Kochi:Climate change hits Silent Valley dragonflies

Kochi: Climate change has hit the Silent Valley National Park leading to a sharp fall in the population of dragonflies such as 'global wanderer.'

This has been found in an annual survey held in the park located in the core of Nilgiri biosphere reserve.

Experts opined that this could be due to the aberrant rain pattern and successive floods that affected the state as the predaceous insects spend most of their lifetime as eggs and larvae under water.

The second edition of the Odonate (dragonflies, damselflies) survey was held jointly by the volunteers of the Society for Odonate Studies and the staff of the park from September 19 to 21.

"The first survey held last year in 11 camps across buffer and core areas of the park came up with 75 species of dragonflies and damselflies. The present survey takes the number of Odonate species to 91," said Samuel Vanlalngheta Pachuau, the wildlife warden, of Silent Valley National Park.

Though there was an increase in different species found in the region, a decrease in the number is evident in each of them.

"One disturbing finding is the fall in the abundance of dragonflies - a meagre average two sightings compared to 60 last year. The insects spend most of their lifespan in water bodies. The larvae could have been destroyed in floods which affected the region in the last two years.

More such surveys in different parts of the state will give a clear picture," said V. Balachandran, co-ordinator, Society for Odonate Studies.

Dragonflies and damselflies are seen as biological indicators that can provide crucial information regarding the health of aquatic habitats and climatic variations. Apart from this, the creatures are pest controllers that play a big role in controlling mosquito population.

Meanwhile, eight new species were discovered from the park. These include hemicordulia asiatica, which was previously reported from Periyar Tiger Reserve in 2017.

The rare dragonfly went unreported for over 80 years and the present sighting is only the second from any protected forest in the state.  

Macrogomphus wynadiccus(Wayanad bowtail ), onychogomphus nilgiriensis(Nilgiri clawtail), epithemis mariae (rubytailed hawklet), palpopleura sexmaculata(bluetailed yellow skimmer) and neurothemis intermedia(paddyfield parasol) were the other finds among dragonflies. Agrocnemis splendidissima(splendid dartlet), lestes dorothea(scalloped spreadwing), onychargia atrocyana(blackmarsh dart), phylloneura westermani(myristica bambootail), euphea disper(Nilgiri torrent dart) and protostica gravelyi(pied reedtail) were newly-sighted among the damselflies.