The present work evaluates the molluscicidal activities of certain plant extracts (water suspension, Cold water, Boiled water, methanol, ethanol, acetone and chloroform extract) against Biomphalaria alexandrina. Preliminary screening tests conducted on 10 plant species that belong to 9 different families showed that the higher potency was recorded for Agave celsii, Ammi visnaga and Chenopodium ambrosioices. Also, exposure of B. alexandrina snails to plant extracts led to a significant reduction in the survival and in the growth rates as well as in their infection with Schistosoma mansoni miracidia. The results obtained also revealed that the glucose concentration increased in haemolymph, while soft tissue glycogen and protein contents were decreased. The activities of Hexokinase, pyruvatekinase and lactate dehydrogenase were also significantly reduced in response to treatment, while adenosine triphosphatase (ATPase) activity of the tissue of the snails was significantly increased.
Key words: B. alexandrina - Schistosoma mansoni plant molluscicides