Molluscicidal Effect of Croton tiglium Seed and Leaf Extracts on Freshwater Snails (Oncomelania hupensis quadrasi Mollendorf)

Abstract

The molluscicidal effect of Croton tiglium seeds and leaves on Oncomelania hupensis quadrasi,an intermediate host of Schistosoma japonicum was studied. Acclimatized snails were exposed to various concentrations of organic and aqueous extracts of C. tiglium seeds and leaves for 24-, 72-, and 120- hours. LC50 and LC90 were determined using probit analysis. Seed extracts of Croton tiglium proved to be more effective than the aqueous leaf extract. Organic extract of the seeds was the most effective molluscicide based on the mortality rates of the snail. Organic extract of Croton tiglium seeds had the lowest LC50 and LC90. The response of the snail was time and dose dependent. As duration of exposure and concentration increased, mean percent mortality also increased. The histopathological effect of the seed and leaf extracts on the foot muscle and hepatopancreas of Oncomelania hupensis quadrasi revealed that the toxin in the seed and leaf extracts of Croton tiglium was systemic, as well as contact poison. Histological changes of the foot revealed epithelial damage and increase in the number of amoebocytes and mucous cells. Microscopic examination of the hepatopancreas also showed membrane damage. Digestive cells became highly vacuolated and calcium cells increased.