The Effect of Paraquat (Herbicide) on the Mantle of Freshwater Snail Lymnaea luteola (Lamarck:1799)

Abstract

Mantle cavity act as a respiratory organ in most molluscs and is the specialized organ of the gastropods for it not only bears the glands that secrete the shell but also acts as buffer between the hard calcareous shell and the animal itself, spreading like a cushion through the entire inner surface of the body whorl. It is highly muscular, thin and bound by a single layer of epithelial cells. The present study was designed to investigate the histopathological effect of paraquat on the mantle of freshwater snail L.luteola. Acute toxicity of concentration of paraquat to L.luteola was determined by recording the snail mortality of 24,28,72 and 96 hrs exposures. The LC ₅₀ value based on probit analysis was found to be 0.073 ml/L for 96 hrs of exposure to the herbicide. Microscopical examination of treated animals revealed severe structural alterations in the mantle of L.luteola. The glandular cells exhibited a mild to heavy bioaccumulation of the herbicide which was a time dependent effect. At various concentrations paraquat causes significant dose dependent changes such as : desquamation of epithelial cell, atrophy of muscle fibers, necrosis, in respect of glandular cells.