pollen, and exposure assessment for honey bees after spray application during the flowering period of tea

为研究茶花蜂花粉中吡虫啉及其代谢物残留对蜜蜂安全的影响,在茶树始花期喷施10%吡虫啉可湿性粉剂,测定防虫网大棚内茶花蜂花粉样品中吡虫啉及其代谢物吡虫啉烯烃、吡虫啉脲、6-氯烟酸的残留量,并结合现有毒理学数据和风险评估模型进行评估。结果表明:以风险商值(Risk Quotient,RQsp)进行初级风险评估时,吡虫啉在茶树上的使用对蜜蜂具有不可接受的急性接触风险;以暴露量/毒性(Exposure toxicity ratio,ETR)进行暴露评估时,蜜蜂急性经口风险可接受,而成蜂致畸风险在药后13 d内均不可接受。此外,ETR的评价结果还表明,吡虫啉对蜜蜂风险主要源于吡虫啉母体,代谢物的风险占比低于2%。基于风险评价结果以及本实验的局限性,对吡虫啉在茶树上的实际使用风险仍需开展进一步试验。

In order to assess the risk of imidacloprid exposure to honey bees, a wettable powder with 10% imidacloprid active ingredient was sprayed during the tea flowering period in a greenhouse covered with fly net. Residues of imidacloprid and its metabolites were detected in bee pollens, and an exposure assessment was carried out. The risk quotient of spray application（RQsp）showed that the acute contact risk was unacceptable. The exposure toxicity ratios（ETRs）showed that the risk of adult chronic exposure was also unacceptable for residues in pollen collected during 0 -13 days after application, while the acute oral risk was acceptable. Moreover, it was observed that the risk after imidacloprid application was mainly due to the parent residue, while its metabolites accounted for less than 2% of the overall risk. Based on the assessment results and the limitations of the present experiment, further trials are necessary to more precisely understand the risk to honey bees of imidacloprid application on tea.