Longitudinal study on molluscicidal effect of suspension concentrate of niclosamide in marshland / 中国血吸虫病防治杂志

ABSTRACT

Objective To evaluate the long-term molluscicidal effect of suspension concentrate of niclosamide (SCN) spraying in marshland regions of the Yangtze River. Methods A marshland with Oncomelania snails in Yangzhong City, Jiangsu Province, was selected as the study spot, and a dose of 6-8 g/m2 of SCN was sprayed yearly for four successive years, and the status of snails was investigated. Results From 2004 to 2007, the average densities of living snails were 6.00, 4.25, 2.04, 1.95 snails/0.1 m2, respectively before the use of molluscicide, and 0.86, 0.86, 0.23, 0.16 snails/0.1 m2, respectively after that. The average densities of living snails before and after the use of molluscicide reduced year by year, and the reduction rates of average densities of living snails were 85.67%, 79.76%, 88.49% and 91.78%, respectively from 2004 to 2007. The rate of frames with snails after the use of molluscicide was 73.46% in 2007, with a reduction rate of 86.85% compared with 9.66% of that before the use of molluscicide in 2004, and the average density of living snails reduced from 6.00 snails/0.1 m2 to 0.16 snails/0.1 m2, with a reduction rate of 97.33%. Conclusions After the spraying for four successive years, the density of snails reduces significantly and the molluscicidal effect is stable and reliable. SCN is a formulation of molluscicide for long-term application in marshland regions.