Study On The Molluscicidal Effect And Toxicity Of META-Li Against Oncomelania In The Mountain Area

Objective: To observe the molluscicidal effect and toxicity to the non-target organisms of META-Li sprayed against oncomelania by comparing with niclosamide in the mountain area.Methods: The experiment was carried out in three run-down farmlands where the snails breeded and three ponds which connected with the farmlands in Yushan County. The fields were divided into a ridge group of META-Li,a field group of META-Li, a niclosamide group and a control group. The dosages of the ridge group of META-Li and the field group of META-Li were all 1 g/m2,and the dosage of the niclosamide group was 2 g/m2. The liquid volumes of the three groups were all 1 kg/m2. META-Li and niclosamide were sprayed in a sunny day, then their molluscicidal effects against oncomelania were observed parallelly. At the same time,some fishes,shrimps,Cipangopaludina chinensis Gray,frogs and ducks were stocked in each pond,and some goats were stocked in each farmland,then the influences of META-Li and niclosamide on the non-target organisms were observed parallelly.Results: 3days,7days,15days,2 months after spraying the drugs,the corrected snail death rate of the ridge group of META-Li was respectively 98.1%,97.4%,95.6%,97.9%;that of the field group of META-Li was respectively 80.8%,74.1%,88.8%,89.9%;that of the niclosamide group was respectively 95.6%,93.5%,95.9%,94.9%,and that of the control group was respectively 1.3%,1.1%,1.5%,1.4%. During the two months after sprayed the drugs,in the ridge group of META-Li and the field group of META-Li,the goats hadn't had any significant adverse reactions,and their habits of tending to the food hadn't changed;the stocking organisms in the ponds hadn't had any significant adverse reactions. In the niclosamide group, the goats hadn't had any significant adverse reactions,and their habits of tending to the food had weakened;the fishes,shrimps,frogs and Cipangopaludina chinensis Gray were all died in the first day after sprayed the drug;the ducks hadn't had any significant adverse reactions. All of the stocking organisms in the control group hadn't had any significant adverse reactions.Conclusion: In paddy fields and ditchs of the mountain area,the molluscicidal effect of META-Li against oncomelania is good in the near future,and it has no toxicity to the non-target organisms,but its long-term molluscicidal effect against oncomelania and its toxicity to the non-target organisms are to be observed further.