Molluscicidal activities of Ginkgo biloba leaf against the snail Oncomelania hupensis

In search for new plant molluscicides that could be used to control schistosomiasis, the ethanolic and aqueous extracts of five medicinal plants:Ginkgo biloba, Torreya grandis, Ailanthus altissima, Peucedanum praerutorumand Herba agrimoniae from China were obtained to evaluate their molluscicidal activity against the snail Oncomelania hupensis. In all of the plant extracts, only the ethanolic extract of fallen leaf from G. biloba showed the highest toxicity on the snails within 48 h exposure. The petroleum ether fraction of ethanolic extract of fallen leaf from G. biloba (PFGB) showed significant activity against the snails and also revealed the time and dose dependent effect. Statistical analysis revealed that the LC50 values of PFGB was decreased from 72.38 mg·L-1 (24 h) to 9.22 mg·L-1 (72 h). Whereas, the LC50 values of PFGB to zebra fish was 131.34 mg·L-1. The glycogen and total protein content of soft tissues of snails decreased after treated with PFGB, and the decreasing rate was parallel to the molluscicidal activity. Therefore, the petroleum ether fraction of ethanolic extract of the fallen leaf from G. biloba exhibited promising molluscicidal activity against the snail and might be a potent molluscicides.   Key words: Ginkgo biloba, molluscicidal activity, Oncomelania hupensis, glycogen, total protein.