噻虫嗪和噻虫胺对鸟类的急性毒性与风险评估

Toxicity and risk assessment of thiamethoxam and clothianidin on birds

【目的】明确噻虫嗪与噻虫胺 2 种新烟碱农药对鸟类的风险。【方法】采用经口灌胃法测定 98%噻虫嗪或噻虫胺原药、30%噻虫嗪或 20%噻虫胺悬浮剂、42%噻虫嗪或 46%噻虫胺种子处理悬浮剂对日本鹌鹑的毒性等级。根据供试农药对鸟类的毒性数据,结合田间用药信息,开展了 2 种农药对鸟类的初级风险评估。【结果】98%噻虫嗪原药、30%噻虫嗪悬浮剂和 42%噻虫嗪种子处理悬浮剂对日本鹌鹑的半致死剂量( 7 d-LD_(50)) 分别为 1500、481 和 266 mg·kg^(-1),毒性等级分别为低毒、中毒、中毒,悬浮剂和种子处理悬浮剂的毒性高于原药。98%噻虫胺原药、20%噻虫胺悬浮剂和 46%噻虫胺种子处理悬浮剂对日本鹌鹑的 7 d-LD_(50)分别为 369、397 和 1569 mg·kg^(-1),毒性等级分别为中毒、中毒和低毒,种子处理悬浮剂的毒性最低。噻虫嗪和噻虫胺的悬浮剂在水稻田间使用时,对鸟类急性、短期和长期暴露的风险商值均小于 1,风险可接受;噻虫嗪和噻虫胺的种子处理悬浮剂在玉米田应用时,对鸟类急性、短期和长期暴露的风险商值均大于 1,风险不可接受。【结论】噻虫嗪和噻虫胺的悬浮剂在田间应用时对鸟类相对安全,2 种农药的种子处理悬浮剂可能对鸟类产生危害。在种子处理场景中,播种后尽可能覆土或覆膜,减少种子直接暴露被鸟类取食;在鸟类保护区域,应避免使用噻虫嗪和噻虫胺的种子处理悬浮剂,以减轻农药施用对鸟类的危害。

【Aim】 This study aimed to verify the risks of two types of neonicotinoid pesticides,namely thiamethoxam and clothianidin,on birds.【Method】 Toxicity level of 98% thiamethoxam or clothianidin technical materials,30% thiamethoxam or 20% clothianidin suspension concentrate,and 42% thiamethoxam or 46% clothianidin suspension concentrate for seed treatment were tested on Coturnix japonica individuals using the transoral gavage method.Based on the toxicity data of tested pesticides to birds,combined with the field medication information.A primary risk assessment on the influence of the two types of pesticides on birds was carried out.【Result】 For C.japonica,the acute toxicity semi-lethal doses(7 d-LD_(50)) of 98% thiamethoxam technical materials,30% thiamethoxam suspension concentrate,and 42% thiamethoxam suspension concentrate for seed treatment were 1500,481,and 266 mg·kg^(-1)body weight,respectively,with toxicity levels being low,medium,and medium.The suspension concentrate and suspension concentrate for seed treatment were more toxic than the technical material.The acute toxicity semi-lethal doses(7 d-LD_(50)) of 98% clothianidin technical material,20% clothianidin suspension concentrate,and 46% clothianidin suspension concentrate for seed treatment were 369,397,and 1569 mg·kg^(-1)body weight,respectively,with toxicity levels being medium,medium,and low.The suspension concentrate for seed treatment had the lowest toxicity.When used in rice paddies,the risk quotients(RQ) of acute,short-term,and long-term exposure by birds to thiamethoxam and clothianidin suspension concentrates were less than 1(RQ<1),indicating that the level of risk was acceptable.When used in maize fields,the risk quotients of the acute,short-term,and long-term exposure by birds to thiamethoxam and clothianidin suspension concentrates for seed treatment were higher than 1(RQ>1),indicating that the risk was unacceptable.【Conclusion】 Both thiamethoxam and clothianidin suspension concentrates are relatively safe for birds when applied to crop fields,but the suspension concentrate for seed treatment of these two types of pesticides may be harmful to birds.Therefore,in the scenario of seed treatment,it is suggested that after sowing,seeds should be covered with soil or mulch as much as possible to reduce possible ingestion by birds.In the scenario of bird reserve areas,it is suggested that thiamethoxam and clothianidin suspension concentrates for seed treatment should be avoided to reduce the risk of harming birds through pesticide use.