Molluscicidal effect comparison between TDS and MNSC in field

Objective To compare the molluscicidal effects between"Luo-wei"(TDS),a plant molluscicide in 4 percent,and metaldehyde and niclosamide(MNSC)in the field. Methods A natural ecological environment with Oncomelania hupensis was selected as the test area,the test concentrations of TDS and MNSC were 2.5 g/m3and 2 ml/m3respectively by the immersion method;the test doses of TDS and MNSC were 3 g/m2and 2 ml/m2respectively by the spray method;the doses of WPN in a control group were 2 g/m3and 2 g/m2respectively by the two methods above-mentioned. The molluscicidal effects between TDS and MNSC were compared by using the synchronous design method and parallel comparative method. Results In the TDS group,the death rate of snails was 90.70% by immersion for 24 hours,reached to 81.40% after spraying for 7 days,and there were no significant differences among the observation time points in molluscicidal effects(P0.05). One day after the spraying,the death rate of snails was less in the TDS group compared with that in the MSCN group(P0.01),but the death rates of snails were similar in both groups 3 days after the spraying(P0.05). In the MSCN group,the death rate of snails was 99.17% by immersion for 24hours,reached to 66.07% by spraying for 1 day. In the WPS group,the death rate of snails was 97.15% by immersion for 24hours,reached to 71.43% after spraying for 1 day,and there were no significant differences(both P0.05). Conclusion TDS has a good molluscicidal activity and stable efficacy,and the molluscicidal effect of TDS is similar to that of MSCN in the filed,butthemolluscicidalsensitivity of TDSis lower than that ofMSCN.