冬季水淹对洲滩钉螺生存繁殖影响的观察

在我国长江下游江边，采用现实验性水淹的方法，观察冬季水淹对钉螺生存影响及水淹后尚存活螺繁殖力变化。结果水淹３０、６０、９０、１２０天１５０天后其亡率依次为１．２５％、９．３０％、１９．２３％、３６．０５％和３６．７０％。经水淹６０－９０天，螺的产卵量减少１／２以上，所产卵的孵化率下降约１／３。观察提示，冬季持续一定时间水淹一定时间水淹对湖沼地区钉螺生存和繁殖均为不利。

OBSERVATIONS ON THE SURVIVAL AND MULTIPLICATION OF ONCOMELANIA SNAILS AFTER WINTER FLOODING IN MARSHLAND OF YANGTZE RIVER

Experimental wintre flooding of Oncomelania submerged in water during winter were snails collected from the marshland of the Yangtze River. Observation was made on the changes of their survival and multiplication.The results showed that the death rates of snails submerged in the Yangtze River for 30, 60, 90, 120 and 150 days were 1.25, 9.30, 19.23, 36,05 and 36.70% respectively. The death rates of the snails submerged for 60-150 days are significantly higher than controlling groups which were not submerged in water. The Oncomelania snails submetged for 60-90 days produced less number of eggs and the hatching rates were reduced.The conclusion was that winter flooding was a unfavorable factor both for survival and multiplication of Oncomelania snails in the marshland of the Yangtze River in china.