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目的 描述人工灌溉区钉螺生长繁殖特征,为实施生态学方法控制钉螺提供理论依据。 方法 在泾县陈村水库总干渠自流灌溉区选择一斗渠为观察点,于2002年8月~2003年 11 月,每月进行系统抽样查螺;每月随机抽样有螺框20框,室内逐只测量钉螺螺旋数和壳体长度,镜下观察雌螺并计数螺卵;全部钉螺解剖鉴定死活。同时测量水位并收集气象资料。 结果 2003年,2~4月份活螺密度最高; 7~9 月份钉螺死亡率最低;多数月份雌螺存活数量高于雄螺。雌螺含螺卵呈现明显的季节性变化,含卵雌螺数从6 月份开始减少,7 月时未见含卵雌螺,8 月份含卵雌螺数仅占观察雌螺数的9.79%,9月份占83.82%。幼螺(螺龄>3周)出现在6~10月,大多在6、7月份。但在2002年12月份幼螺出现1个小高峰。 结论 在陈村水库自流灌溉区,钉螺的新老交替可能发生在 7 月份,新生钉螺发育成熟可能在 9月份,而这一特征可能受年度间气温变化的影响。
Objective To describe the growth and reproduction characteristics of Oncomelania hupensis in artificial irrigated area and provide a theoretical basis for the ecological control of snails. Methods A series of ditches were selected as the observation points in the gravity irrigation district of Chencun reservoir in Jingxian County. From August 2002 to November 2003, systematic snail sampling was conducted every month; Only the number of spiral snails and shell length were measured. The female snails were observed under the microscope and the spiral eggs were counted. All snails were anatomized to determine their life and death. Measure water level and collect meteorological data at the same time. Results The live snail density was the highest from February to April in 2003, the lowest snail death rate in July to September. The survival rate of female snails in most months was higher than that of male snails. Female snail eggs showed obvious seasonal changes, oviposition of female snails began to decrease in June, no oviposition of female in July, oviposition of female in August accounted for only 9.79% of the female snail number, September accounted for 83.82%. Baby snail (screw age> 3 weeks) appeared in June to October, mostly in June and July. However, a small peak appeared in December 2002. Conclusion In the caculated irrigated area of Chencun reservoir, alternation of old and new snails may occur in July. The growth and development of Oncomelania may be in September, and this feature may be affected by the temperature change in the year.