Effects of an organophosphorus insecticide, trichlorfon, on hematological parameters of the giant freshwater prawn, Macrobrachium rosenbergii (de Man)

Hemolymph osmolality, ion concentration, acid-base balance, and immune parameters in Macrobrachium rosenbergii (15-20 g) were measured after 8 days of exposure to 0-0.3 mg l−1 trichlorfon. A significant depression in hemolymph osmolality and Cl−1 contents were observed with exposure to 0.3 mg l−1 trichlorfon. Similarly, hemolymph pH, HCO3−, and TCO2 decreased significantly when prawns were exposed to concentration of greater than 0.2, 0.1, and 0.1 mg l−1 trichlorfon, respectively. A notable increase in the hemolymph pCO2 was observed with 0.3 mg l−1 trichlorfon. However, no significant differences in hemolymph oxyhemocyanin or protein levels were observed among prawns with 0-0.3 mg l−1 trichlorfon. These findings may have resulted from histological changes in the respiratory epithelium and/or the inhibitory action of the nervous system of respiration. Phenoloxidase activity in the hemocytes of prawns decreased significantly with exposure to greater than 0.2 mg l−1 trichlorfon. This indicates that trichlorfon reduces the immune ability of M. rosenbergii.