Relationship Between Sluicing for Irrigation and Spreading of Oncomelania hupensis in Hubei Province

Abstract

The snails Oncomelania hupensis, can drift into a ditch inside the sluice when it was opened for irrigation. Of 381 sluices on the dike of 14 main rivers in Hubei province, 226 (59.3%) of the sluices were snail – ridden inside and/or outside. Fifty of 226 sluices (22.1%) in the dich inside the sluice were confirmed being snail – ridden due to irrigation. The areas of snail spreading were 23,084.9 mu (1 mu = 0.00667 ha), or 68.57% of the snail habitats in areas covered by irrigation. The opening of sluices for irrigation would cause the snails to drift into the ditch inside the sluice. Such phenomenon did not correspond with the time when smail was found in the ditch inside the sluice. Also there was no singnificant difference during the investigation period from 1980 to 1987 and the size of snail habitats outside the sluice. There was no direct proportion to the number of outlets and the flow of sluice, the number of annual average days of opening sluices, and the frequency of opening sluices. Of 26 sluices with increasing number of snails, the increase in length and area of snail – ridden in the ditch inside the sluice was 2.26 times and 5.02 times respectively in 1987 to those in 1980. It showed that the speed of snail eradication could not keep pace with the speed of snail spreading.