地膜覆盖对不同土层的湖北钉螺影响观察

目的 观察农用地膜覆盖灭螺对土内钉螺和螺卵的影响.方法 选择潮湿的有螺田埂作为试验现场,分设施药覆膜组（采用50％氯硝柳胺乙醇胺盐可湿性粉剂,按2g/m2的剂量喷洒后覆盖地膜）、单纯覆膜组（不施药直接覆盖地膜）和对照组（不采取任何灭螺措施）.于施药覆膜后40 d和单纯覆膜后90 d分别对试验环境0、0～2、2～5、5～10和10～15 cm的土层进行钉螺调查.结果 覆膜40 d和90 d后,钉螺在土内分布的特点发生了改变,钉螺由土表向土内深层呈逐渐递增趋势（R2=0.9877,R2=0.7619）,土内钉螺死亡率高于对照组（x2=281.198,P＜0.001;x2=47.970,P＜0.001）,活螺平均密度较对照组均有下降（Z=-6.390,P＜0.001;Z=-4.681,P＜0.001）,幼螺的数量明显低于对照组（Z=-6.733,P＜0.001;Z=-5.131,P＜0.001）.结论 地膜覆盖对土内钉螺有很好的杀灭作用,并且可抑制钉螺第2代的繁殖和孳生.

Effects of film mulching on Oncomelania hupensis breeding in different soil layers

Objective To study the effects of film mulching on Oncomelania hupensis and its eggs in soil. Methods The damp ridges with O. hupensis snails were selected and divided into niclosamide/film mulching group （sprayed with 50% wettable powder of niclosamide ethanolamine salt at 2 g/m2 and covered with mulch）, film mulching group （covered with mulch without niclosamide spraying）, and control group （not treated by molluscicidal measures）. Snail investigation was conducted in different soil layers （0, 0-2, 2-5, 5-10, and 10-15 cm） at 40 d after niclosamide spraying plus film mulching and at 90 d after film mulching alone. Results At 40 d and 90 d after film mulching, the snail distribution in soil changed, increasing by degrees from soil surface to the deep layer of soil （R^2=0.9877; R^2=0.7619）; compared with those of control group, the mortality of snails in soil was significantly higher （X^2=281.198, P〈0.001; X2=47.970, P〈0.001）, the average density of living snails was significantly decreased （Z=-6.390, P〈0.001; Z=-4.681, P〈0.001）, and the number of young snails was lower （Z=-6.733, P〈0.001; Z=- -5.131, P〈0.001）. Conclusion Film mulching is effective in killing snails in soil and can control the reproduction and breeding of the second generation of snails.