[Snail control effect of film covering method in fish ponds and ditches].

To evaluate the snail control effect of a film covering method in fish ponds and ditches. Two fish ponds and 2 ditches with Oncomelania snails were selected as pilots, and 1 fish pond as Group A1 and I ditch as Group B1 received niclosamide spraying + film covering, and another fish pond as Group A2 and another ditch as Group B2 received niclosamide spraying only. The snail control effects were observed at 15, 30, 90 d and 360 d after the test, and the fish and other aquatic were also observed. In Group A1, the adjusted mortality rates of snails were 92.31%, 99.36% and 100% at 15, 30 d and 90 d after the test, respectively; in Group B1, the adjusted mortality rates of snails were 91.45%, 95.84% and 100% at 15, 30 d and 90 d after the test, respectively; and there was no death of fish. The densities of snails were 0 and 0.07 snails/0.1 m2 one year after the test, respectively. In Group A2, the adjusted mortality rates of snails were 75.36%, 72.59% and 65.76% at 15 d, 30 d and 90 d after the test, respectively; in Group B2, the adjusted mortality rates of snails were 70.36%, 72.87% and 75.82% at 15, 30 d and 90 d after the test, respectively; and there was death of fish. The densities of snails were 0.11 snails/0.1 m2 and 0.13 snails/0.1 m2 one year after the test, respectively. In ponds and ditches with snails, the niclosamide spraying + film covering method is very effective and safe.