Biological and biochemical studies on Biomphalaria alexandrina snails exposed to some plant extracts having molluscicidal activity / Abu Elyosser Rayan Zahran Ali ; Supervised Abd El rhaman Bashte , Sayed Amin Amer , Fayez Ahmed Bakry

Thesis (PH.D.) - Cairo University - Faculty Of Science - Department Of Zoology

Among ten plants extracts examined , Lactea haw had the strongest molluscicidal activity against Balexandrina snails followed by Euphorbia peplus and Synadenium grantiiMethanol extracts revealed more molluscicidal potency as compared to water suspensionThe sublethal methanol extract concentrations of Euphorbia peplus , Synadenium grantii and Lactea haw induced a comprehensive effect on the mortality rate , growth rate , egg laying capacity of snails , hatchability of snail eggs , and infection with Schistosoma mansoni , miracidial and cercarial productionSignificant increase in mortality rate has been observedThe growth rates of all treated snails were lower than that of the controlEgg laying and reproductive rates of Balexandrina snails were highly suppressedSurvival rates of snails decreased rapidlyThe infectivity of Schistosoma mansoni miracidia was greatly reducedThe prepatent period for snails exposed to sublethal concentrations of the tested plants during their exposure to miracidia has been shortenedCercarial shedding was shorter for tested snailsSusceptibility to miracidial and cercarial infection , larval production and duration of cercarial shedding has been decreasedMortality rates of Smansoni miracidia and cercariae were increasedLactea plant extract was the most effective on the snail activity compared to the other two plant extracts selected

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