Evaluation of the molluscicidal activity of some local plants

Molluscicidal screening of aqueous suspensions of 79 local plants belonging to 34 families was carried out. Two different snail species; Biomphalaria alexandrina and Lymnaea caillaudi, the intermediate host of Schistosoma mansoni and Fasciola hepatica respectively in Egypt were used in this study. Because of the high molluscicidal activity of Dizygotheca elegantissima [Araliaceae] and Agave decipiens [Agavaceae]. [The LC90 values for D. elegantissima were 100 and 80 ppm and for A. decipiens 180 and 170 ppm against the two snail species respectively after 24 hr of exposure], the two plant species were examined in greater detail. The acetone, methanol, ethyl acetate, and chloroform extracts of D. elegantissima and only the methanol extract of A. decipiens showed promising activity against Biomphalaria alexandrina snails. Preliminary phytochemical screening of both plants revealed the presence of sterols and / or triterpenes, flavonoids, carbohydrates, and/or glycosides as well as saponins. Tannins were only found in D. elegantissima while alkaloids and /or nitrogenous bases were absent in both plants. The effects of some environmental conditions on the potency of the two plants has been studied