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No fishy tail: Declining frog, fish populations cause for rise in dengue, say environmentalists

Sunday, 18 November 2012 - 3:05pm IST | Place: New Delhi | Agency: PTI
Naturalist Raza H Tehsin said there is an urgent need to introduce and increase the population of weed fish in water bodies and wetlands and also curb the illegal export of frog legs.

Ever thought that the dwindling count of frogs in water bodies can be a cause of the manifold increase in mosquito population and subsequent rise in vector-borne diseases? Yes, say environmentalists.

The demise of filmmaker Yash Chopra due to dengue came as a rude shock to the country. Also in the national capital, a new variety of dengue-causing mosquito — Asian Tiger — has been spotted which is believed to be resistant to traditional forms of control mechanisms.

According to municipal officials, aedes albopictus or Asian tiger mosquito breeds in the open as against yellow fever-causing aedes aegypti mosquito, which also causes dengue and breeds inside homes.

Environmentalists attribute the reasons for the increase in vector-borne diseases to ecological imbalance and global warming besides increasing human population and their food habits.

Naturalist Raza H Tehsin said there is an urgent need to introduce and increase the population of weed fish in water bodies and wetlands and also curb the illegal export of frog legs.

"Frogs are almost wiped out from our subcontinent. Frogs are the major predators of mosquito larvae. In every wetland — flowing or stagnant — there was abundance of frogs, surviving largely on mosquito eggs and larvae," Udaipur-based Raza told the Press Trust of India.

He said that while frogs from water bodies have dwindled, mosquito population has increased manifold.

According to Raza's daughter and Udaipur's wildlife warden Arefa, decline in the population of small fish is also responsible for the population of mosquitoes going up.

"In almost all the water bodies and wetlands of India there were numerous small fish. The number of weed fish species found in different water bodies has not yet been surveyed and ascertained," she said.

Besides, many exotic fish are introduced in water bodies for commercial purposes. "There is no study to see how this affects the ecosystem of our water bodies. Some of the introduced fish are voracious carnivores, like tilapia and magoor, which feed on small fish."

She said many small species of fish, which are not only predators for vector larvae but also a very important link in the food chain, have depleted. "The fingerlings of these carnivore weed fish too are predators of larvae. With their dwindling numbers malaria, dengue, chikungunya and other vector-borne diseases are increasing all over India," Arefa said.

Interestingly, an international team of scientists, educators, policymakers and naturalists dedicated to protecting the world's amphibian species have started a campaign called 'Save the Frogs'. On April 28, the group organised the fourth annual 'Save The Frogs Day'. In India, the main event was organised in Guwahati in Assam.

In Delhi, over 1,200 cases of dengue have been reported so far. Two children have died of the disease since it began spreading early last month.

In 2011, a total of 857 cases were reported in Delhi and five deaths took place while in 2010, a total of 5,682 dengue cases were reported and eight people died.

Meanwhile, the Delhi government has decided to launch an SMS campaign to educate people about preventive measures to contain the spread of dengue.


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