| Objectives:Aiming at habitat of various Oncomelania hupensis sub-species and susceptibility of Schistosoma infection to Oncomelania hupensis robertsoni, we study the survival and reproduction of Oncomelania hupensis robertsoni in Lake-marshland and water network regions, in the aim of providing fundamental data for future ecological and Schistosomiasis biological competitive preventive research.Methods:1.Epidemical study of Schistosomiasis in HuangDan Village, Baimashi Town, Jiang Ling County, Hubei Province.2.Collect wild Oncomelania hupensis robertsoni samples in Sichuan Province and observe their survival with no food provided in artificial climate box. Calculate their life expectancy after leaving their original habitat by Animal Survival Table;3.Collect Oncomelania snails in wild experiment field and indentify Oncomelania hupensis robertsoni. Then we put those selected in wild experimental area after marking them properly, and examine the survival of Oncomelania snails every 3 months using Oncomelania hupensis hupenesis as control.Results:1.Number of target Oncomelania snails in experimental area shows gradual decline since the year 2004, while it rebounds after 2009. Positive Oncomelania snail density is less than 0.005/0.11m2. No positive target Oncomelania snail is detected in 2009 and 2010.The Kato-Katz positive rate of local people is decreasing in the past 4 year while Schistosoma infection rate remains, which may indicate Schistosomiasis epidemic is stabilizing. Schistosoma infection of cows is gradually declining.2. Survival rates of Oncomelania hupensis robertsoni and the control group are 54.5% and 61.0% respectively, one month after moving away from original habitat, without extra food provided. We calculate life expectancy of both to be 35.84 days and 41.16 days.3. Survival rates of Oncomelania hupensis robertsoni after 3 and 6 month can remain above 75% in above experiment condition. Over 20% of Oncomelania hupensis robertsoni survived even after 9 month. Differences between the 3 month survival rates of the two subspecies are statically significant (χ23个月=38.641,P<0.05). Survival rate of female Oncomelania snails and different species of male Oncomelania snails are significantly different (χ2at=13.255, P<0.05,χ2cg=4.882,P <0.05). Different numbers of the off springs from the two groups are detected after 9 month.4. Estimated number of Oncomelania hupensis robertsoni Danling strains is 1501.88±134.38 after 6 month survival (2009.10-2010.04).After breeding seasons (2010.07), most Oncomelania snails are from original group, with an estimated total number of Oncomelania snails to be 1587.17±429.09.However, the number drops to 210.34±151.69 in 2010.10. Estimated number of Pengshan strains after breeding seasons (2010.07) is 1112.63±292.48, and drops to 112.23±107.54 in 2010.10.Conclusions:1. Life expectancy of Oncomelania hupensis robertsoni Danling strains after moving out from original habitat is 35.84 days, indicating that there is enough survival time for them to undergo passive distant transfer.2. Oncomelania hupensis robertsoni Danling strains have over 20% 9months survival rate after moving to lake-marshland and water network regions, and are able to have off springs after breeding season. Female Oncomelania hupensis robertsoni and male Oncomelania hupensis hupenesis are able to cross mate and give ribbed shell offsprings.3.All three strains of Oncomelania hupensis robertsoni are able to survival and mate after moving to lake-marshland and water network regions. Species population decreases during short period of time. Part of the off springs are able to mature. |
PDF Full Text Request