Richness and diversity of odonates of the agricultural college and research institute, Vazhavachanur, Tamilnadu, India

Abstract

Investigations on the diversity of Odonata in and around the Agricultural College and Research Institute, Vazhavachanur, Tamil Nadu, India were studied. Eight locations were selected, of which sixteen Odonata species were recorded. In total, eleven dragonfly and five damselfly species were identified from Thiruvannamalai district, Tamil Nadu, India. Pantala flavescens, Diplacodes trivialis, Brachythemis contaminata and Ischnura aurora were recorded from all eight locations. Trithemis pallidinervis and Agriocnemis pygmaea were recorded from seven locations except from the farm pond and the open stretch area. Rhyothemis variegata was recorded only at the open stretch area. The results clearly show that, Odonates have specific habitat preferences for their growth and development. Four families Libellulidae, Gomphidae, Aeshnidae and Coenagrionidae were observed and collected during the study. Libellulidae were the most abundant family (56.25%) and comprised of 9 species, followed by Coenagrionidae (31.25%) with 5 species. Low species abundance was recorded within the Gomphidae and Aeshnidae families with 6.25% each. Simpson and Shannon Index showed maximum diversity in the open stretch area (0.8743 and 2.186, respectively) and minimum in location 8 (crop production area) and location 4 (Sathakuppam), respectively. Open stretch area showed maximum Richness Index (Margalef) (2.275) followed by farm pond (2.196) where recorded minimum in sathakuppam (1.276) location. Equitability J index, maximum species evenness (0.788) was recorded Location 6 i.e. farm pond (0.6727) followed by open stretch area 0.686.

Keywords

• Vazhavachanur
• Dragonfly
• Damselfy
• Libellulidae and Coenagrionidae