RESUMO
Objective To observe the molluscicidal effect of 25% suspension concentrate of niclosamide (SCN) against snail eggs and young snails. Methods The experiments with SCN and 50% wettable powder of niclosamide ethanolamide salt (WPN) against the snail eggs and young snails were carried out by the immersion method in laboratory. Results The death rates of snail eggs were both 100% in 0.25 mg/L active content of SCN and in 0.50 mg/L of WPN for 24 hours. The LC_~50(s) of SCN against Oncomelania snail eggs were 0.0506, 0.0496 mg/L and 0.0473 mg/L by immersion for 24, 48 hours and 72 hours respectively, while the LC_~50(s) of WPN were 0.1030, ~0.0962 mg/L and 0.0869 mg/L. The death rates of young snails were both 100% in 0.25 mg/L active content of SCN and WPN for 24 hours. The LC_~50(s) of SCN were 0.0625, 0.0474 mg/L and ~0.0442 mg/L for 24, 48 hours and 72 hours respectively, while the LC_~50(s) of WPN were 0.1088, 0.0825 ~mg/L and 0.0825 mg/L. Conclusion The SCN has high molluscicidal effect against Oncomelania snail in its different developmental stages: egg and young snail.[