ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Objective To understand whether the breeding time of snails influences the evaluation on molluscicidal efficacy against Oncomelania snails so as to make a standardization of methods for screening molluscicides in laboratory. Methods Snails collected from the endemic areas in Nanjing and Tongling cities bred for 1,6,11,16,21.31,61 and 91 days respectively, and then were immersed in 1.000 0,0.500 0,0.250 0,0.125 0,0.062 5 and 0.031 3 mg/L solution of niclosamide for 24 and 48 hours at 25℃ in laboratory. Results One hundred percent killing rate was achieved in the groups of the snails bred for 1 - 11 days and immersed in 1.0 mg/L niclosamide for 24 hours. The LC_(50) concentrations of snails collected from Nanjing, Jiangsu Province and immersed for 24 hours varied from 0.094 7 to 0.133 9 mg/L, and for 48 hours from 0.071 8 to 0.092 6 mg/L.Those of snails collected from Tongling, Anhui Province for 24 hours varied from 0.082 5 to 0.103 9 mg/L, and for 48 hours from 0. 071 8 to 0.082 5 mg/L. The molluscicidal effect was unstable in the groups of snails bred for more than 16 days. There was a significant difference (X_(Nanjing24 h)~2 = 22.26,P