异丙甲草胺、醚菌酯和咪鲜胺锰盐对中华大蟾蜍蝌蚪的急性毒性效应

Acute Lethal Toxic Effects of Metolachlor, Kresoxim-methyl and Prochloraz-manganese Chloride Complex to the Chinese toad(Bufo gargarizans) Tadpoles

采用静态换水方法研究了异丙甲草胺、醚菌酯和咪鲜胺锰盐3种农药对中华大蟾蜍(Bufo gargarizans)蝌蚪的急性毒性及其联合毒性。结果表明,在急性毒性和两两联合毒性实验中,不同浓度农药对蝌蚪的死亡率影响均显著。在24 h、48 h及72 h急性毒性实验中,异丙甲草胺对中华大蟾蜍蝌蚪的半致死浓度(LC50)分别为29.81、28.81和25.83 mg/L,醚菌酯为1.72、1.46和1.41 mg/L,咪鲜胺锰盐为7.43、3.75和3.22 mg/L。异丙甲草胺、醚菌酯和咪鲜胺锰盐3种农药的安全浓度(SC)分别为8.07、0.32和0.29 mg/L。异丙甲草胺为中等毒性农药,而醚菌酯和咪鲜胺锰盐均为剧毒性农药。在两两联合的毒性实验中,异丙甲草胺﹣醚菌酯和异丙甲草胺﹣咪鲜胺锰盐均表现为中等毒性,醚菌酯﹣咪鲜胺锰盐表现为剧毒性。在24 h、48 h及72 h两两联合毒性实验中,异丙甲草胺﹣醚菌酯对中华大蟾蜍蝌蚪的半致死浓度(LC50)分别为18.41、15.69和13.38 mg/L,异丙甲草胺﹣咪鲜胺锰盐为15.56、10.45和8.11 mg/L,醚菌酯﹣咪鲜胺锰盐为4.17、2.84和2.00 mg/L,且其相对应的安全浓度分别为3.42、1.41和0.40 mg/L。在联合毒性评价中,异丙甲草胺﹣醚菌酯联合组在24 h和48 h表现为拮抗作用,醚菌酯﹣咪鲜胺锰盐联合组在48 h表现为加和作用,其余均表现为协同作用。同样,重复方差分析结果表明,农药浓度、染毒时间及两者相互作用对蝌蚪的存活率影响均显著。与前期发表数据进行比较,表明中华大蟾蜍蝌蚪对污染物具有很强的敏感性。这些结果将为无尾类动物的毒理学研究提供科学依据。

Acute and joint toxicity of three pesticides to an anuran species tadpoles was investigated. With the method of stability water tests, we examined the acute toxicity and their pair-wise joint toxicity of metolachlor, kresoxim-methyl and prochloraz-manganese chloride complex to the Chinese toad（Bufo gargarizans） tadpoles. Our results showed that the mortality of experimental tadpoles was significantly affected by treatment concentrations of both pesticide alone and their pair-wise combinations（Table 1, Table 3, One-way ANOVA, n = 10）. Under acute toxicity alone treatments examined at 24 h, 48 h and 72 h, the median lethal concentrations（LC50） of metolachlor were 29.81, 28.81 and 25.83 mg/L, respectively; the corresponding values for kresoxim-methyl were 1.72, 1.46 and 1.41 mg/L, and those, for prochloraz-manganese chloride complex were 7.43, 3.75 and 3.22 mg/L, respectively. The safety concentration（SC） of metolachlor, kresoxim-methyl and prochloraz-manganese chloride complex were 8.07, 0.32 and 0.29 mg/L, respectively（Table 2）. The metolachlor was moderately toxic, whereas both kresoxim-methyl and prochloraz-manganese chloride complex were highly toxic（Table 2）. Under pair-wise joint toxicity treatments, the effects of combinations of metolachlor/kresoxim-methyl and metolachlor/prochloraz-manganese chloride complex were moderately toxic, while the combination of kresoxim-methyl and prochloraz-manganese chloride complex was highly toxic（Table 2）. For the joint toxicity examined at 24 h, 48 h and 72 h, the LC50 values of metolachlor/kresoxim-methyl group were 18.41, 15.69 and 13.38 mg/L, respectively, with corresponding values of 15.56, 10.45 and 8.11 mg/L for metolachlor/prochloraz-manganese chloride complex group, and 4.17, 2.84 and 2.00 mg/L for kresoxim-methyl/prochloraz-manganese chloride complex group, respectively（Table 2）. The safe concentrations（SC） of metolachlor/kresoxim-methyl, metolachlor/prochloraz-manganese chloride complex and kresoxim-methyl/prochloraz-manganese chloride complex were 3.42, 1.41 and 0.40 mg/L, respectively（Table 2）. For toxic evaluations of pair-wise combinations of the three pesticides, the toxic effects of metolachlor/kresoxim-methyl group at 24 h and 48 h showed antagonistic, whiel kresoxim-methyl/prochloraz-manganese chloride complex group at 48 h showed adding effects, and the remain treatments showed synergistic（Table 3）. Likewise, the results of repeated measures ANOVA indicated that pesticide concentration, exposure time and their interactions significantly affected the tadpoles survival（Table 5）. Combined and compared the data previously published, we found that the tadpoles of B. gargarizans were highly sensitive to various pollutants. These results should provide us some valuable scientific references for further investigation of toxicity in anuran species.