不同方法对氯硝柳胺乙醇胺盐杀螺效果的评价

目的　比较不同方法对氯硝柳胺乙醇胺盐杀螺效果评价的差异 ,确定其现场使用的有效剂量。方法　采用开放式浸杀法和喷洒法测试氯硝柳胺乙醇胺盐杀螺效果 ,并以常规封闭式浸杀法和喷洒法进行比较。结果　氯硝柳胺乙醇胺盐药液 2 4 h开放式浸杀钉螺的 L C50 为 0 .6 6 18mg/L,常规封闭式浸杀钉螺的 L C50 为 0 .14 73mg/L,封闭式杀螺效果好于开放式 ,两者间差异有显著性 (t= 3.371,P<0 .0 5 )。开放式浸杀时钉螺逃逸数随药物浓度的增高而减少 ,当药物浓度达 4 .0 m g/L时 ,钉螺逃逸被完全抑制 ,大部分钉螺在 1h内逃逸。而开放式喷洒时 ,仅低剂量组有少量钉螺逃逸 ,开放式和封闭式喷洒杀螺效果差异无显著性。结论　常规药效测试方法可能高估了氯硝柳胺乙醇胺盐的杀螺作用 ,现行推荐剂量达不到实际需要的有效浓度。建议氯硝柳胺乙醇胺盐现场浸杀灭螺应用剂量 (指乙醇胺盐含量 ,下同 )为 2 - 4 mg/L,喷洒灭螺的现场应用剂量为 1- 2 g/m2。若考虑复杂环境或其它因素影响 ,则尚需酌情增加药物用量。

EVALUATION ON MOLLUSCICIDAL EFFECTIVENESS OF NICLOSAMIDE ETHANOLAMINE SAIT WITH DIFFERENT METHODS

ObjectivesTo compare the dif fer ence in the evaluation of molluscicidal effectiveness of niclosamide ethanolamin e salt with different bioassays, and to define the molluscicidal doses of niclos amide ethanolamine salt in the field. Methods The open immersion and sprinkle methods (without limit for water leaving behavi o ur of snail) were used to test effectiveness of killing Oncomela nia hupensis. Th e conventional close immersion and sprinkle methods were used as control.ResultsThe snails were immersed by niclosamide etha nolamine salt solution with the above two methods for 24 h respectively. The LC 50 (s) of the open and the close methods were 0 6618 mg/L and 0 1 473 mg/L respectively. The killing snail effect of the conventional close method was better than the open (t=3 371, P<0 05). When the sn ails were immersed in niclosamide ethanolamine salt solution with the open metho d, the water leaving snails decreased with the increasing of the concentration. When the concentration was 4 0 mg/L, the water leaving behaviour of snail was ful ly controlled. The great majority of the water leaving snails occurred within 1 h . When the open sprinkle were used to the molluscicidal test with niclosamide et hanolamine salt solution, there were few of snails to escape in the low concentr ations group. There was not significant difference between the open and close sp rinkle methods. ConclusionThe molluscicidal eff ectiveness of niclosamide ethanolamine salt might be highly estimated by the con ventional close bioassays method. The current recommended doses of killing snail may be lower than practical dose. It is suggested that the doses of the immersi on mollusciciding with niclosamide ethanolamine salt should be 2-4 mg/L, and the doses of the sprinkle be 1-2 g/m 2 in the field.