手性氟虫腈对意大利蜜蜂和稻螟赤眼蜂的急性毒性及安全评价

Acute Toxicities and Safety Evaluation of Chiral Fipronil to Apis mellifera L. and Trichogramma japonicum Ashmead

手性农药多以外消旋体形式用于农业生产和卫生害虫防治中。但手性农药对映体通常具有不同的生物活性和毒性,这种现象在农药环境风险评价过程中往往被忽视。本研究以氟虫腈为例,首先用高效液相色谱-手性固定相(HPLC-CSP)技术拆分出氟虫腈的S型和R型2种对映体,分别采用点滴法和药膜法测定了氟虫腈对映体及外消旋体对意大利蜜蜂(Apis mellifera L.)和稻螟赤眼蜂(Trichogramma japonicum Ashmead)的急性毒性。结果显示,S(+)-氟虫腈、R(-)-氟虫腈和外消旋体对意大利蜜蜂的48h-LD50分别为0.00341、0.00396和0.00383μg·蜂-1,对稻螟赤眼蜂的24h-LR50分别为7.56×10-7、8.06×10-7和7.29×10-7mg·cm-2。研究表明,氟虫腈对意大利蜜蜂具有高毒性风险,对稻螟赤眼蜂有极高毒性风险,且氟虫腈对意大利蜜蜂和稻螟赤眼蜂的急性毒性无明显的对映体选择性。因此,使用氟虫腈单一对映体不会降低其对环境生物的毒害风险。

Abstract： Most of the chiral pesticides were used as racemic forms in agricultural production and heakh pest control. However, differences existed in the biological activity and toxicity of the enantiomers of chiral pesti- cides, and the phenomena were usually ignored during the process of environmental risk evaluation of chiral pesticides. In this study, fipronil was selected as a model chiral pesticide, and its two enantiomers were isola- ted using an HPLC chiral stationary phase method （HPLC-CSP）. The acute toxicities of S（ ＋）-fipronil, R（-）- fipronil and racemic fipronil to Apis mellifera L. and Trichogrammajaponicum Ashmead were investigated by the standard drop method and drug membrane method. Results showed that the 48 h-LDs0 of S（ ＋ ）-fipronil, R（ - ）-fipronil and racemic fipronil to A. mellifera were 24 h-LRs0 of S（ ＋ ）-fipronil, R（ - ）-fipronil and racemic 0.00341,0.00396 and 0.00383 μg＇bee 1 respectively. The fipronil to T. japonicum were 7.56 x 10-7, 8.06 ×10-7 and7.29 x 10 7 mg·cm 2, respectively. It is demonstrated that fipronil was highly toxic to A. mellifera and very highly toxic to T. japonicum. No obvious differences in enantioselectivity were observed for acute toxicity of fipronil to A. mellifera and T. japonicum. Therefore, it is unlikely that the use of single enantiomer of fipronil would reduce the toxic risk to environmental organisms.