Use of Aquatic Insects as Biomonitoring Tools to Assess the Water Quality Status of Two Freshwater Lakes of Mysore, Karnataka, India

The present study encompasses the use of aquatic insects as bio-indicators for monitoring the health of two freshwater lakes- Varuna Lake and Dalvoy Lake in Mysore district, Karnataka, India. Monthly sampling from six sampling sites in both lakes was conducted for a period of six months (April 2019–September 2019) between 7:00 a.m. - 10:00 a.m. local time. A total of 34 species of aquatic insects were recorded, 28 species from Varuna Lake and 22 species from Dalvoy Lake. The insect orders Coleoptera and Hemiptera accounted for the highest number of species from both lakes. The diversity indices such as the Shannon index (2.86), Evenness (0.62), and Margalef’s index (4.64) were higher in Varuna Lake as compared to Dalvoy Lake. Family-level biotic indices and scores further revealed that Varuna Lake was the least polluted and had higher species richness than Dalvoy Lake. Physicochemical factors like electrical conductivity, total dissolved solids, calcium, and hardness were elevated in Dalvoy Lake, suggesting perturbation of the water. The results of our study suggest that biotic indices, in conjunction with physicochemical studies, are useful for determining the overall health status of a particular water body.