Allelopathic potential of Nerium indicum on Oncomelania hupensis

The cardiac glycosides from fresh leaves of N. indicum effectively killed the Oncomelania hupensis. The mortality of O. hupensis treated with 20 mg/L cardiac glycosides for 3–4 d was similar to that treated with 1 mg/L niclosamidum for 2–3 d. The LD50 and LD90 values for the cardiac glycosides were 4.05 mg/L and 22.25 mg/L, respectively. The treated samples showed higher activities of EST isozyme in early stage and lower activities in middle and late stages and drastically decreased the glycogen content (from 9.9 to 32.6%) than control, however, the protein contents were not affected. We determined the molluscicidal activity of cardiac glucosides and the mechanisms for the allelopathical effects of cardiac glucosides on morphological pathology, metabolisms of sugar and protein of O. hupensis. We found the chemiecological evidence that N. indicum is capable of killing O. hupensis and plant molluscacide can control O. hupensis.