南水北调东线工程防止钉螺扩散技术研究Ⅱ水源区保芦沙埋灭螺效果观察

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

目的评价南水北调东线工程水源区"保芦"沙埋灭螺效果。方法于钉螺产卵期将成螺置于不同含沙量的环境饲养7 d,观察产卵情况。将钉螺置于采用江沙制成的饲养盘,在实验室观察其生存情况。水源区现场试验观察沙埋灭螺前后钉螺密度变化和芦苇生长情况。结果钉螺在纯江沙环境不产卵,江沙含量10%～100%各组产卵数与江沙含量呈显著负相关(r=-0.965,P=0.008)。钉螺在江沙环境的死亡率随时间增加而上升,25℃左右3、6个月钉螺死亡率分别达96.00%和100%。现场灭螺沙埋后、次年春季、汛期后、第3年春季均未发现钉螺;对照组采用药物灭螺后2周,活螺密度下降93.65%,经过汛期,活螺密度较灭螺前上升100%,至第3年春季活螺密度仍为0.37只/0.1 m2。沙埋后次年春季芦草生长良好。结论江沙环境不利于钉螺产卵和生存;现场应用沙埋法具有"保芦"灭螺效果,似还具有防止汛期钉螺扩散作用;沙埋法符合环境保护要求,可应用于南水北调东线水源区和沿江滩涂湿地钉螺控制。

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 ℃ 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.