ABSTRACT

Freshwater insects play important role in ecosystem functioning viz. nutrient cycling, primary production, decomposition and materials translocation. This study deals with diversity and distribution of aquatic insects from nine stations in the Aghanashini River of South-west India. The aquatic insects were sampled systematically and randomly in station-wise habitats, using standard protocols.  Genera level diversity varied from station to station. Ephemeropteran (Mayflies) and Coleopterans (beetles) indicative of good water quality were most diverse. Different functional feeding groups such as shredders, scrapers, collector-gatherers and predators have important roles in stream nutrient cycling. Functional feeding groups dominated with scrapers followed by collectors, predators and shredders respectively. Presence of pollution intolerant genera like Petersulla, Isonychia, Isca, Clypeocaenis, Helicopsyche etc. highlights the good quality of river water. The abundance of organic pollution tolerant Baetis and Hydropsyche in some downstream stations, nearer to human settlements, is a disconcerting factor. Probably members collected of genera Isonychia and Platybaetis from tributary streams are likely to be new species, as these genera hitherto were not assigned to any species in India. Routine biomonitoring of hill streams and rivers using aquatic insect indicators will facilitate better conservation of environment.

Keywords: Aquatic insects, diversity, mayflies, bio-indicator and Functional feeding group