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Objective To evaluate the molluscicidal effect of niclosamide ethanolamine salt powder?granula(PG)against Oncomelania hupensis. Methods The molluscicidal experiment was carried out by the dusting method with niclosamide etha?nolamine salt 4%PG. The experiments were respectively done in the laboratory and the tidal flats wetlands. At the same time , the niclosamide ethanolamine salt 4%dustable powder(DP)was as the control group. The single blind method was used for the quality control. The corrected mortality and the median lethal concentration(LC50)were compared between PG and DP in the molluscicidal experiment of the laboratory. The corrected mortality and the reduced rate of snails’density were compared be?tween PG and DP in the tidal flats wetlands. Results The mortality rates of the snails were 96.67%and 100%respectively on 1 d after dusting 4.0 g/m2 of 4% PG and 2.0 g/m2 of 4% DP in the laboratory. The results showed that the mortality rates of the snails were higher with 4%DP than 4%PG in each dosage(t1 d=3.60,P0.05). Conclusions 4%PG has both the adsorption of powder and the penetrability of the granules. The molluscicidal effects of 4%PG and 4%DP are almost the same. However,the drift of the powder was still not effectively controlled. This problem need to be further studied.
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Objective To study the drifting law of floats and potential risks of Oncomelania hupensis diffusion in the water diversion rivers of the east route of South?to?North Water Diversion Project. Methods The O. hupensis snails in the river chan?nels were monitored by the salvage method and snail luring method with rice straw curtains,and the diffusion possibility of snails along with water was assessed through the drift test of floats with GPS. Results In the flood seasons from 2006 to 2013, totally 8 338.0 kg of floats were salvaged,and 2 100 rice straw curtains were put into water in the Li Canal and Jinbao shipping channel,but no Oncomelania snails were found. The drift test of floats with GPS before water diversion showed that the flow ve?locity on water surface(northbound)was 0.45 m/s,the average drift velocity of the floats was 0.56-0.60 m/s,and the average drift distances each time were 999.70- 1 995.50 m in the Gaoshui River section,while there were no obvious drift in Jinbao shipping channel section. During the water diversion period,the flow velocity on water surface(northbound)was 0.45 m/s,the average drift velocity of the floats was 0.35-0.41m/s,and the average drift distances each time were 1 248.06-1 289.44 m in the Gaoshui River,while in Jinbao shipping channel section,the flow velocity on water surface was 0.28 m/s,the average drift velocity of the floats was 0.25- 0.27 m/s,and the average drift distances each time were 477.76- 496.38 m. The drift test showed that the floats gradually closed to the river bank as affected by water flow,wind direction and ship waves,when blocked by the reeds,water plants or other obstacles,and they would stopped and could not continue to drift without outside help. Con?clusions There are no Oncomelania snails found in the river channels of the east route of South?to?North Water Diversion Proj?ect. The drifting distance of the floating debris along with the water is restricted by the flow rate and shore environment.
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Objective To understand the distribution of the river beach wetlands and Oncomelania snails in the lower reach-es of the Yangtze River,and explore the countermeasures of snail control. Methods The river beach wetlands outside the Yang-tze River levee were investigated and classified according to the hierarchical and classification system of wetlands of China. The snail survey was carried out in the beach wetlands of Runzhou section of lower reaches of the Yangtze River from 2004 to 2013. The change trend of snail areas and the densities was analyzed in the wetlands. Results The river beach of Runzhou section of lower reaches of the Yangtze River belongs to the riverine wetland. There was Oncomelania snail breeding except the permanent wa-ter area. At present,there were natural wetlands of 1 303.0 hm2,human-made wetlands of 1 479.0 hm2 and wetland function chang-es of 1 059.0 hm2 in the river beach of Runzhou section. There was the snail area of 181.4 hm2 in the natural wetland in 2013. The area of snail control by the molluscicide and environmental modification was 4 624.55 hm2 from 2004 to 2013. The decline rates of snail areas and densities were 66.53%and 77.66%respectively. The existing Oncomelania snails were distributed in the natural wetlands. Conclusion The human-made wetland is helpful to snail control. The snail control in the river beach wetlands should attach a great importance to the protection of wetland ecology.
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Objective To understand the distribution of Oncomelania hupensis snails in source areas of the east route of Southto-North Warter Diversion Project and evaluate the effects of the snails on the safety of water transfer.Methods The investigation of snail distribution was carried out in the source areas of the east route of South-to-North Warter Diversion Project every spring.The method of the random sample combined with environmental sample was used for the field investigation.The beach land in the stilling pool of Jiangdu Pumping Station was selected as a surveillance site to observe the snail spread.Results The areas of the snail habitats and infected snails were 256.11,184.55,164.92,121.16 hm~2 and 8.27,1.0,1.0,0 hm~2 respectively in the source areas of the east route of South-to-North Wafter Diversion Project from 2006 to 2009.The densities of living snails had a downtrend,too.Google Earth showed that the areas of snail habitats distributed mainly in the Jiajiang River and Mangdao River in the source areas.The snail habitats were detected in the beach land in the stilling pool of Jiangdu Pumping Station.The research results showed that the snail spread related to the wastes from the river of drawing water.Conclusion There are the risks of snail spread in the source areas of the east route of South-to-North Wafter Diversion Project,so that the long-term surveillance and control on the snails is very necessary.
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0. 05), but both less than that of the lower or stirring excrement (P
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Objective To explore the rela ti onship between the environmental temperature and the oxygen demand of [WT5” BX]Oncomelania snails, and the relationship between the hiber nation or aestivation and the oxygen demand of snails.Me thods The oxygen demand of Oncomelaniasnails between 0 ℃ and 40 ℃ was determined by increasing the temperature gradually in lab, the relationship between the environmental tempera ture and the oxygen demand, and the correlative relationship between the oxygen demand and the percentage of snails in hibernation or aestivation were analysed. Results The oxygen demand increased as the tem perature rose between 1 ℃ and 36 ℃, and the regression equation between the oxygen demand and the variation of environmental temperature was [WT5”BX ]=6.6?10 -5-3?10 -6x+4.4?10 -6x2-8?10 -8x 3(R2=0.998,F=2775,P
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Objective To understand the e ff ectiveness of parasite ova sediment and non-hazardous treatment of two-grille la trines. Methods Two-grille latrines were recon n oitered in the field according to the non-hazardous treatment criteria, and th e sediment of parasite ova, the value of fecal coliform bacteria, NH 3-N, CODcr of the samples from the Grille 1 and Grille 2 of latrines were detected.Results The structure of some two-grille latrines was n o t in accord with the non-hazardous treatment criteria.Parasite ova were detecte d from the Grille 2 of one latrine. Six of 16 latrines were not eligible for non -ha zardous treatment according to the value of fecal coliform bacteria in Grille 2. Conclusion It is not suggested to popularize th e two-grille latrine yet, but it can be used as an interim form for excrement n on-hazardous treatment in rural areas. [
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0.05). There were significant differences among 3- or 6- or 9- or 12-hour groups and 24- or 36-hour groups in 6, 13 ℃ and 28 ℃ respectively (P
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Objective To evaluate the mid-term effectiveness of the medium-and-long-term programme of the prevention and control of schistosomiasis in Jiangsu Province. Methods The programme was carried out in Jiangsu Province and the comprehensive measures relied mainly on snail control, detection and chemotherapy of schistosomiasis for residents and livestock. The mid-term effectiveness of the programme was observed and evaluated longitudinally. Results The coverage rate of snail control areas and the ratio of chemotherapy of schistosomiasis for residents and livestock rose year after year. The snail areas, the infected snail areas and the infection rate of schistosome for residents and livestock reduced year after year. There were negative correlations between the coverage rates of snail control and the infected snail areas, the number of settings with infected snails, the infection rate of schistosome for residents, the infection rate of schistosome for livestock and the morbidity of acute schistosomiasis, respectively (rInfected snail areas=-0.897,P=0.039;rNo. of settings with infected snail=-0.937,P=0.019;rInfection rate for residents=-0.913,P=0.031;rInfection rate for livestock=-0.991,P=0.001;rMorbidity of acute schistosomiasis=-0.894,P=0.041). There were negative correlations between the ratio of chemotherapy of schistosomiasis for residents and the infected snail areas, and between the ratio of chemotherapy of schistosomiasis for livestock and the infected snail areas (rRatio of chemotherapy for residents =-0.965,P=0.008;rRatio of chemotherapy for livestock=-0.921,P=0.027). There were negative correlations between the funds of schistosomiasis control and the infection rate of schistosome for residents livestock, respectively (rInfection rate for residents=-0.897,P=0.039;rInfection rate for livestock=-0.971,P=0.006). The multiple linear regression analysis showed that there were the linearity relationships between the infection rate of schistosome for residents and the coverage rates of snail control, and between the infection rate of schistosome for livestock and the coverage rates of snail control, and between the morbidity of acute schistosomiasis and the coverage rates of snail control. Conclusions The effect of the comprehensive strategy of schistosomiasis control which relies mainly on snail control, detection and chemotherapy of schistosomiasis for residents and livestock are remarkable. The snail control and chemotherapy are effective and immediate. The increased funds would be essential guarantee for control and elimination of schistosomiasis.
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Objective To develop two-grille latrines with the effect of non-hazardous treatment. Methods According to the result of the pretest, one type of two-grille latrines was selected and constructed and its effect of non-hazardous treatment was evaluated. Results The faces-treatment pool, with cement-prefab structure and obturation, had a total cubage of 1.32 m3. The average total amount of faces in the pool was 1.05 m3 per family per month, and the pool could store the faces for over 34 days. The “reaching criteria rate” of the parasite ova sediment and the value of the fecal coliform bacteria were 100% among the excrement in the outlet. Conclusions The prefab two-grille latrines can reach the criteria of non-hazardous treatment, and they can be used in well-off rural areas without the usage of manure.
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Objective To observe hibernation phenomena of Oncomelanai hupensis and explore the way of inducing the hibernation in laboratory. \ Methods\ Snails, O^hupensis hupensis, were collected from marshland of Jiangsu. The snail hibernation was induced by the way of cultivation at a mimic natural environment in the laboratory with gradually changing temperature. The amount of oxygen consumed by snails was tested by iodine titration, and their hibernation was tested by pin puncture followed by warm water. \ Results \ There was no significant difference on the rate of snail \{hibernation\} when the temperature was reduced by 1 ℃ per 24 hrs and by 1 ℃ per 48 hrs. The hibernation rate \{increased\} with the decreasing temperature. There was a significant regression relationship between hibernation rate and temperature with R\+2=0^967 (F=207^72, P