Molluscicidal Activity of Some Selected Plants on Freshwater Snail Lanistes Ovum

Abstract

Schistosomiasis is considered as one of the most important trematode disease of man. The most important goal of the present study is to use the natural plants as cheaper and available sources for snail control. Snails’ species are associated with transmission of parasitic disease as intermediate host. This research was conducted to determine the Molluscicidal activities of some selected plants leaves extracts against freshwater snail Lanistes ovum. The plants include; Khaya senegalensis, Senna occidentalis and Vernonia amygdalina. The results of  qualitative Phytochemical screening conducted on the plants revealed the presence of different phytochemical compounds which such as Tannins, Saponins, Flavonoids, Cardiac glysides, Alkaloides and Inulin. The results of toxicity studies of the plants conducted against the experimental snails indicated that, there was significant negative correlation between LC values and exposure periods. Thus with increase in exposure periods the LC₅₀ values decreased from 395.58 mg/L (24 hours) to 216.48mg/L (72 hours and 96 hours was 100%) in Vernonia amaydina, Khaya senegalensis and Senna occidentalis. The LC₉₀ (24 hours) doses of these plants against snails exhibited no mortality in non-target organism, Tilapia fish (Tilapia zilli). The LC₅₀ at exposure period of 96 hours was the most effective treatment among all other exposure periods; 24 hours, 48 hours, 72 hours and 96 hours. The toxicity was both timed as well as dose-dependent. There was significant negative correlation between LC₅₀ values and exposure periods. Thus, with increase in exposure periods LC₅₀ values decreased. In case of the toxicity of S. occidentalis on L. ovum, the LC₅₀ values decreased from 83.67 mg/L after 24 hours, 57.63 mg/L after 48 hours to 52.71mg/L after 72 and 96 hours. In case of Khaya. senegalensis toxicity on L. ovum, the LC₅₀ values decreased from 614.288 mg/L after 24 hours, 246.22 mg/L after 48 hours and 163.11mg/L after 72 hours and 96 hours was 100% against freshwater snails. However, the toxicity of V. amygdalina on exposed snails indicated that, the LC₅₀ values decreased from 395.58 mg/L after 24 hours, 285.84 mg/L after 48 hours and 216.48mg/L after 72 hours and 96 hours was 100% against freshwater snails.The leaves extract of these plants were toxic against the snail and can be of great help in the management of intestinal schistosomiasis. The study provides considerable scope in exploiting local indigenous resources as snails' molluscicidal agents.