Aquatic Insects of Adhikhola River System in Waling Syangja

Abstract

Insects which spend fully or partially part of their life in water is known as aquatic insect. Aquatic insects are important part of aquatic ecosystem which play vital role in ecosystem functioning. Major Orders representing aquatic insects are Ephemeroptera, Plecoptera, Tricoptera, Odonata, Megaloptera, Diptera, Coleoptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera and Collembola. This study was conducted in Adhikhola River System, Waling, Syangja. Adhikhola River System in Waling consists of 4 River Mirdi Khola, Armadi Khola, Madi Khola and Adhikhola River of which Mirdi Khola, Armadi Khola, Madi Khola are tributaries of Adhikhola River. Twelve sampling site has been ascertained, three sites on each stream on the basis of different habitat (Forest, Agriculture and Urban). Each site was further divided into 3 point on the basis of heterogeneity. Insect collection was done by “Sweeping” method for littorial zone, “1minute kick method by D-Frame kick net for benthic zone, “Sieving” for sandy bottom of rivers and “All out search” was done for microhabitat. Sampling was done for two seasons Autumn and Winter. Identification was done by the use of standardized taxonomic key. A total 45 genera, 31 families and 8 orders were report from different sites of study area. Among 4 river stream Adhikhola River and Mirdi Khola were highly abundant followed by Armadi khola and Madi khola was least abundant. Abundance and Diversity of Insect was seen high in autumn than winter. Habitat wise diversity of Forest was highest followed by agriculture and Urban was lowest. But no significance difference was seen in between Seasonal Variation and Habitat Variation of Insect fauna. Insect Fauna showed significant negative correlation was seen with CO 2 and positive correlation with alkalinity in autumn. Since Diversity and abundance of insect were seen degrading in urban areas hence further research should be carried to know the precise condition of aquatic insect and river.