POPULATION-DYNAMICS OF AQUATIC HEMIPTERANS IN THE RIVER COOUM, MADRAS

River Cooum, finding its course right across the Madras City, is well known for its polluted status. The first three stations constitute the upstream and rest six come under the downstream. Downstream is highly polluted as evidenced by the increase in BOD, COD, and free CO2. But the population of aquatic hemipterans was in an increasing order from the stations Thiruverkadu (1st station) to Nerkundraon (2nd station) a nd Koyembedu (3rd station). The abundance of hemipterans in station 3 is due to the rich source of nutrients alongwith abundant aquatic vege tation. Among the hemipterans found, the adult and nymphal population of D. indicus was highest followed by R. filiformis, R. elongata and A . bouvieri. During monsoon months there was an increase in the populat ion of aquatic hemipterans, whereas a decrease in summer months, indic ate that temperature and rainfall have considerable influence on the p opulation of aquatic hemipterans. The ecological difference between th e species of aquatic hemiptera appear to depend upon physical and biol ogical factors. Accordingly at present aquatic hemipterans in the upst ream of river cooum can be used as biological control agent for mosqui to control.