Molluscicidal effect of spraying 5% niclosamide ethanolamine salt granules with drones against Oncomelania hupensis in hilly regions / 中国血吸虫病防治杂志

OBJECTIVE@#To establish a snail control approach for spraying chemicals with drones against Oncomelania hupensis in complex snail habitats in hilly regions, and to evaluate its molluscicidal effect.@*METHODS@#The protocol for evaluating the activity of spraying chemical molluscicides with drones against O. hupensis snails was formulated based on expert consultation and literature review. In August 2022, a pretest was conducted in a hillside field environment (12 000 m2) north of Dafengji Village, Dacang Township, Weishan County, Yunnan Province, which was assigned into four groups, of no less than 3 000 m2 in each group. In Group A, environmental cleaning was not conducted and 5% niclosamide ethanolamine salt granules were sprayed with drones at a dose of 40 g/m2, and in Group B, environmental cleaning was performed, followed by 5% niclosamide ethanolamine salt granules sprayed with drones at a dose of 40 g/m2, while in Group C, environmental cleaning was not conducted and 5% niclosamide ethanolamine salt granules were sprayed with knapsack sprayers at a dose of 40 g/m2, and in Group D, environmental cleaning was performed, followed by 5% niclosamide ethanolamine salt granules sprayed with knapsack sprayers at a dose of 40 g/m2. Then, each group was equally divided into six sections according to land area, with Section 1 for baseline surveys and sections 2 to 6 for snail surveys after chemical treatment. Snail surveys were conducted prior to chemical treatment and 1, 3, 5, 7 days post-treatment, and the mortality and corrected mortality of snails, density of living snails and costs of molluscicidal treatment were calculated in each group.@*RESULTS@#The mortality and corrected mortality of snails were 69.49%, 69.09%, 53.57% and 83.48%, and 68.58%, 68.17%, 52.19% and 82.99% in groups A, B, C and D 14 days post-treatment, and the density of living snails reduced by 58.40%, 63.94%, 68.91% and 83.25% 14 days post-treatment relative to pre-treatment in four groups, respectively. The median concentrations of chemical molluscicides were 37.08, 35.42, 42.50 g/m2 and 56.25 g/m2 in groups A, B, C and D, and the gross costs of chemical treatment were 0.93, 1.50, 0.46 Yuan per m2 and 1.03 Yuan per m2 in groups A, B, C and D, respectively.@*CONCLUSIONS@#The molluscicidal effect of spraying 5% niclosamide ethanolamine salt granules with drones against O. hupensis snails is superior to manual chemical treatment without environmental cleaning, and chemical treatment with drones and manual chemical treatment show comparable molluscicidal effects following environmental cleaning in hilly regions. The cost of chemical treatment with drones is slightly higher than manual chemical treatment regardless of environmental cleaning. Spraying 5% niclosamide ethanolamine salt granules with drones is recommended in complex settings with difficulty in environmental cleaning to improve the molluscicidal activity and efficiency against O. hupensis snails.

Effectiveness and cost analysis of two chemical molluscicides in hilly schistosomiasis-endemic regions / 中国血吸虫病防治杂志

Objective To investigate the effectiveness and cost of 50% and 80% wettable powder of niclosamide ethanolamine salt (NESWP) and 26% metaldehyde and niclosamide suspension concentrate (MNSC) in hilly schistosomiasis-endemic regions, so as to provide insights into the selection of chemical molluscicides in hilly regions. Methods In September 2020, a wasteland in Guanshanqiao Village, Yanrui Township, Yushan County of Jiangxi Province was selected as the experimental region, which was sectioned into five blocks and defined as four experimental groups (A1, A2, B, C) and a blank control group (D). 80% NESWP were given at doses of 1 g/m2 and 1.5 g/m2 in groups A1 and A2 using the spraying method, 50% NESWP was given at a dose of 2 g/m2 in Group B using the spraying method, and 26% MNSC was at a dose of 4 g/m2 in Group C using the spraying method, while no chemical treatment was given in Group D. Snail survey was performed using a systematic sampling method before chemical treatment and 1, 3, 7 d and 15 d post-treatment to examine the molluscicidal effect, and all molluscicidal costs were estimated to calculate the cost of chemical treatment per 1 m2 and the cost of the reduction in the mean density of living snails per 1%. Results The highest mortality of snails was 78.95% and the lowest density of living snails was 0.2388 snails/0.1 m2 in the experimental groups within 7 d of chemical treatment, and the highest mortality of snails was 94.74% and the lowest density of living snails was 0.058 0 snails/0.1 m2 7 d post-treatment. There were no significant differences in the snail mortality among the A1, A2, B and C groups 1 (χ2 = 2.250, P > 0.05), 3 (χ2 = 1.779, P > 0.05) or 15 d post-treatment (χ2 = 2.286, P > 0.05), while a significant difference was detected in the snail mortality among the four groups 7 d post-treatment (χ2 = 7.990, P = 0.046). In addition, there were no significant differences in the snail mortality between A1 and A2 groups 1 (χ2 = 0.724, P > 0.05), 3 (χ2 = 0.584, P > 0.05), 7 (χ2 = 0.400, P > 0.05) or 15 d post-treatment (χ2 = 0.251, P > 0.05). The costs of chemical treatment per 1 m2 were 0.58, 0.60, 0.64 Yuan and 0.73 Yuan in groups A1, A2, B and C, and the costs of the mean density of living snail per 1% reduction were 19.29, 20.44, 21.68 Yuan and 23.53 Yuan in groups A1, A2, B and C, respectively. Conclusion 80% NESWP shows a high molluscicidal efficacy and low cost in hilly schistosomiasis-endemic regions.

Molluscicidal effect of immersion with 50% wettable powder of niclosamide ethanolamine salt against Oncomelania hupensis on the soil surface and inside the soil layer in winter / 中国血吸虫病防治杂志

Objective To evaluate the molluscicidal effect of 50% wettable powder of niclosamide ethanolamine salt (WPNES) against Oncomelania hupensis on the soil surface and inside the soil layer by immersion method in winter. Methods O. hupensis snails were placed on the soil surface and 2, 5 cm and 10 cm under the soil layer outdoors in winter, and then immersed in 50% WPNES at concentrations of 1 mg/L and 2 mg/L for 1, 3 d and 7 d, while dechlorinated water served as controls. Snail mortality was observed following immersion with 50% WPNES on the soil surface and inside the soil layer. Results Following immersion with 50% WPNES at concentrations of 2 mg/L and 1 mg/L outdoors in winter, the 3-day corrected snail mortality rates were 98.0% and 76.0% on the soil surface, and the 7-day corrected snail mortality rate was both 100.0%. Following immersion with 50% WPNES at concentrations of 2 mg/L and 1 mg/L outdoors in winter, the 7-day corrected snail mortality rates were 95.5% and 85.6% 2 cm below the soil layer, 66.0% and 6.4% 5 cm below the soil layer. However, the 7-day snail mortality rate swere comparable between the 50% WPNES treatment group (at 2 mg/L and 1 mg/L) and controls 10 cm below the soil layer (both P > 0.05). Conclusion Immersion of 50% WPNES at a concentration of 2 mg/L for 7 days presents a high molluscicidal efficacy against O. hupensis on the soil surface and 5 cm within the soil layers in winter.

Effect and cost-effectiveness of three commonly used molluscicides in largescale field application / 中国血吸虫病防治杂志

Objective To evaluate the effect and cost-effectiveness of three commonly used molluscicides, 4% "Luo-wei" (tea-seed distilled saponins, TDS), 50% niclosamide ethanolamine salt wettable powder (NESWP), and 26% metaldehyde and niclosamide suspension concentrate (MNSC) in large-scale field application, so as to provide the references for formulating the strategy of snail control. Methods The field test and parallel comparison were implemented. A marshland with Oncomelania hupensis snails of the Yangtze River was divided into 4 parts (10 hm2) for the research, and three of them were experimental areas while the last one was a blank control area. The experimental areas were sprayed with 4% "Luo-wei", 50% NESWP and 26% MNSC respectively for 3 times and the interval was 1 week. Seven days after each spraying the effect of snail control was investigated, and the costs of molluscicides, labor, transportation, fuel consumption and mechanical loss were recorded. The cost of each molluscicide, snail mortality, snail density, and the cost of increasing 1% of snail mortality per 100 m2 were analyzed and compared. Results After the first, second and third spraying, the corrected snail mortality rates were 67.34%, 76.55% and 84.60% respectively in the 4% "Luo-wei" group; the corrected snail mortality rates were 64.71%, 75.17% and 83.89% respectively in the 50% NESWP group; the corrected snail mortality rates were 66.55%, 76.27% and 86.67% respectively in the 26% MNSC group. There was no significant difference among the 3 groups in the snail mortality at the same spraying time (χ2 = 1.590, 0.571, 3.238, all P > 0.05) . In addition, along with the increase of the spraying times, the snail mortality of each group was increased significantly compared to that of the control group (χ2 = 79.333, 94.718, 117.020, all P < 0.01) . After the first, second and third spraying, the reduction rates of snail density were 69.82%–86.60% in the 4% "Luo-wei" group, 68.66%–86.55% in the 50% NESWP group, and 71.89%–88.87% in the 26% MNSC group respectively. The decreasing amplitude of the snail density was more than 85% in all the experimental areas after 3 rounds of spraying molluscicide. The snail control costs per 100 hm2 were 19.57, 11.97 Yuan and 10.47 Yuan in the 4% "Luo-wei" group, 50% NESWP group, and 26% MNSC group respectively. After the first, second and third spraying, the costs of increasing 1% of snail mortality per 100 m2 were 0.30, 2.08 Yuan and 2.38 Yuan in the 4% "Luo-wei" group, 0.20, 1.10 Yuan and 1.32 Yuan in the 50% NESWP group, and 0.17, 1.04 Yuan and 0.97 Yuan in the 26% MNSC group respectively, and the cost-effectiveness was the highest at the first spraying in all the three groups. Conclusions The effects of the three molluscicides for snail control are similar, but the efficacy of snail control is reduced as the spraying time increases.

Comparison of molluscicidal cost and effectiveness between 5% niclosamide ethanolamine salt granules and 26% suspension concentrate of metalaldehyde and niclosamide ethanolamine salt / 中国血吸虫病防治杂志

Objective To compare the molluscicidal effects and cost-effectiveness of 5% niclosamide ethanolamine salt granules (NEG) and 26% suspension concentrate of metalaldehyde and niclosamide ethanolamine salt (MNSC) . Methods Two plots with high Oncomelania hupensis snail density were selected as research areas in Nanjing Chemical Industry Zone, and 5% NEG (40 g/m2) and 26% MNSC (40 g/m2) were used by the spraying method for snail control in the two plots, and their molluscicidal effects and cost-effectiveness were investigated and statistically analyzed. Results There was no significant difference between 5% NEG and 26% MNSC in the molluscicidal effects. The cost of 5% NEG was 1.25 times higher than that of 26% MN-SC per ten thousand square meters in snail control. Conclusions The cost of 5% NEG is higher than that of 26% MNSC per ten thousand square meters in snail control. Their molluscicidal effects are similar.

Field molluscicidal effect of water-free formulations of niclosamide ethanolamine salt against Oncomelania hupensis snails in a marshland / 中国血吸虫病防治杂志

To evaluate the molluscicidal effects of various water-free formulations of niclosamide ethanolamine salt against Oncomelania hupensis in the field of marshlands along the Yangtze River.The river beach with O. hupensis snails were selected as the test field in the marshland along the Yangtze River in Pukou District, Nanjing City. A molluscicidal experiment was carried out by the mechanical dusting method with the dustable powder (DP), powder-granule (PG), granule (GR) of niclosamide ethanolamine salt respectively. The snail mortality, corrected mortality, and the reduced rate of snails’ density were parallel compared among DP, PG and GR.On the 3rd day after the dusting, the snail mortality rates were 66.67%, 67.24%, and 66.87% in the DP, PG, and GR groups respectively, on the 7th day after the dusting, the snail mortality rates were 75.36%, 79.73%, and 73.97% in the DP, PG, and GR groups respectively, and there was no significant difference among the groups (χ2 = 0.006, 0.895, both P > 0.05). On the 15th day after the dusting, the snail mortality rates were 86.92%, 72.86%, and 71.43% in the DP, PG, and GR groups respectively, and there was a significant difference among the groups (χ2 = 9.709, P < 0.01). The snail mortality in the DP group was significantly higher than that in the PG, and GR groups. The curves of the snail corrected mortality and reduced rate of snails’density presented steadily rising trends in the DP group, but presented falling trends in the PG and GR groups on the 15th day after the dusting.The molluscicidal effect of DP is stable and effective in the marshland along the Yangtze River, but the drift of the powder is still not effectively controlled. It is necessary that the different dosage forms are perfected.

Comparison of molluscicidal cost and effectiveness between 5% niclosamide ethanolamine salt granules and 26% suspension concentrate of metalaldehyde and niclosamide ethanolamine salt / 中国血吸虫病防治杂志

Objective To compare the molluscicidal effects and cost-effectiveness of 5% niclosamide ethanolamine salt granules (NEG) and 26% suspension concentrate of metalaldehyde and niclosamide ethanolamine salt (MNSC) . Methods Two plots with high Oncomelania hupensis snail density were selected as research areas in Nanjing Chemical Industry Zone, and 5% NEG (40 g/m2) and 26% MNSC (40 g/m2) were used by the spraying method for snail control in the two plots, and their molluscicidal effects and cost-effectiveness were investigated and statistically analyzed. Results There was no significant difference between 5% NEG and 26% MNSC in the molluscicidal effects. The cost of 5% NEG was 1.25 times higher than that of 26% MN-SC per ten thousand square meters in snail control. Conclusions The cost of 5% NEG is higher than that of 26% MNSC per ten thousand square meters in snail control. Their molluscicidal effects are similar.

Molluscicidal effects of different formulations of niclosamide ethanolamine salt in marshlands / 中国血吸虫病防治杂志

Objective To evaluate the molluscicidal effects of different formulations of niclosamide ethanolamine salt in marshlands. Methods The molluscicidal effects of spraying with 25% suspension concentrate of niclosamide ethanolamine salt (25% SCN) and 50% wettable powder formulation of niclosamide ethanolamine salt (50% WPN), and dusting with 4% niclosamide ethanolamine salt dustable powder (4% DP) for controlling Oncomelania hupensis snails were investigated and compared in the fields, and the cost-effectiveness was analyzed. Results The corrected mortalities and the reduced rates of density of snails were 54.37%, 91.70%, 92.76%, 79.50%, and 59.55%, 95.93%, 97.63%, 94.15%, respectively, on 3, 7, 15, 30 d after spaying with 25% SCN, those on 3, 7, 15, 30 d after dusting with 4% DP were 59.10%, 91.83%, 95.56%, 93.34% and 65.03%, 94.93%, 97.61%, 97.28%, respectively; and those on 3, 7, 15, 30 d after spraying with 50% WPN were 76.29%, 91.68%, 93.12%, 81.59% and 81.24%, 97.02%, 97.84%, 95.27%, respectively. The cost of spraying with 25% SCN was 0.21 Yuan/m2, that of dusting with 4% DP was 0.39 Yuan/m2, and that of spraying with 50% WPN was 0.23 Yuan/m2 for snail control in the marshland. The cost of reduced one percentage of the corrected mortalities and the density of snails in controlling snails by 25% SCN, 4% DP and 50% WPN on 15 d were 22.68, 40.63, 25.17 Yuan and 21.54, 39.78, 23.95 Yuan, respectively. Conclusions The three different formulations of niclosamide are reliable and effective for snail control in marshlands. There are some differences among the different molluscicides in start time, pharmacodynamic characteristics, spraying methods in the field, cost of snail control, and influencing factors. Therefore, we need reasonably select the suitable molluscicides according to the environmental characteristics and working condition.

Molluscicidal effects of different formulations of niclosamide ethanolamine salt in marshlands / 中国血吸虫病防治杂志

Objective To evaluate the molluscicidal effects of different formulations of niclosamide ethanolamine salt in marshlands. Methods The molluscicidal effects of spraying with 25% suspension concentrate of niclosamide ethanolamine salt (25% SCN) and 50% wettable powder formulation of niclosamide ethanolamine salt (50% WPN), and dusting with 4% niclosamide ethanolamine salt dustable powder (4% DP) for controlling Oncomelania hupensis snails were investigated and compared in the fields, and the cost-effectiveness was analyzed. Results The corrected mortalities and the reduced rates of density of snails were 54.37%, 91.70%, 92.76%, 79.50%, and 59.55%, 95.93%, 97.63%, 94.15%, respectively, on 3, 7, 15, 30 d after spaying with 25% SCN, those on 3, 7, 15, 30 d after dusting with 4% DP were 59.10%, 91.83%, 95.56%, 93.34% and 65.03%, 94.93%, 97.61%, 97.28%, respectively; and those on 3, 7, 15, 30 d after spraying with 50% WPN were 76.29%, 91.68%, 93.12%, 81.59% and 81.24%, 97.02%, 97.84%, 95.27%, respectively. The cost of spraying with 25% SCN was 0.21 Yuan/m2, that of dusting with 4% DP was 0.39 Yuan/m2, and that of spraying with 50% WPN was 0.23 Yuan/m2 for snail control in the marshland. The cost of reduced one percentage of the corrected mortalities and the density of snails in controlling snails by 25% SCN, 4% DP and 50% WPN on 15 d were 22.68, 40.63, 25.17 Yuan and 21.54, 39.78, 23.95 Yuan, respectively. Conclusions The three different formulations of niclosamide are reliable and effective for snail control in marshlands. There are some differences among the different molluscicides in start time, pharmacodynamic characteristics, spraying methods in the field, cost of snail control, and influencing factors. Therefore, we need reasonably select the suitable molluscicides according to the environmental characteristics and working condition.

Effect and cost-effectiveness of three commonly used molluscicides in largescale field application / 中国血吸虫病防治杂志

Objective To evaluate the effect and cost-effectiveness of three commonly used molluscicides, 4% "Luo-wei" (tea-seed distilled saponins, TDS), 50% niclosamide ethanolamine salt wettable powder (NESWP), and 26% metaldehyde and niclosamide suspension concentrate (MNSC) in large-scale field application, so as to provide the references for formulating the strategy of snail control. Methods The field test and parallel comparison were implemented. A marshland with Oncomelania hupensis snails of the Yangtze River was divided into 4 parts (10 hm2) for the research, and three of them were experimental areas while the last one was a blank control area. The experimental areas were sprayed with 4% "Luo-wei", 50% NESWP and 26% MNSC respectively for 3 times and the interval was 1 week. Seven days after each spraying the effect of snail control was investigated, and the costs of molluscicides, labor, transportation, fuel consumption and mechanical loss were recorded. The cost of each molluscicide, snail mortality, snail density, and the cost of increasing 1% of snail mortality per 100 m2 were analyzed and compared. Results After the first, second and third spraying, the corrected snail mortality rates were 67.34%, 76.55% and 84.60% respectively in the 4% "Luo-wei" group; the corrected snail mortality rates were 64.71%, 75.17% and 83.89% respectively in the 50% NESWP group; the corrected snail mortality rates were 66.55%, 76.27% and 86.67% respectively in the 26% MNSC group. There was no significant difference among the 3 groups in the snail mortality at the same spraying time (χ2 = 1.590, 0.571, 3.238, all P > 0.05) . In addition, along with the increase of the spraying times, the snail mortality of each group was increased significantly compared to that of the control group (χ2 = 79.333, 94.718, 117.020, all P < 0.01) . After the first, second and third spraying, the reduction rates of snail density were 69.82%–86.60% in the 4% "Luo-wei" group, 68.66%–86.55% in the 50% NESWP group, and 71.89%–88.87% in the 26% MNSC group respectively. The decreasing amplitude of the snail density was more than 85% in all the experimental areas after 3 rounds of spraying molluscicide. The snail control costs per 100 hm2 were 19.57, 11.97 Yuan and 10.47 Yuan in the 4% "Luo-wei" group, 50% NESWP group, and 26% MNSC group respectively. After the first, second and third spraying, the costs of increasing 1% of snail mortality per 100 m2 were 0.30, 2.08 Yuan and 2.38 Yuan in the 4% "Luo-wei" group, 0.20, 1.10 Yuan and 1.32 Yuan in the 50% NESWP group, and 0.17, 1.04 Yuan and 0.97 Yuan in the 26% MNSC group respectively, and the cost-effectiveness was the highest at the first spraying in all the three groups. Conclusions The effects of the three molluscicides for snail control are similar, but the efficacy of snail control is reduced as the spraying time increases.

Vasorelaxant effect and mechanism of niclosamide ethanolamine on rat coronary artery / 中国比较医学杂志

Objective To investigate the vasorelaxant effect and possible mechanism of niclosamide ethanolamine (NEN)on isolated rat coronary artery(RCA). Methods Wire myograph was used to record myogenic tone of vessels. The vasorelaxant effect of NEN was studied in RCA precontracted with either KCl or U46619. Study of related inhibitors was performed to investigate possible involvement of potassium channels and the mitogen-activated protein kinase(MAPK) signaling pathway in vasorelaxation. The effect of NEN on Ca2+mobilization was determined by observing vasoconstrictor-induced contractions in tissue solution deprived of Ca2+followed by Ca2+restoration. Results NEN(0.5-3.0 μmol/L) relaxed RCA precontracted with KCl or U46619 in a concentration-dependent manner. MAPK inhibitors(PD98059 and SB239063)reduced the relaxant effect of NEN,while the potassium-channel blockers(tetraethylamine,4-aminopyridine, BaCl2,and glibenclamide)did not significantly affect relaxation. NEN specifically inhibited the contraction component dependent on extracellular Ca2+influx in vessels stimulated with KCl and U46619, with a negligible effect on the component dependent on intracellular Ca2+release. Conclusions NEN exhibits vasodilator properties in RCA. Inhibition of extracellular Ca2+influx and activation of the MAPK signaling pathway may be involved in NEN-induced RCA vasorelaxation.

Effects and cost of four formulations of niclosamide ethanolamine salt in On-comelania hupensis snail control in field / 中国血吸虫病防治杂志

Objective To investigate the effects and cost of four formulations of niclosamide ethanolamine salt in Oncomela-nia hupensis snail control in the field in marshland and lake regions,so as to provide the evidence for drawing up the plan of mol-luscicide using in schistosomiasis endemic areas. Methods One drainage channel and one channel without water in the same area with snails in Jiangling County,Jingzhou City were selected as the research fields. The drainage channel was divided into 9 sections,except one section as a blank control group where the natural death rate of snails was observed only,and the remaining 8 sections were taken as the observation groups,where different dosages of 4％niclosamide ethanolamine salt powder,5％ni-closamide ethanolamine salt granules,25％ niclosamide ethanolamine salt suspending agent,26％ metaldehyde and ni-closamide ethanolamine salt suspending agent,and 50％niclosamide ethanolamine salt wettable powder were used re-spectively. The channel without water were divided into 4 sections,except one section as a blank control group,the oth-er 3 segments were taken as the observation groups,where 4％niclosamide ethanolamine salt powder,5％niclosamide ethanolamine salt granules,and 50％ niclosamide ethanolamine salt wettable powder were used respectively. Before and after spraying molluscicide for 7 days and 15 days,the system sampling method was used to observe the effects of snail control. Meanwhile,the unit cost method was used to calculate the costs of the different mulluscicide formulations abovementioned in unit area(1 m2). Results In the field at the drainage channel,the snail mortality rates of the groups spraying 4％niclosamide ethanolamine salt powder(50 g/m2),5％niclosamide ethanolamine salt granules(40 g/m2),25％ niclosamide ethanolamine suspending agent,26％ metaldehyde and niclosamide ethanolamine salt sus-pending agent,and 50％niclosamide ethanolamine salt wettable powder(2 g/m2 and 4 g/m2)for 7 days were 79.52％-97.87％,while the rates after spraying for 15 days were 71.00％-96.30％,and compared with those before spraying, the differences were statistically significant(all P<0.01). For the groups spraying with 2 g/m2 or 4 g/m2 suspending agent as well as wettable powder for 7 days,the snail mortality rates were significantly different(both P<0.05). In the field at the channel without water,the snail mortality rates of the 3 observation groups after spraying molluscicide for 7 days were 97.14％-100％,while for 15 days were 94.32％-100％,and compared with the rates before spraying,all the differences were statistically significant(all P<0.01). The unit costs per 1 m2 of the molluscicide abovementioned were ranged from 0.280 Yuan to 0.416 Yuan. Conclusions In marshland area inside embankment,the molluscicide formulations of the powder and granule are suitable for the environments without water or with instability water level , while the molluscicide formulations of the suspended agents and wettable powder are suitable for the water environment. Though the unit cost of powder is the lowest,the molluscicide in this formulation flies away seriously.

Molluscicidal effect of suspension concentrate of niclosamide ethanolamine salt / 中国血吸虫病防治杂志

Objective To evaluate the molluscicidal effect of suspension concentrate of niclosamide ethanolamine salt(SC-NE)against Oncomelania hupensis snails in laboratory and field. Methods The experiment of SCNE against the snails by using the immersing and spraying methods was performed in laboratory and field,with control groups of wettable powder of ni-closamide ethanolamine salt(WPN). Results In the laboratory,LC50(s) of SCNE for 24,48 h and 72 h by using the immersion method were 0.0926,0.0629 mg/L and 0.0549 mg/L,respectively. The mortality rates of snails for 24,48 h and 72 h by using the immersion method were all 100％ with the concentrations of 0.25 mg/L. The mortality rates of snails were all 100％ while spraying SCNE for 3 d in the laboratory with the concentrations of 0.25 g/m2. In Jiangling County,except 0.5 g/m3 SCNE immers-ing the snails for 24 h,the mortality rates of snails by using SCNE with the immersing method were all 100％. While the concen-tration of SCNE was 0.5 g/m3 or above,the mortality rates were all 100％after the use of it with the immersion method for 2 d in Gong'an County. In Jiangling County,the mortality rates of snails by using SCNE 0.5 g/m3 for 1 d,3 d,and 7 d with the spray-ing method were 87.5％,92.82％and 97.40％respectively. While the concentration of SCNE was 0.5 g/m3,the mortality rates were 85.94％,86.78％and 94.21％respectively after the use of it with the spraying method for 1 d,3 d,7 d in Gong'an Coun-ty,and the molluscicidal effect of SCNE(1.0 g/m2)was higher than that of WPN. Conclusion SCNE has a high molluscicidal effect in the laboratory and field,and it is a novel and simple formulation of niclosamide.

Molluscicidal effect of niclosamide ethanolamine salt powder - granula against Oncomelania hupensis / 中国血吸虫病防治杂志

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.

Oncomelania hupensis snail control effects of molluscicides with different formulations in field in marshland and lake regions / 中国血吸虫病防治杂志

Objective To observe the Oncomelania hupensis snail control effects of molluscicides with different formula?tions in the ditch with unstable water level in field of marshland and lake areas,so as to provide the evidence for formulating the prevention strategies. Methods A drainage channel with O. hupensis snails in Jiangling County,Jingzhou City were selected as the study field,then it was divided into 6 segments,except 1 segment was treated as the blank control group for observing the natural mortality rate of the snails,the other 5 segments were treated as observation groups,where 4% niclosamide ethanol?amine salt powder,5%niclosamide ethanolamine salt granule,25%suspension concentrate of niclosamide ethanolamine salt, 26% suspension concentrate of metaldehyde and niclosamide ethanolamine salt,50% niclosamide ethanolamine salt wettable powder were applied respectively. Before and after the mollusciciding,the snail surveys were carried out through the systematic sampling method,and the short?and long?term effects of snail control were observed,and the mortality rates of the snails on the slope above the water level and those below the water level were compared. Results When 7 d and 15 d after mullusciciding, the mortality rates of snails on the slope above the water level in each observation group were 79.52%-97.87% and 90.43%-96.30%,respectively,when compared with those before mollusciciding,all the differences were statistically significant(all P<0.01). When 7 d after mullusciciding,the mortality rates of snails below the water level in each observation group were 17.11%-50.00%,which were all lower than those of the snails on the slope above the water level in the corresponding groups(all P<0.05);when 15 d after mullusciciding,the rates were 9.43%-95.24%,and those in 25%suspension concentrate of niclosamide ethanolamine salt,26%suspension concentrate of metaldehyde and niclosamide ethanolamine salt,50%niclosamide ethanol?amine salt wettable powder groups were all lower than those of the snails on the slope above the water level in the corresponding groups(all P<0.01). Compared with the densities of living snails before mollusciciding,those 6 months after mollusciciding in each observation group decreased by 70.21%-78.98%. Conclusions The molluscicides in the formulation of powders and granule are suitable for both the snail environment with or without water,while those in the formulation of suspension agents and wettable powders are suitable only for environments with water.

Effects of molluscicides at different environments on Oncomelania hupensis snail control in Danyang City / 中国血吸虫病防治杂志

Objective To evaluate the effects of continuous application of niclosamide ethanolamine salt on Oncomelania hu-pensis snail control in a marshland,river and channel. Methods The Beiwei marshland in Houxiang Town,the Xiaoliang River in Lingkou Town and Laomiao channel in Yunyang Town in Danyang City were selected as study sites,and 4%niclosamide etha-nolamine salt and 26%niclosamide powder were used to kill the snails. Based on the historical records and field investigations, the effects of continuous application of niclosamide ethanolamine salt on snail control were evaluated. Results Compared with the first time of snail repetition,the snail areas decreased by 82.80%,63.14%and 70.00%in the Beiwei marshland,Xiaoliang River and Laomiao channel,respectively,in 2013. There was a positive correlation between the area and density of snails(r=0.931, 0.975 and 0.916,respectively;all P values < 0.05). The average densities of living snails decreased significantly by 92.34%, 87.91%and 97.66%,respectively. There was a negative correlation between the corrected mortality of snails and the average densi-ty of living snails in the following year,and a negative correlation between the reduction rate of living snail density and the average density of living snails in the following year. Conclusion Molluscicides plays an important role in compressing the snail area,re-ducing the snail density,and controlling the schistosomiasis transmission.

Molluscicidal effect of 5%niclosamide ethanolamine granules against Onco-melania hupensis in a marshland field / 中国血吸虫病防治杂志

Objective To investigate the molluscicidal effect of 5%niclosamide ethanolamine granules against Oncomela-nia hupensis in a marshland field. Methods The 5%niclosamide ethanolamine granules were sprayed at a dose of 40 g/m2 on 3 snail-breeding marshlands in Yangzhong City of Jiangsu Province to assess its field molluscicidal actions while 26%suspension concentrate of metaldehyde and niclosamide MNSC) at a dose of 4 g/m2 and fresh water served as controls. Results After seven days spraying, 5%niclosamide ethanolamine granules resulted in a of snail mortal85.42%ity while the mortality rates of snails were 82.35% and 2.86% in the MNSC and water control groups respectively. Conclusion 5% niclosamide ethanol-amine granules exhibit a high molluscicidal activity which is suitable to be used in the mashland.

Molluscicidal effects of 3 molluscicides by spraying and poudrage methods in dry season / 中国血吸虫病防治杂志

Objective To evaluate the effects of 3 molluscicides namely 5%niclosamide ethanolamine granules,4%“Luo-wei”(Tea-seed distilled saponins,TDS)and 50%wettable powder of niclosamide ethanolamine salt(WPN)by spraying and pou-drage methods in marshland and lake regions in dry season. Methods An environment with a high snail density was chosen as the experimental field,then the spraying and poudrage experiments were carried out in the field to assess the molluscicidal effects of 5%niclosamide ethanolamine granules,TDS and WPN delivered by spraying and poudrage methods with a concentration of 30, 6 and 2 g/m2,respectively,and the molluscicidal effects of the 3 drugs by the two methods were evaluated and compared in differ-ent time. Results After the delivery for 15 d,the adjusted snail death rates of the 5%niclosamide ethanolamine granules,TDS and WPN in the spraying experiment were 79.00%,82.29%and 84.83%,respectively,and those in the poudrage experiments were 97.42%,95.27% and 96.62%,respectively. Conclusion The molluscicidal effect of poudrage method is better than the spraying method,and the former is worthy of further extension and application in the marshland in dry season.

Comparison of field molluscicidal effects of four molluscicides / 中国血吸虫病防治杂志

Objective To compare the field molluscicidal effects of 25%suspension concentrate of nielosamide ethanolamine salt(SCNE),50% wettable powder of niclosamide ethanolamine salt(WPN),40% META-Li and 50% Rongbao powder,so as to provide scientific basis for choosing the safe and highly effective molluscicide in field.Methods Four snail habitats with the similar snail status were selected and sprayed with the four molluscicides mentioned above,respectively.Then the snail status in the four fields was surveyed 3,7 and 17 d after the spraying and the moiluscicidal effects of difierent molluscieides were cornpared.Results The corrected mortalities of snails in the field sprayed with SCNE 3,7 and 17 d afterthe spraying were the hiishest among the four fields,with the rates of 93.13%,91.85% and 85.28%,respectively.Conclusion SCNE has a high molluseieidal effect in the field and can be further used in snail-infested areas.

Observation on frequency and effect of dusting molluscicide in irrigation canals / 中国血吸虫病防治杂志

Objective To study a new method and technical specification for Oncomelania snail control in irrigation canals.Methods Four percent niclosamide ethanolamine salt dustable powder was dusted in a test canal three times continuously,and a control canal was set up at the same time.The molluscicidal frequency and effect of niclosamide ethanolamine salt powder was observed and the results,including the change of living snail frames,average density of living snails and mortality of snails,were analyzed.Results Between the third and fifteenth day after the first dusting in the test canal,the reduction rate of the density of snails was more than 90% and after the second and third dusting,the reduction rate was more than 99%.For the average rates of living snail frames and mortality of snails,there were significant differences between the first dusting and later two dustings,while there was no significant difference between the second dusting and the third dusting.On the thirtieth and ninetieth day after the third dusting,the effect of snail control was still satisfactory.There were significant differences between the test canal and control canal about all the observation indexes.Conclusion The application of 4% niclosamide ethanolamine salt dustable powder is efficient in the snail control in irrigation canals,and the suitable frequency of dusting is 2 or 3 times.