TOXIC EFFECTS OF LEAD ON THE BIOCHEMICAL PARAMETERS OF THE HYACINTH WEEVILS NEOCHETINA-EICHHORNAE THROUGH THE TROPHIC LEVELS OF FOOD-CHAIN

Lead accumulation as determined by Atomic Absorbtion Spectroscopy was found to be higher in the roots than in the aerial parts of the aquati c plant Eichhornia crassipes Mart (Solms). However, Pb accumulation in the leaves of the Eichhornia plants had more significant effects with respect to ecotoxicological studies. The hyacinth weevils Neochetina eichhornae feeding on lead treated plants bioaccumulated about 5-10% o f Pb through the trophic levels of food chain. Studies on the biochemi cal, changes in these insects revealed a drastic decline in the protei n content with an increase in the free amino acid pool. The higher act ivity of alanine and aspartate aminotransferases implied their role in metal stress conditions. This study demonstrated the biotransfer of a toxic metal Pb from the aquatic environment to the insects via the tr ophic levels of food chain - a unique model system for ecotoxicologica l studies.