Molluscicidal activities of certain pesticide and their mixtures against Biomphalaria alexandrina

In this study, Biomphalaria alexandrina snails were collected from irrigation canals at Giza Governorate and maintained on fresh lettuce leaves under suitable laboratory conditions. Niclosamide and uccmaluscide proved to be the most effective compounds, followed by copper sulfate. This was followed by anilofos, isoprothiolane and fluazifop-P-butyl. Moreover, butachlor herbicide was the least potent compound. In general, the specific molluscicides showed more efficiency than the conventional tested herbicides and fungicides on the treated snails. Pre-exposure to 1/10 LC50 of anilofos, butachlor and isoprothiolane showed synergistic effects to uccmaluscide. However, the same treatment with 1/10 LC50 of fluazifop-P-butyl, isoprothiolane and butachlor gave an additive effect to copper sulfate and niclosamide on the treated snails. Data indicated that when butachlor, anilofos, fluazifop-P-butyl or isoprothiolane added to copper sulfate at ratios of 10:40 and 20:30 of LC50 as well as anilofos when added to copper sulfate at 30:20 showed synergism in activity against snails. On the contrary, the tested mixtures with niclosamide resulted in an antagonistic action, while they showed synergistic effect. Isoprothiolane-uccmaluscide mixture at a ratio of 40:10 of LC50 showed an additive effect on the snails. The determination of niclosamide by gas chromatography indicated that niclosamide showed relatively slower degradation either in case of niclosamide or its mixture with butachlor. Meanwhile, its mixture with anilofos or fluazifop-p-butyl or isoprothiolane showed a rapid degradation

Susceptibility of biomphalaria Alexandria to the plant azole pinnate and some herbicides in relation to infection with schistosoma mansoni miracidia

Molluscicidal activity of the herbicides 2,4-D and Graminol as well as both extracts and dry powder of the plant Azolla pinnata were evaluated against B. alexandrina snails. It was observed that 2,4-D proved to be the most toxic compound among the tested ones, showing LC90 of 52 ppm after 24 hours of exposure. Ethanol extract of Azolla showed the highest molluscicidal activity against the tested snails compared with the other extracts and dry powder [LC90 = 3300 ppm]. Ethanol extract at 6600 ppm after 3 hours of exposure killed 100% and 19.4% of S. mansoni miracidia and cercaria, respectively. The molluscicidal activity of 2,4-D was not influenced by the presence of Azolla [900 plants/liter] for 7 days, while Graminol effect was significantly reduced. However, the infectivity of S. mansoni miracidia to B. alexandrina snails was not affected by Azolla existence