Mosquito menace related to frogs disappearing?

New Today , Sunday, October 02, 2016
Correspondent : Nivedhika Krishnan
Chennai: Day in and day out we are bombarded with the latest technology to control the mosquito menace. While one company talks of a spray to kill mosquitoes, another advertises a repellant, while yet another says you just need to light a bit of paper to drive away the devilish mosquitoes. All this proves that we have come a long way from a natural protector - the frog - that was known to guzzle insects, especially mosquitoes.

Gone are the days when every rainy season was accompanied by the music of frogs' croaks. The amphibian, which played an important role in the food chain, has shrunk in population with the disruption of its natural habitats.

According to environmentalists, in a way, development of Chennai has hit the biodiversity chain here, exposing us to mosquitoes and insects.

The population trend (frog) is decreasing in reserve forests, national parks and wildlife sanctuaries (number of species 410 in Western Ghats which has the highest species of diversity with good population), informs Associate Professor and Head, PG &Research Department of Zoology, Pachaiyappa's College, N Shettu.

He says, "Frogs play an important role in the food chain as they maintain prey-predator (and it is the prey for snakes and birds) relationship. It feeds upon small insects and pests in the forest ecosystem."

But the present trend has triggered an equilibrium imbalance in the prey-predator relationship. He says, "The absence of frogs in the food chain may lead to increase in the population of insects, indirectly disturbing the ecosystem. A decrease in predators population leads to breakdown in the food chain."

"Their natural habitats are fresh water and marshlands. The city doesn't have either of these. Our stormwater drains are filled with filth and garbage. Similarly, we have erected buildings on marshlands. We disrupted the food chain a long time ago and it's impossible to think of controlling the mosquito menace with the help of frogs," says Pammal Green Exnora president MangalamBalasubramanian.

Concurring with her, Shettu says, "There are many factors influencing the disappearance of a species, which include housing and urban areas, mining and quarrying in forest areas, infrastructure development, natural ecosystem modifications, invasive and other problematic species, genes and diseases, pollution, geological events, climate change and severe weather."

Brushing aside the possibility of controlling mosquito menace with the help of frogs, he says, "We can control mosquitoes with the help of frogs but it solely depends upon the PVA (population viability analysis) of the frog and mosquito. The main disadvantage is that both the species in their grazing period occupy different niches - the frogs in floor of ecosystem and the adult mosquitos in the arboreal niche and the chance of interaction is comparatively less. Even though fish are used to control mosquito eggs, larvae and pupa in the aquatic medium, the frog being an amphibian - found both in water and land - it is possible only to some extent."

"If conservation efforts are strictly implemented, it may take a decade to regenerate frogs," Shettu speculates.

IN NUMBER

According to the Zoological Survey of India in 2014, more than 20 per cent of frogs and toads - 78 of the 340 species - found in India are under threat.

 
SOURCE : http://newstodaynet.com/chennai/mosquito-menace-related-frogs-disappearing
 


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