Molluscicidal effect of niclosamide ethanolamine salt powder - granula against Oncomelania hupensis

Abstract

To evaluate the molluscicidal effect of niclosamide ethanolamine salt powder-granula (PG) against Oncomelania hupensis. 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. 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). 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.