New possible molluscicides from Calendula micrantha officinalis and Ammi majus. II. Molluscicidal, physiological, and egg-laying effects against Biomphalaria alexandrina and Bulinus truncatus.

In the present study, the effects of CuSo4 and crude extracts of the different parts of Calendula micrantha officinalis and Ammi majus, i. e., leaves, stems, roots, and flowers, on adult Biomphalaria alexandrina and Bulinus truncatus were investigated. Generally, leaves and flowers of both plants exhibited marked potency in killing the snail vectors of schistosomiasis. The recorded LC50 and LC90 values showed that C. officinalis was more toxic to both snails than A. majus, and B. truncatus are more sensitive to the extracts of both plants than B. alexandrina. Snails that are produced from snails previously exposed to low doses were more sensitive to the tested extracts, which may give primary indication of no possibility of inherited resistance. Moreover, prolonged exposure to the sublethal concentrations of A. majus have a definite lethal effect on the egg laying and longevity of both snails. Also, treatment with sublethal doses of both plants clearly inhibited the transaminase activity (ALAT, ASAT), diminished the total protein content, and increased markedly total lipid contents in the hemolymph of both snails.