Effect of habitat fragmentation on the schistosome-transmitting snail Oncomelania hupensis in a mountainous area of China.

The effect of habitat fragmentation on schistosome-transmitting snails was assessed in an intervention village and a control village in Sichuan Province, China. Snail habitats were fragmented by environmental management. After 2 years, the proportions of quadrats with snails in the fragmented habitats decreased from 9.35% to 2.41% in one patch (c3) and from 12.20% to 6.57% in another patch (c12), whilst the proportions in habitats without fragmentation did not alter significantly. Mean snail density decreased from 0.246 to 0.063 snails/0.11 m2 in patch c3 and from 0.356 to 0.177 snails/0.11 m2 in patch c12, whilst the mean snail density of other patches did not alter significantly. Most snails from the same patch and/or its remaining patches after fragmentation clustered together in the phylogenetic tree, except for c1, c3 and its remaining patches (c5, c6 and c11). Snail habitats in the study zone exhibited visible fragmentation. Habitat fragmentation could decrease the snail population size and limit migration and dispersal of snails between patches.