Functional Feeding Groups among Aquatic insects of the East Kolkata Wetlands
By: Paulami Maiti, Durba Bhattacharya
Key Words: Wetlands, Sewage fed, Insects, Functional feeding groups, Predators.
J. Bio. Env. Sci. 8(5), 116-127, May 2016.
Habitat complexity of wetlands supports diverse organisms where aquatic insects control the structure and dynamics of the food web. In the present study, biodiversity features of aquatic insects are dealt with reference to their taxonomic and functional diversity. Sampled specimen were assigned a habitat and ‘functional feeding group’ as proposed by Cummins and Klug (1979) . Insect specimen were collected in the sewage fed ponds of the East Kolkata Wetlands, where about 17 species of coleoptera , 25 species of hemiptera, 3 genus of odonates, 1 aperygota; besides juveniles of ephemeroptera, lepidoptera, zygopteraand dipteral were recorded. These were assigned‘ Functional Feeding Groups’, based on their feeding mode, type of food, morpho-behavioral mechanisms of food acquisition and the size of the food particle.It was observed that the community was dominated by predators(38 species) while collectors/gatherers represented only by the Collembola,Ephemeroptera, members of the family Corixidae (hemiptera )and dipteran larva. Most of the coleopterans,hemipterans and odonate larva were predators with only the members of family Hydrophilidae(coleopterans) were scavengers. Shredders were presented by the lepidopteran larva only. Aquatic insects are considered as generalist predators. High ratio of predators as compared to the other groups is indicative of top down control where slow turnover of predatory taxa is dependent on fast turnover of prey species. Predatory fish often exhibit top-down control in water bodies with low macrophytic growth. However, in these wetlands with dense macrophytes and with predominance of non predatory carps,predation by fish is almost absent. As a result predatory insects control the abundance and diversity of other organisms.