氟虫腈对家蚕的急性毒性与安全评价研究

氟虫腈是我国稻桑混栽地区水稻上普遍使用的杀虫剂。采用食下毒叶法、口器注入法与药 膜法测定了不同条件下氟虫腈对家蚕的急性毒性。氟虫腈对2龄、3龄、4龄、5龄家蚕的摄入LC50值 (48 h,下同)分别为4.89、6.46、9.47、11.59 mg/L;对5龄家蚕的LD50值为1.38 μg/蚕;在25、30、35 ℃ 3个温度下,氟虫腈对2龄家蚕的LC50值分别为4.81、4.59、2.05 mg/L;桑叶浸药时间为1 s、10 s、1 min、10 min、1 h时,氟虫腈对3龄家蚕的LC50值分别为9.12、6.46、4.39、3.68、2.80 mg/L;家蚕在氟虫腈药膜上爬行1、10、30、60 min后, 对4龄家蚕的接触LC50值分别为2.82、2.35、2.05、1.57 μg/cm2。研究表明,胃毒是氟虫腈对家蚕的主要作用方式,氟虫腈在桑园附近水稻上使用对家蚕有较大风险。

Acute Toxicity and Safety Evaluation of Fipronil to Bombyx mori

Fipronil is one of the insecticides popularly used in paddy rice and mulberry mix-cultivation area in China. Toxicity of fipronil to silkworm(Bombyx mori) in different situations were conducted by methods of feeding toxic mulberry leaves and injecting into the mouthparts, and methods of contacting with toxic membrane, respectively. For the second,third,fourth and fifth-instar larvae, the LC50 value(48 h) of fipronil to silkworm was 4.89,6.46,9.47 and 11.59 mg/L,respectively. The LD50 value for fifth instar was 1.38 μg/silkworm. When environmental temperature was 25℃,30℃ and 35℃, the LC50 value (48 h) to the second-instar larvae was 4.81,4.59 and 2.05 mg/L, respectively. When immersion time of mulberry leaves in fipronil solution was 1 s,10 s,1 min,10 min and 1 h, the LC50 value (48 h) to the third-instar larvae was 9.12,6.46,4.39,3.68 and 2.80 mg/L, respectively.After contact of silkworm with filter paper treated by fipronil solution in time of 1,10,30 and 60 min, the LC50 value (48 h) to the fourth-instar larvae was 2.82,2.35,2.05 and 1.57 μg/cm2 ,respectively.The results indicated that the toxicity of fipronil to silkworm is caused mainly by mode of feeding and the risk of fipronil to silkworm is relatively high when fipronil is used near mulberry cultivation area.