ANALYSIS ON DISTRIBUTION SITUATION AND FLUCTUATION TREND OF HABITAT AREA WITH ONCOMELANIA HUPENSIS IN JIANGSU PROVINCE

Objective To understand the present situation of distribution and the fluctuation trend of the area with Oncomelania hupensis , and to clarify the reason of detected snail ridden area, and to provide scientific basis for formulating the control strategy. Methods The conventional methods was used to snail survey in every spring. The survey data was treated by SAS software. Results The areas with snail increased in 7.97% every year, in which, the areas of the infected snail increased in 18.33%. The correlation analysis showed that the areas of the infected snail are increasing with increasing of the snail habitats in marshland, plain with waterway networks and hilly regions. The snail ridden areas were mainly distributed to the marshland and lake regions in Nanjing, Zhengjiang and Yangzhou City in 2000. In the three Cities, the areas with snail made up 70.80%, 15.43% and 11.84% of the whole Province individually. However, the snail ridden areas made up 90.85% of the whole Province in the marshland and lake regions. The areas with snail were mainly located to some environments that have been not transformed. The characterisic of snail distribution in the marshland and lake regions indicated that environmental modification is effective to control snail. The snail areas in the river that is connected with the Yangtze River are the greatest in the plain regions with waterway networks. Without snail eradication was a cause with snail that made up 42.88% of the total snail infested areas. Other main cause was that the snail had not been eliminated thoroughly, that made up 42.53%. Thus snail control has been a serious problem in Jiangsu Province. Conclusion In recent years, the rise again on area and distribution of the snail habitats is serious in Jiangsu Province. The present measure of the snail control can not effectively stop the spreading and increasing of the snail.