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目的了解输入钉螺的分布及扩散规律,为制定钉螺监测技术方案提供科学依据。方法选择约666 m2的荒地,用宽50 cm、深30 cm的水沟按棋盘分布分隔成约2 m2的方块,在一端的一块输入活钉螺1 600只,逐月抽样查螺观察有螺框率、活钉螺密度、幼螺密度、交配、分布距离、天气、温湿度等。结果2008年3～12月观察期间,有螺框率在20.00%～38.18%之间;晴天与阴雨天有螺框出现率分别为22.88%和29.24%,差异有统计学意义(χ2=4.113,P<0.05);荒地台地和小水沟边/底的有螺框率分别为9.38%和35.99%,差异有统计学意义(χ2=67.246,P<0.01),显示有螺框查出率与天气、环境等密切相关。9个月的观察期,有螺框钉螺、活钉螺、2代幼螺密度变化范围分别在2.17～5.71只/框、2.03～5.54只/框和0～4.56只/框之间,活钉螺、2代幼螺密度荒地台地明显低于小水沟边/底,分别为1.22只/框、0.78只/框和3.72只/框、2.82只/框;推算钉螺输入繁殖的2代钉螺生长至成熟可交配的钉螺的时间仅为5个月。观察期间,在第3条小水沟外未查获钉螺,单向扩散距离最远为4.5 m。结论钉螺主要分布在荒地有水区边缘如水氹、水沟边/底等潮湿、水分充足的地方,并沿水沟边扩散为主;输入钉螺阴雨天较活跃,查出率较高。
Objective To understand the distribution and diffusion rules of imported snails and provide a scientific basis for the development of snail monitoring technologies. Methods The wasteland of about 666 m2 was selected and divided into blocks of about 2 m2 by a ditch of 50 cm in width and 30 cm in depth. One 600 live snails were fed into one block at a time. Rate, live snail density, young snail density, mating, distribution distance, weather, temperature and humidity. Results During the observation period from March to December in 2008, the screw frame rates ranged from 20.00% to 38.18%. The occurrence rates of screw frames in sunny days and rainy days were 22.88% and 29.24%, respectively, with significant differences (χ2 = 4.113, P <0.05). The screw frame rates at the edge / base of the wasteland and the small ditches were 9.38% and 35.99% respectively, with significant difference (χ2 = 67.246, P <0.01) Weather, environment and other closely related. In the 9-month observation period, there were snail snails and live snails in the second generation. The density of snails in the second generation varied from 2.17 to 5.71 per box, from 2.03 to 5.54 per box and from 0 to 4.56 per box, The density of the second generation of young snail was significantly lower than that of the small ditches at the border of the shallow ditches, which were 1.22 / box, 0.78 / box and 3.72 / box, 2.82 / box respectively. Mating snails for only 5 months. During the observation period, snails were not found outside of Article 3 of the Xiaoshui Gully, and the unidirectional diffusion distance was 4.5 m. Conclusion The snails are mainly distributed in the wetlands have the edge of the water area such as water Taipa, ditches / bottom wet, adequate water and spread along the gutter side; input snail rainy days more active, higher detection rate.