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

ABSTRACT

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