[Technology of preventing oncomelania snail diffusion in east route of South-to-North Water Diversion Project II. Effect of sand buried and reed protection on snail control in area of water source].

OBJECTIVE:To evaluate the effect of sand buried and reed protection on Oncomelania snail control in the area of water source of the east route of South-to-North Water Diversion Project. METHODS:The Oncomelania snail eggs were counted after the snails raised seven days in the sand of different contents in the spawning period. The survival of the snails was observed when the snails were raised on the sand surface in the laboratory. The change of the densities of living snails and reed growth were observed in the area of water source. RESULTS:The snails did not lay eggs in the pure sand environment. There was a negative correlation between the number of snail eggs and the content of sand (r = -0.965, P = 0.008). The mortality rates of the snails were increasing with the increase of the time in the sand environment. The mortality rates of the snails were 96.00% and 100% when the snails were raised 3 months and 6 months around 25 degrees C respectively. The field test showed that the snails were not discovered after the sand buried, the second spring, after the flood season, and the third spring. However, the density of living snails of the control group dropped by 93.65% 2 weeks after using molluscicide, but increased by 100% and kept in 0.37 snails/0.1 m2 after the flood season and the third year spring, respectively. The reed growth was good in the second spring after the sand buried. CONCLUSIONS:The sand environment is unfavorable for laying eggs and survival of the snails. The sand buried method has the effects of snail control and reed protection. In addition, the method could also prevent the snail spread in the flood season.