RESUMO
Objective To explore the relationship between the Yangtze River floodplain ecological environment(vegetation, soil,water and light intensity)and the distribution of Oncomelania hupensis snails,so as to provide the evidence for ecological snail control. Methods Three regions(the Lu-Gang Bridge,Dragon Nest Lake in the bund,and Dragon Nest lake beach)were selected to investigate the plant characteristics(species,height,coverage,frequency and strain of clusters),soil characteristics (temperature,humidity,light intensity)and pH value. All the results were analyzed statistically with SPSS 18 software. Results A total of 920 boxes were investigated. The vegetation coverage was 3.7%-63.5%,and the dominant population was Cyperusrotun-dus L. cluster on the marshland. The soil temperature was 19.0℃-24.0℃,pH 5.0-5.7,and humidity 53%-75%. There were statis-tical significants in average number of living snails and dead snails among 3 groups( P<0.05). As the light intensity was strong in summer and weak in winter,the snails were in the back surface in summer and front surface in winter respectively. The average number of living snails was the most near the water. The difference was statistical significant(P<0.01)among three ranges(0-1 m,1-3 m and 3-5 m). Conclusion The snail survival and distribution have close relations with micro ecological environment factors,such as vegetation,soil,water and light intensity.
RESUMO
Objective To explore the relationships between micro-ecological environmental factors and the density of Snails so as to provide information for the elimination of Snails and control of Schistosomiasis disease,under ecological methods.Methods A bottomland close to Junshan Park in Yueyang city,Hunan province was selected as the field for survey during 10,2007-10,2008,and a systematic sampling method was applied to determine the specific sites of Snail investigation.All the Snails in each frames were collected and the soil surface temperature and vegetation coverage in several frames were measured.30 g soil sample in each selected frames were also collected simultaneously.The number of live Snails in each frame was counted by dissection,and soil measured pH value and soil moisture were tested in the laboratory.The distribution of Snails and microecological environmental factors,fitted general additive model for the relationship of these factors and the Snail density were described.Results 104 frames were surveyed,with pH value as between 4.70-7.92,vegetation coverage as in 1% to 96%,soil surface temperature as in 14.5-32.7℃,the soil moisture as in 0.07-2.00.Under General additive model,data showed that there was no significant difference for vegetation coverage.However,other factors were all significantly different(P＜0.001).It was found that a nonlinear relationship was existing between these factors and the Snail density.Conclusion Smoothing function relationship was noticed between the Snail density and micro-ecological environmental factors.It's suggested to fit general additive model to study the relationship between the distribution of Snails and its influencing factors,so as to adopt appropriate measures to change the related ecology to control the diffusion and reproduction of Snails.