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通过无锡等3个市、县1987～1990年的现场控制实验和河,沟钉螺调查,发现残存钉螺的消长与环境因子密切有关,只要自然环境适宜,即使1对钉螺,也能大量繁殖增长。在实验沟螺笼内放置1、5、10对钉螺,隔3年后,其钉螺密度分别增长171.9倍,69.5倍、28.4倍;螺口数分别增长354倍、135倍、75倍;现场1条水沟钉螺密度增长34.7倍,1条河钉螺密度没有增长,但都未见自然消亡。提示当达到“基本消灭”或“消灭”标准以后,应坚持长期监测。
Through the field control experiments in 1987 and 1990 in Wuxi and other counties and counties, the investigation on the snail and ditch snail found that the growth and disappearance of the surviving snail is closely related to the environmental factors. As long as the natural environment is suitable, even a pair of snails can multiply and multiply. 1,5,10 pairs of oncomelania were placed in the experimental trenches, and the nails density increased by 171.9 times, 69.5 times and 28.4 times respectively after 3 years; the number of snails increased by 354 times, 135 times and 75 times respectively; Ditch snail density increased 34.7 times, a river snail density did not increase, but no natural death. Hint When the standard of “basic elimination” or “elimination” has been reached, long-term monitoring should be adhered to.