Vol. 3, Issue 1 (2018)
Species richness, diversity and conservation threats of Odonates in Dyamannana Lake (Kere), Bhadravathi Taluk, Shivamogga District, Karnataka, India
Author(s): MN Harisha, BB Hosetti
Abstract: The study was conducted to find out the status, diversity and conservation threats of Odonata at Dyamannana Lake, Shivamogga Disrtict during October 2015 to September 2016. Sampling was done by direct counts method and collected data were statistically analyzed to work out the magnitude of Odonate diversity. A total of 470 individuals of odonates belonging to 41 species in 29 genera under 6 families were recorded. The order- Anisoptera was found to be the most dominant with 76% (n=31) species, belonging to 3 families, followed by order- Zygoptera with 24% (n=10) species, under 3 families respectively. Among the order- Anisoptera, the family wise, abundance, richness, diversity and evenness indices was found to be maximum in Libellulidae (340, 4.1, 2.9, 0.72) followed by the Aeshnidae (38, 0.8, 1.3, 0.93) and minimum in Gomphidae (26, 0.3, 0.7, 1.0) respectively (Table 2). Similarly, among the order: Zygoptera, it was found to be maximum in Coenagrionidae (42, 1.6, 1.9, 0.92) and minimum in Platycnemididae (12, 0.5, 0.6, 0.94), however, it was least in Lestidae (12, but showed no significant indices value with only single species) respectively. The study revealed that, odonates and their habitats were under threat due to intensive anthropogenic activities, which are attributed to encroachment and loss of habitat. Also, addition of fertilizers and insecticides from the surrounding arecanut plantation lead to pollution and eutrophication of the lake, which not only affect the assemblage of Odonata population but also cause local extinctions.