手性乙虫腈对3种非靶标生物的急性毒性及初步风险评价

Acute toxicities and preliminary risk evaluation of chiral ethiprole to three non-target organisms

乙虫腈作为氟虫腈的替代药剂已在我国登记并推广使用,但其对环境有益生物的毒性研究鲜有报道。本研究分别采用点滴法、食下毒叶法和滤纸法测定了乙虫腈外消旋体及两个对映单体对意大利蜜蜂Apis mellifera L.、家蚕Bombyx mori和蚯蚓Eisenia foetida的急性毒性,并进行了初步风险评价。结果显示:乙虫腈外消旋体及其S-(+)-乙虫腈和R-(-)-乙虫腈单体对意大利蜜蜂的48 h-LD_(50)值分别为0.018 7、0.018 1和0.018 8μg/bee,对家蚕的96 h-LC50值分别为66.9、63.7和70.3 mg/L,对蚯蚓的48 h-LR_(50)值分别为511、488和547μg/cm^2。研究表明,乙虫腈对意大利蜜蜂具有高风险性,对家蚕为中等毒性,对蚯蚓毒性较低,田间施用时应防止药剂漂移至周围桑园对桑叶造成污染,并应避免在作物花期施药。此外,由于乙虫腈对供试3种非靶标生物的急性毒性均未表现出显著的对映体选择性差异,故无法通过对映单体的应用来降低其对蜜蜂、家蚕和蚯蚓的毒性及风险。

Ethiprole has been registered as an alternative pesticide of fipronil and widely promoted in China, but its toxicity to environmentally beneficial organisms has rarely been reported. In this study,the acute toxicities of racemic ethiprole and the corresponding enantiomers to Apis mellifera L., Bombyx mori and Eisenia foetida were investigated by the standard topical application method, intake poisonous leaf method and filter paper residue method, and the preliminary risk evaluation was carried out. Results showed that the 48 h-LD50 of racemic ethiprole, S-（＋）-ethiprole and R-（-）-ethiprole to A. mellifera were0.018 7, 0.018 1 and 0.018 8 μg/bee, respectively. The 96 h-LC50 of racemic ethiprole, S-（＋）-ethiprole and R-（-）-ethiprole to B. mori were 66.9, 63.7 and 70.3 mg/L, respectively. And the 48 h-LR50 of racemic ethiprole, S-（＋）-ethiprole and R-（-）-ethiprole to E. foetida were 511, 488 and 547 μg/cm2,respectively. The study showed that ethiprole was of high risk to A. mellifera, pollution. It should be avoided to apply the pesticide during the flowering period. Besides, no obvious enantio-selectivity was observed for acute toxicity to these three kinds of non-target organisms. So it is impossible to reduce the risks to bees, silkworms and earthworm by the application of the corresponding single enantiomer.