Aquatic insects of a tropical rain forest stream in Western Ghats, India

Abstract

In the studies on diversity, abundance and distribution of aquatic insects in Kallar stream and its tributaries in Western Ghats, collected on a monthly basis from five different sites revealed a total of 13,510 individuals belonging to 9 orders, 61 families and 125 genera. Trichoptera was the most dominant order with maximum number of individuals. It was followed by Ephemeroptera, Odonata, Hemiptera, Plecoptera, Coleoptera, Diptera, Megaloptera and Lepidoptera. Shannon-Weiner, Simpson dominance and Margalefs richness indices were found to be highest in site 5 and lowest in site 3. The most pollution sensitive aquatic insects are high in the main Kallar stream (site 5) compared to the tributaries. In the tributaries many anthropogenic activities are taking place and these factors have direct and indirect impact on the diversity of aquatic insects. So this may be the reason for the low abundance of the pollution sensitive taxa in the tributaries compared to the main Kallar stream.