On the diversity and abundance of riparian odonate fauna (Insecta) of the midstream Chalakkudy River, Kerala, India

Abstract

The riparian Odonate insect diversity of the midstream Chalakudy River at six locations assessed from February 2018 to January 2019 has revealed the occurrence of 25 species of odonates. Among them,10 species are dragonflies belonging to seven genera of the family Libellulidae and the remaining 15 species are damselflies belonging to six families and 11 genera. Five endemic damselfly species have been recorded. Pseudagrion indicum is endemic to the Western Ghats, while the remaining four species, Vestalis apicalis, Libellago indica, Dysphaea ethela, and Heliocypha bisignata, are endemic to India. Diversity indices of the odonates in all the six locations were analyzed and it showed less abundance at sites where tourist activities are more and with thin native riparian vegetation. Further, the study has unequivocally revealed that thick native riparian vegetation is essential for their perching and existence. By and large, the uncontrolled tourism activities and habitat alteration interfere with the density and diversity of these endemic species.