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In order to study the bacterial community composition and corresponding function in Wuliangsu Lake at the end of the Hetao Plain during the irrigation gap period, lake samples were collected in September 2020, and the pH, TN, TP, DIP, DTP, NH 4 + -N, Chla, EC, SAL, and other indicators were analyzed. The 16S rRNA high-throughput sequencing method was used to explore the attached bacteria and bacterioplankton in 15 samples of the surface water in Wuliangsu Lake. The experimental results showed that:① the alpha diversity Chao and Shannon indices of attached bacteria were greater than that of bacterioplankton, but the median of Shannoneven index was the same. ② In each sampling point, the bacterioplankton of Proteobacteria and Actinobacteria in the top five dominant bacteria phyla were higher than that of attached bacteria, and the abundance of attached bacteria and bacterioplankton of Bacteroidota were staggered. On the contrary, the contents of attached bacteria of Verrucomicrobiota and Cyanobacteria were all higher than that of bacterioplankton. ③ Redundant analysis showed that pH had the most significant effect on dominant attached bacteria, and the effect of conductivity and salinity in dominant bacterioplankton was the most significant. ④ PICRUSt2 function prediction analysis showed that attached bacteria and planktonic bacteria had the strongest metabolic functions, showing abundant metabolic functions. There were 29 nitrogen-related effective KOs and 88 phosphorus-related effective KOs, with the greatest nitrogen-fixing function and strong inorganic phosphorus-dissolving function, and bacterioplankton played a greater role in the two functions.

Bacteria are the key components of water ecosystems, and play important roles in material and energy cycle processes. To understand the changes in the bacterioplankton community in frozen lakes, we collected 15 "bottom ice" samples and 15 "surface water" samples under the ice sheet from Dali Lake, which is an inland closed lake in the Inner Mongolia Plateau. Combined with comparisons of the physicochemical proxies between "bottom ice" and "surface water" samples, the phylum community characteristics of the bacterioplankton were analyzed in detail. Although the bacterioplankton were mainly comprised of Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, and 11 other phyla in the "bottom ice" and "surface water", the average relative abundances of the dominant planktonic bacteria were clearly different. For example, the average relative abundance of Proteobacteria was approximately 63.64% in the "bottom ice" samples, but decreased to approximately 26.75% in the surface water samples, which was visibly smaller than the relative abundance of Actinobacteria with an average value of approximately 39.10%. We concluded that the changes in the contents of nutrient elements and physicochemical proxies must be the primary factors influencing the changes in the bacterioplankton community in the frozen Dali Lake. The changes in the physicochemical proxies could have been responsible for the changes in the bacteria community in the "bottom ice" and "surface water". Otherwise, the different physiological characteristics of the planktonic bacteria phyla caused the different responses to the changes in the contents of the nutrient elements and physicochemical proxies in the frozen lake. For example, the major bacterioplankton phyla were mainly influenced by the changes in total phosphorus and dissolved total phosphorus in the "bottom ice" and by the changes in dissolved inorganic phosphorus and ammonia nitrogen in the "surface water". The results will provide basic data to analyze the lake ecological environment in Northern China.

Objective: To understand the situation of the freely grazing and wild feces behaviors of residents in plateau mountain area of schistosomiasis endemic areas in Yunnan Province., Methods: Two villages of Xidian and Moguang in Heqing County, Yunnan Province were selected as the study area and the questionnaire surveys were performed to the randomly selected villagers aged 6 to 65 years with the sampling ratio of 30%. Then the respondents were tested for the infection of schistosomiasis by indirect hemagglutination assay (IHA)., Results: Totally 412 residents were surveyed. In all the responds, the ratios of "captive breed", "freely grazing "unknown" and "no response" were 55.34%, 4.85%, 26.94% and 12.86% respectively; and the ratios of "no grazing", "less than 5/week" and "no less than 5/week" were 75.49%, 16.02% and 8.50% respectively; and the ratios of "no wild feces", "less than 5/week", "no less than 5/week" and "no answer" were 68.45%, 27.67%, 2.91% and 0.97% respectively., Conclusions: Freely grazing and wild feces behaviors of residents in schistosomiasis endemic area of Heqing County are widespread, could heavily affect the control of schistosomiasis in Heqing County. The further work is to strengthen the management of human and animal feces and grazing and consolidate the results of the prevention and control of schistosomiasis and finally achieve the aim of the transmission interruption.

Objective: To understand the status of water contact and labor practice of residents in plateau mountain schisto- somiasis endemic areas in Yunnan Province, so as to provide the evidence for formulating the strategy of prevention and control of schistosomiasis in the next step of work., Methods: A total of 412 residents aged 6-65 years old in 2 villages were randomly sampled and investigated with questionnaires for their water contacts and labor practices in plateau valley schistosomiasis endem- ic areas. Then the schistosome infection status of the residents was surveyed with the indirect hemagglutination assay (IHA). RE- SULTS: Among the 412 residents investigated, the rate of water contact was 88.35%, and the main causes of water contact were watering, and swimming and playing. The percentages of residents who had schistosomiasis history were 1.16%, 0.00%, 30.80%, 3.85%, and 0 in them who had swimming and playing water-contacts, bathing, watering, washing hands, and others, respectively (χ2 = 38.96, P < 0.01). The positives of IHA in the above-mentioned residents were 18.60%, 0.00%, 37.60%, 23.08%, and 0, respectively (χ2 = 12.61, P < 0.05)., Conclusions: The productive infested water contact is the main way of schistosome infection. Therefore, the changes of labor practices and water contact of the residents are very important for the ef- fective prevention and control of schistosomiasis transmission.

Objective: To evaluate the molluscicidal effect of 5% powder of niclosamide ethanolamine salt granules (NEG) in the field of mountainous areas in Yunnan Province., Methods: The grasslands with Oncomelania hupensis snail habitats were chosen in Beideng Village, Heqing County, Yunnan Province, and were divided into 7 groups (groups of NEG 30 g/m2, NEG 40 g/m2, NEG 50 g/m2, NEG 40 g/m2 plus obstacle clearing, 50% niclosamide ethanolamine salt wettable powder (WPN) 6 g/m2, WPN 6 g/m2 plus obstacle clearing, and fresh water). The snail death rates and the densities of living snails were investigated and the results were compared in the different groups 7 d, 15 d, and 30 d after the implementation., Results: Seven d, 15 d, and 30 d after the implementation, the snail death rates of the groups of NEG 30 g/m2, 40 g/m2, and 50 g/m2 were from 72.75 % to 95.83%, and the average descent rates of living snail densities were from 72.26% to 95.54%. Seven d, 15 d, and 30 d after the implementation, in the NEG 40 g/m2 group, the snail death rates were from 81.69% to 87.19%, and the average descent rates of living snail densities were from 81.42% to 87.91% ; in the NEG 40 g/m2 plus obstacle clearing group, the snail death rates were from 84.89% to 88.24% and the average descent rates of living snail densities were from 85.63% ~ 88.22%; in the WPN 6 g/m2 group, the snail death rates were from 85.23% to 86.17% and the average descent rates of living snail densities were from 85.76% to 86.05%; in the WPN 6 g/m2 plus obstacle clearing group, the snail death rates were from 88.89% to 92.10% and the average descent rates of living snail densities were from 86.71% to 92.20%. The obstacle clearing improved the molluscicidal effect., Conclusion: NEG has a good molluscicidal effect in the field of mountainous areas in Yunnan Province.

Objective: To evaluate the effect of comprehensive schistosomiasis control measures based on infection source control in plateau mountain areas of Yunnan Province., Methods: From 2006 to 2004, four administrative villages were selected as test areas from plateau canyon and plateau basin endemic areas in Jindun Town, Heqing County, two villages each type, and the comprehensive control measures were implemented, including the examination and treatment of schistosomiasis, Oncomelania hupensis snail survey and control, health education, improving drinking water and lavatories, banning grazing, constructing sanitary pen of livestock, replacing cattle with machine, etc. The schistosome infection state and snail status in 2006 were treated as the baseline information, and the effect of the comprehensive measures were evaluated. Results The infection rate of human in plateau canyon areas decreased from 4.94% in 2006 to 0.06% in 2014, and that of livestock decreased from 1.11% to 0. In plateau basin areas, there was only 1 case of schistosomiasis found in Xiaolian Village in 2007, and no any other cases found in the other years, the infection rates of livestock dropped from 7.38% to 0. Compared with 2006, the snail areas in the two type areas decreased by 74.89% and 75.30%, respectively, meanwhile, the percentage of snail area, the occurrence rate of frames with snails, as well as the average density of living snails also decreased, and no infected snails were found since 2008. Xidian and Xinzhuang villages in plateau canyon area reached the criteria of schistosomiasis transmission controlled in 2009, and Xiao-lian and Kangfu villages in plateau basin reached the criteria of transmission interrupted in 2014., Conclusions: The comprehensive schistosomiasis control measures based on infection source control can effectively control the endemic situation of schistosomiasis in plateau areas of Yunnan Province. In the future, we should pay an equal attention to the infection sources control and snail control to consolidate and amplify the achievement of schistosomiasis control.

Objective: To evaluate the effect of a novel plant molluscicide, 4%"Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania hupensis snails in plateau mountain areas in Yunnan Province., Methods: The immersing and spraying experiments were carried out in the ditches and grassland of Xiaolian Administrative Village in Heqing County, Yunnan Province, to assess the molluscicidal effect of 4% TDS comparing with 50% wettable powder of niclosamide ethanolamine salt (WPN) in different environments and time., Results: After immersion for 24, 48 h and 72 h, the snail death rates were 70.67%, 87.33% and 98.67% in the TDS group, whereas being 77.33%, 96.67% and 100.00% in the WPN group, respectively. The differences of the death rates between the two groups 24 h and 72 h after immersing were not statistically significant ( chi2(24h) =1.73, chi2(72h) = 2.01, both P values > 0.05). Seven days after the immersing experiments, the occurrence rate of frames with living snails and the death rate of snails were 20.00% and 93.03% in the TDS group, while those were 13.33% and 95.76% in the WPN group, and there were no significant differences of the 2 indexes between the 2 groups ( chi(2)(Occurrence rate) = 2.27, chi(2)(Death rate) = 0.94, all P values > 0.05). After spraying for 1, 3, 7 d and 15 d, in both groups, the occurrence rates of frames with living snails and the average densities of living snails gradually declined, while the death rates of snails gradually increased with the extension of time. There were no statistically significant differences of the above 3 indexes between the 2 groups (all P values > 0.05). Fifteen days after the spraying experiment, the occurrence rate of frames with living snails and the adjusted death rate of snails were 15.00% and 87.39% in the TDS group and those were 16.67% and 89.32% in the WPN group, respectively., Conclusion: The molluscicidal effect of TDS is satisfying in plateau mountain areas, and the molluscicide is worthy of further extension and application.

The molluscicidal effects of 10% salt of quinoid- 2' ,5-dichloro-4'-nitrosalicylanilide (LDS) with dusting method, 26% amine molluscicide (MNSC) and 50% niclosamide (WPN) with insufflation method were tested in the fields of mountainous areas of Yunnan Province. After 7, 15 and 30 days of the tests, the death rates of snails, decline rates of living snail densities, and occurrence rates of frames with living snails of the 10% LDS group were 72.69%-87.16%, 74.10%-88.84%, and 20.00%-30.00%, respectively; those of the 26% MNSC group were 66.21%-91.06%, 69.55%-91.36%, and 19.44%-27.78% respectively; those of the 50% WPN group were 78.10%-90.18%, 82.44%-91.60%, 17.50%-20.00%, respectively. The results showed that the molluscicidal effects of 10% LDS, 26% MNSC and 50% WPN were basically equal.

Objective: To evaluate the effect of comprehensive control and management of schistosomiasis at plateaus regions in Yunnan Province., Methods: Xiaolian and Kangfu villages at plateaus regions where schistosomiasis was endemic were selected as study areas from 2006 to 2011, the schistosomiasis comprehensive control measures were conducted, and these measures included the health education, chemotherapy, stool and water management, grazing forbidden, Oncomelania snail control, etc. combined with the infrastructure of farmland water conservancy, agricultural comprehensive development, adjustment of industry structure, returning farmland to forest, ditch hardening, and aquaculture., Results: At Xiaolian Village, no schistosomiasis patient and livestock were found from 2008; and at Kangfu Village, no schistosomiasis patient was detected from 2006 and no schistosomiasis domestic animal was found from 2008. In 2011, the snail area, percent of frames with living snails, the number of snails, average concentration of living snails, and the highest concentration of living snails descended by 69.99%, 81.86%, 88.86%, 89.71%, 57.95% at Xiaolian Village, and descended by 27.65%, 1.11%, 94.71%, 92.16%, 88.00% at Kangfu Village, respectively, compared with those in 2006. The ratios of infected snail area to snail area were 68.91% in 2006 and 69.13% in 2007 at Xiaolian Village, and 61.73% in 2006 and 43.24% in 2007 at Kangfu Village. There were no infected snails from 2008 in the two villages., Conclusion: The comprehensive control and management measures can effectively control the schistosomiasis prevalence at plateaus regions.

Objective: To evaluate the molluscicidal effect of 26% suspension concentrate of metaldehyde and niclosamide (MNSC) in the fields of mountainous areas in Yunnan Province., Methods: Some representative Oncomelania snail environments of schistosomiasis endemic regions were selected as study areas in Heqing County, Yunnan Province and 26% MNSC and 50% wettable powder of niclosamide ethanolamine salt (WPN) were used to kill the snails with the mechanical spraying and sprinkler spraying methods respectively., Results: Seven, 15, 30 days after the spraying with the mechanical spraying method, in corn fields, the snail mortality rates were from 88.68% to 92.88% in the MNSC group, and from 89.86% to 90.32% in the WPN group respectively, and in the ditch, the snail mortality rates were from 89.97% to 94.46% in the MNSC group and from 90.08% to 96.74% in the WPN group respectively, and there was no significant difference between the 2 groups (P > 0.05); 7, 15, 30 days after the spraying with the sprinkler spraying method, in corn fields, the snail mortality rates were from 66.14% to 89.11% in the MNSC group, and from 78.40% to 91.22% in the WPN group, respectively, in the ditch, the snail mortality rates were from 84.13% to 94.27% in the MNSC group, and from 85.81% to 95.26% in the WPN group respectively, and there was no significant difference between the 2 groups (P > 0.05)., Conclusion: 26% MNSC has good molluscicidal effect in the fields of mountainous areas in Yunnan Province

Objective: To observe the molluscicidal effect of a novel molluscicide, salt of quinoid-2', 5-dichloro-4'-nitrosalicylanilide (LDS) on Oncomelania hupensis in laboratory and field of mountainous areas of Yunnan Province., Methods: With the immersion method, 10% LDS with concentrations of 0.1, 0.2, 0.4, 0.6, 0.8 mg/L was tested, and 50% niclosamide (WPN) with the concentration of 2 mg/L as well as fresh water were tested as the controls. The molluscicidal effects of 24, 48, 72 h were observed in lab and the field. With the insufflation method and powdering method, 10% LDS with doses of 0.2, 0.4, 0.6, 0.8, 1.0 g/m2 was tested and 50% WPN with the dose of 2 g/m2 as well as fresh water were tested as the controls. The molluscicidal effects of 1, 3, 7 d were observed in lab and the field., Results: At the room temperature of 25-26 degrees C and water temperature of 21-22 degrees C, when exposed for 72 h by the immersion method, the snail death rates of above-mentioned five concentrations of LDS and WPN as well as fresh water were 93.33%, 100%, 100%, 100%, 100%, 100% and 6.67%, respectively in lab. At the field temperature of 18-28 degrees C and water temperature of 18-23 degrees C, when exposed for 72 h by the immersion method, the snail death rates of above-mentioned five concentrations of LDS and WPN as well as fresh water were 91.11%,100%,100%, 100%, 100%, 100% and 3.33%, respectively in the field. When exposed for 7 d by the insufflation method, the snail death rates of five above-mentioned dosages of LDS and WPN as well as fresh water were 90.00%, 94.00%, 96.00% 99.00%, 99.00%, 94.00% and 6.00%, respectively in lab and 80.00%, 82.14%, 88.35%, 90.83%, 96.55%, 92.56% and 4.55%, respectively in the field. When exposed for 7 d by the powdering method, the snail death rates were 74.77%, 88.89%, 94.50%, 90.38%, 92.17%, 90.38% and 4.55%, respectively in the field., Conclusion: LDS has a good molluscicidal effect on Oncomelania hupensis in mountainous areas.