Schistosoma mansoni and fascioliasis are worldwide parasitic diseases infecting 83 and 17 million people respectively causing significant
morbidity and mortality. The present work was carried out to evaluate the molluscicidal activities of the ethanolic extract of three plant
species namely Euphorbia aphylla, Ziziphus spina-christi and Enterolobium contortisiliquum against Biomophalaria alexandrina and
Lymnaea cailliaudi (natalensis), the snails intermediate hosts of Schistosoma mansoni and Fasciola respectively. The highest
molluscicidal activity was recorded for Euphorbia aphylla on both snails’ species. The least activity was recorded for Enterolobium
contortisiliquum which gave negative results against both snail species up to1000 ppm. The LC50 and LC90 of the ethanolic extract of
Euphorbia aphylla against Biomophalaria alexandrina snails were 87.6 ppm and142.5ppm respectively while the LC50 and LC90 of
Euphorbia aphylla against Lymnaea cailliaudi snails were 0.66 ppm and 0.88 ppm respectively. The LC50 and LC90 of Ziziphus spinachristi
ethanolic extract against Lymnaea cailliaudi snails were 311ppm and 500 ppm respectively. However it showed no molluscicidal
activity againist B. alexandrina snails up to 1000 ppm. The histopathological changes in hermaphrodite gland of B. alexandrina and
Lymnaea cailliaudi snails 2 weeks post exposure to LC25 of the ethanolic extract Euphorbia aphylla and the histopathological effect of LC25
of the ethanolic extract Ziziphus spina- christi on Lymnaea cailliaudi snails were studied. Degenerative changes in hermaphrodite acini
and their contents of ova and sperms were observed. The purification of active compounds present in Euphorbia aphylla and Ziziphus
spina- christi plants may offers an alternative tool for the control of snails’ intermediate hosts of Schistosoma mansoni and Fasciola.
Further investigations for Enterolobium contortisiliquum may increase its potential use as plant molluscicide are recommended