New Possible Molluscicides fromCalendula micrantha officinalisandAmmi majus: II. Molluscicidal, Physiological, and Egg-Laying Effects againstBiomphalaria alexandrinaandBulinus truncatus

In the present study, the effects of CuSo4and crude extracts of the different parts ofCalendula micrantha officinalisandAmmi majus,i.e., leaves, stems, roots, and flowers, on adultBiomphalaria alexandrinaandBulinus truncatuswere investigated. Generally, leaves and flowers of both plants exhibited marked potency in killing the snail vectors of schistosomiasis. The recorded LC50and LC90values showed thatC. officinaliswas more toxic to both snails thanA. majus,andB. truncatusare more sensitive to the extracts of both plants thanB. 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 ofA. majushave 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.