Diversity of Odonata in the rice fields of Tamil Nadu

Odonata is one of the most predominant natural enemy of the rice ecosystems and their diversity in rice fields from different parts of Tamil Nadu viz., Coimbatore, Aduthurai, Pudukkottai, Ramanathapuram, Bhavanisagar and Gudalur was studied. The Odonata assemblage comprised 21 species under 19 genera under 4 families. Anisoptera (dragonflies) were dominant with 15 species and 14 genera over Zygoptera (damselflies) (6 species, 5 genera). Libellulidae (Anisoptera) was the most speciose family with 14 species followed by Coenagrionidae (Zygoptera) with 5 species. Diversity analysis of Odonata from rice fields of Tamil Nadu revealed that the order of Simpson Diversity index (SID) of diversity was Coimbatore (0.89) > Bhavanisagar (0.88) > Aduthurai (0.87) > Ramanathapuram (0.87) > Gudalur (0.84) > Pudukottai (0.82). Margalef index (α) of species richness were high in Coimbatore (2.33) and least in Gudalur (1.55). Eveness of species within the region (Pielou`s evenness index, E1) was the highest for Bhavanisagar (0.94) and the lowest for Aduthurai (0.84). Among the different regions, Odonata in rice fields of the Coimbatore and Aduthurai were found to have a maximum similarity.