[Molluscicidal effects of different formulations of niclosamide ethanolamine salt in marshlands].

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 effect of niclosamide ethanolamine salt powder - granula against Oncomelania hupensis].

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 ethanolamine 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 between 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, P < 0.01). The LC50 (s) of 1d, 3 d, 7 d after dusting the molluscicide also showed that the molluscicidal effects of DP were better than PG. The corrected mortality rates were 91.71%, 92.91%, 90.57%, 85.33% and 71.09%, 90.11%, 90.13%, 85.26% on 3 d, 7 d, 15 d, 30 d after dusting with 4% PG and 4% DP, respectively, in the fields. Statistics showed that the mortality rates of snails were higher on 3 d, 7 d after dusting with PG than DP (χ23 d = 731.57, χ27 d = 25.90, P < 0.01), but there were no significant differences between PG and DP on 15d, 30d after dusting (χ215 d = 0.53, χ230 d = 0.01, P > 0.05). 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.