Field evaluation of a novel plant molluscicide“Luo-wei”against the snail Oncomelania hupensis III Molluscicidal effect by spraying method in hilly regions

Objective To evaluate the molluscicidal effect of a novel plant molluscicide"Luo-wei"(Tea-seed distilled saponins,TDS)against Oncomelania hupensis in hilly regions.MethodsThe molluscicidal effect of TDS at a dose of 5 g/m2by the spraying method against Oncomelania snails was assessed in a setting with a high snail density in Hushan Village,Jiangning District of Nanjing City,and the effect was compared with that of 50% wettable powder of niclosamide ethanolamine salt(WPN)at a dose of 2 g/m2 at different time after spraying.ResultsAfter1,3,7 and 15 day(days)of the spraying experiment,the snail death rates of the TDS group were 56.47%,57.32% ,90.58% and 93.41% respectively,while those of the WPN group were 49.22%,53.37%,95.92% and 97.26%,respectively. The differences between the rates of the 2 groups 1,7,15 day(days)after the spraying were statistically significant(all P0.05). Fifteen days after the spraying,the density of living snails reduced from 20.30±16.20 snails/0.1 m2and 23.67±21.22 snails/0.1 m2to 2.28±2.17 snails/0.1 m2and 1.27±0.76 snails/0.1 m2in the TDS group and WPN group,respectively,with the reduction rates of 88.77% and 94.63%,respectively.ConclusionTDS can be used as an alternative molluscicide for the control of Oncomelania snails in hilly areas,which deserves further popularization.