author(s)
Gouri Sankar Boruah, Susmita Gupta

abstract
An investigation was carried out to compare the insect diversity and ecosystem health of one man made and one natural pond of Cachar District, Assam. Physico-chemical properties of water in the two systems also have been studied. Dissolved oxygen in site 1 which is a man-made pond, was found very low and showed significant positive correlation with pH. Nitrate concentration of site 1 ranged from 0.26 mg/L to 0.54 mg/L and in site 2 (natural shallow water pond) it ranged from 0.14 mg/L to 0.50 mg/L. All total thirteen species were recorded from these two ponds, nine species from site 1 and twelve species from site 2. Five orders, nine families from site 1 and seven orders, twelve families from site 2 were recorded. Shannon H’ less than 1 for each site indicated disturbed condition of water of both the ponds. Shannon H’ showed very high significant positive correlation with transparency. Both the sites were found to be dominated by pollution tolerant species. Different biomonitoring scores like BMWP and SIGNAL also revealed stressed condition of these two water bodies. Ecology and anthropogenic impact on the water quality of both the ponds have been discussed in the paper.