Histopathological Effect of Paraquat (Gramoxone) on the Digestive Gland of Freshwater Snail Lymnaea luteola (Lamarck: 1799) (Mollusca: Gastropoda)

Abstract. Histopathological alterations induced by paraquat in the digestive gland of the freshwater snail Lymnaea luteola were investigated. Samples were collected from the Kondakarla lake (Visakhapatnam, Andhra Pradesh, India), where agricultural activities are widespread. Acute toxicity of series of concentration of paraquat to Lymnaea luteola was determined by recording snail mortality of 24, 48, 72 and 96 hrs exposures. The Lc50 value based on probit analysis was found to be 0.073 ml/L for 96 hrs of exposure to the herbicide. Results obtained shown that there were no mortality of snail either in control and those exposed to 0.0196 ml/L paraquat throughout the 96 hrs 100% mortality was recorded with 48hrs on exposed to 0.790 ppm concentration of stock solution of paraquat. At various concentrations paraquat causes significant dose dependent histopathological changes in the digestive gland of L.luteola. The histopathological examinations revealed the following changes: amebocytes infiltrations, the lumen of digestive gland tubule was shrunken; degeneration of cells, secretory cells became irregular, necrosis of cells and atrophy in the connective tissue of digestive gland.