Molluscicidal activity of Saraca asoca and Thuja orientalis against the fresh water snail Lymnaea acuminata

The molluscicidal activity of bark powder of Saraca asoca, leaf powder of Thuja orientalis against the snail Lymnaea acuminata was studied. The molluscicidal activity of all the plant products was found to be both time and concentration dependent. The 96 h LC50 of T. orientalis leaf powder against L. acuminata was 250.5 mg/l. Ethanol extracts were more toxic than other organic extracts. The ethanol extract of T. orientalis leaf (24 h LC50: 32.74 mg/l) was more effective than that of S. asoca bark (24 h LC50: 82.38 mg/l). The 24 h LC50 of column purified fraction of T. orientalis leaf and S. asoca bark powder was 29.25 and 64.89 mg/l, respectively. Saponin and thujone were identified as active molluscicide components in the bark of S. asoca and leaf of T. orientalis, respectively. The product of S. asoca and T. orientalis may be used as potent molluscicides.