author(s)
Moni Kankana Kalita and Dipali Devi

abstract
In present study immunotoxic effect of organophosphate pesticide, chlorpyrifos formulation (Pyrifos-20 EC) on Philosamia ricini (eri silkworm) was evaluated. Herein, two sub lethal concentrations of chlorpyrifos (1.5 mg/L and 2.0 mg/L) were administered to eri silkworm and the effect on Phenoloxidase (PO), lysozyme enzyme activity and hemocyte immunity were investigated at 24-96 h time interval. Results showed at 72-96 h 2.0 mg/L concentration showed significant inhibition in enzyme activity. Likewise, after 24 h of exposure a significant increase in lysozyme activity was recorded in both pesticide exposed groups, however at 72-96 h significant decrease in lysozyme activity was measured. Moreover, after 48-96 h significant reduction in hemocyte abundance was observed (p<0.05). Changes in proportional counts of hemocytes showed that sub lethal chlorpyrifos exposure caused an increase of granulocytes and plasmatocytes in a concentration-dependant manner. However, prohematocytes, spehrulocytes and oenocytes abundance was decreased significantly (p<0.05) in chlorpyrifos exposed groups.