Response of Oncomelania snail distribution on land use in Sichuan, China
Schistosomiasis is one of the four major infectious diseases that require prevention and control in China. It is mainly distributed along the middle and downstream areas of the Yangtze River and some hilly areas in Sichuan, Yunnan, and so on. Oncomelania snail is the only intermediate parasite in the schistosome life cycle; thus, reducing the number of snails can decrease the incidence of schistosomiasis by limiting its transmission. The number and distribution of snails is closely related to the environment, which is largely influenced by different habitats. To determine the relationship of snail number and spatial distribution with typical habitats, we selected different land use/plant cover types, investigated the snail distribution and analyzed the physical and chemical properties of the soil. The results show that among the different land use types, higher rates of live snail and live snail frame occurred along the riverbanks, wild land and ditches, followed by dry land, paddies, and forest lands. No live snail was found in bamboo stands of Sinocalmus affinis. An analysis of the physical and chemical properties of different land use types revealed higher soil pH value (8.41) in bamboo stands, which is beyond the suitable range for snails and possibly the key to inhibiting snails’ survival. These results imply that in the land growing bamboo (Neosinocalmus affinis) the snail could not propagate owing to soil pH rising. Therefore, the research would provide to some extent, the guidance for snail control through optimizing land use systems.
Key words: Bamboo stand, habitat, Oncomelania snail, Neosinocalmus affinis.