钉螺对氯硝柳胺抗药性的实验研究

目的研究氯硝柳胺在现场长期使用后,钉螺对其产生抗药的可能性。方法捕捉安徽省铜陵县胥坝乡长期使用氯硝柳胺进行灭螺地区的钉螺作为实验螺,以该乡未使用过氯硝柳胺灭螺地区的钉螺作为对照螺。将氯硝柳胺用脱氯自来水配成有效浓度为2.0000、1.0000、0.5000、0.2500、0.1250、0.0625和0.0313mg/L的药液,在(24±1)℃下对实验和对照钉螺进行室内浸杀试验,观察钉螺死亡情况,计算半数致死浓度(LC50)等指标。结果浸杀24、72和120h后,实验组钉螺LC50分别为0.337、0.175和0.136mg/L,对照组钉螺的LC50分别为0.165、0.090和0.061mg/L;氯硝柳胺浓度为0.0625～0.0250mg/L时,实验组钉螺的死亡率均显著低于对照组。结论氯硝柳胺在现场长期使用后,钉螺可能对其产生抗药性。

Experimental study on the resistance of Oncomelania snails to niclosamide

Objective To study whether Oncomelania snails developed resistance to niclosamide after its long-term use in fields.Methods Snails in the experimental group were captured from the area where niclosamide was used long-term while snails in the control group were captured from an area where niclosamide was never used;the two areas were both located in Xuba Township,Tongling County,Anhui Province.Different concentrations of niclosamide,i.e.2.0000,1.0000,0.5000,0.2500,0.1250,0.0625,and 0.0313 mg/L,were prepared,and snails in the two groups were immersed in solutions of niclosamide at(24±1) ℃ in the laboratory.The snail mortality rate and the 50% lethal concentration(LC50) were observed.Results The LC50 for niclosamide used on the experimental group for 24,72,and 120 hours was 0.337,0.175,and 0.136 mg/L,respectively,while the LC50 for niclosamide used on the control group for 24,72,and 120 hours was 0.165,0.090,and 0.061 mg/L,respectively.Values for the former were markedly higher than those for the latter.The snail mortality rate in the experimental group was much lower than that in the control group when the concentration of niclosamide was from 0.0625 to 0.0250 mg/L.Conclusion Oncomelania snails may have developed resistance to niclosamide after its long-term use in fields.