Dragon fly and Damselfly diversity in Thanal Agroecology Centre

By Administrator . on 14th May, 2019

Thanal agroecology centre, Panavally, is situated in Wayanad District located in the ecologically fragile Western Ghats.  A predominantly agrarian district -the name Wayanad stands for ‘vayal nadu’ (which means paddy lands in Malayalam). It also has a significant tribal population. The population – tribal and non-tribal-  mainly depend on cash crops and paddy  for their livelihood   and most of the land in the District is under cultivation. Panavally is a biodiversity rich area which is surrounded by the Kalindi river and the Brahmagiri hills. Thanal agro ecology centre is situated in an ecologically important area enriched by a river, forest and hills. Different species of birds, butterflies, dragonflies, fishes, snails, plants, trees etc are present in significant numbers.

The agroecology centre contains 200 varieties of traditional rice, 40 varieties of tubers, 80 varieties of non cultivated leafy vegetables, more than 40 varieties of forest trees, coffee, areca nut, coconut and pepper. Wild animals like elephants, deer, monkeys, bison, tigers etc are frequently seen at the centre.

120 species of birds, 35 species of dragonflies and damselflies, around 60 species of butterflies and 80 species of non cultivated leafy vegetables have been identified from the Thanal agro ecology centre.

Background:

I  began my work on biodiversity with documentation of non cultivated leafy vegetables in paddy fields and documented 20 species of non cultivated leafy vegetables. Most of these non cultivated leafy vegetables are considered as weeds and farmers destroy these valuable, medicinal, edible plants by using hazardous chemicals and herbicides. Discovering  the importance of each and every species in the paddy field got me interested  in further documentation of biodiversity in wetland ecosystem-paddy field. I could understand the value of paddy fields as a biodiversity area through this study. I realised that  the value of paddy fields lie not only in the value of rice produced  but also in  its biodiversity richness. So, I picked up documentation of dragonflies and damselflies (Order- Odonata), colourful insects of wetlands, which are great predators in paddy fields. The life history of odonates is closely associated with wetlands. Adults lay eggs in specific aquatic habitats.  Male odonates are generally more brightly coloured than females.

Objective and methodology:

Objective of this study was to analyse the diversity of dragonflies and damselflies present in the Thanal agro ecology centre, Panavally. Weekly observation and photo documentation of dragonflies and damselflies was done during the second crop paddy season (September- December, 2013 and 2014). Identification of the observed damselflies and dragonflies was done  with the help of an e book named Common Odonates of Central India written by Andrew, R.J., Subramaniam, K. A. & Tiple, A. D. (2008) and with the help of Mrs. Rajasree, a researcher in biodiversity.

Dragonflies:

20 species of dragonflies under three families were identified from the Thanal agro ecology centre. They are club tails (Family: Gomphidae), darner (Family: Aeshnidae) and skimmers (Family: Libellulidae). Among these most of the dragonflies identified were under skimmers (Family: Libellulidae). Skimmers are the most diverse group of odonates. Ditch jewel (Brachythemis contaminata), ruddy marsh skimmer (Crocothemis servilia), ground skimmer (Diplocodes trivialis), fulvous forest skimmer (Neurothemis fulvia), green marsh hawk (Orthetrum sabina), crimson-tailed marsh hawk (Orthetrum pruinosum) and wandering glider (Pantala flavescens) are the most common dragonflies found in the paddy fields observed. Among these thousands of wandering glider were found swarming over harvested fields and surrounding playgrounds during early morning and evening.

Some dragonflies like blue darner (Anax immaculifrons), crimson marsh glider (Trithemis aurora) and black stream glider (Trithemis festiva) were found along the banks of the river and usually found  perching among emergent water plants.

Damselflies: 15 species of damselflies under six families were identified. They are marsh darts (Family: Coenagrionidae), bush darts (Family: Platycnemididae), bambootails (Family: Protoneuridae), spreadwings (Family: Lestidae), glories (Family:Calopterygidae) and stream jewels (Family: Chlorocyphidae).Pigmy dartlet (Agriocnemis pygmaea), golden dartlet (Ischnura aurora) and yellow-striped blue dart (Pseudagrion indicum) were frequent visitors to the paddy fields. Saffron-faced blue dart (Pseudagrion rubriceps), stream glory (Neurobasis chinensis), stream ruby (Rhinocypha bisignata), river heliodor (Libellago lineata) were confined to hill streams and rivers.

Conclusion:

The paddy agroecosystem is an integrated water- dependent system, which includes many kinds of living organisms among which birds, fishes, reptiles, amphibia, arthropods and plants are prominent. Paddy fields play an important role as agricultural land (to produce rice and in some cases fishes and other crops like vegetables and legumes in non-paddy season), in addition it also provides a habitat for various animals and plants. Some species complete their life cycle in the paddy field. In the case of dragonflies and damselflies, they lay their eggs in paddy fields, and the larvae grow in paddy fields, the adults frequently visit paddy fields for predation as well. Dragonflies and damselflies are the best predators in paddy fields. If we use chemicals and pesticides in paddy field these insects  will not find their food, and through this we will destroy both biodiversity in paddy fields and also an effective means of biological pest control. When we adopt biodiversity based ecological farming, such mutually beneficial interaction of multiple species will exist. It will increase the ecological and economic value of the paddy fields.  Only a holistic approach towards these eco-systems can help sustain them so that our food security in the long term is also assured. Therefore, protecting such eco-systems is a necessity rather than a luxury