Chennai

Keeping mosquitoes at bay with a ‘firm hand’

A nochi tree in front of an apartment complex on Car street in Triplicane.

A nochi tree in front of an apartment complex on Car street in Triplicane.   | Photo Credit: S. R. Raghunathan

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Not long ago, there was a drive to promote ‘nochi’ as a natural mosquito repellent. The Corporation was a central player in it. Now, the small-sized tree seems to be plunged in the shadows

Botantists as well as laymen often resort to easy, everyday terms and images to explain the anatomy of plants and trees.

Here is a case in point: In the vitex negundo, every compound leaf with its leaflets is compared to a “hand with spread fingers”.

Botanists out there would exclaim, “Oh yeah, that is called digitate leaf, one that resembles a spread hand.”

In the case of vitex negundo, science and workaday life clearly meet.

Actually, there can’t be anything better than the imagery of a hand to describe a part of it, as this plant is said to keep mosquitoes at bay — if one may add for effect, with a firm hand.

The strong smell that leaves of vitex negundo exude, even when the leaves have dried up, are not to the liking of mosquitoes.

So, not long ago, there was a drive in Tamil Nadu to promote vitex negundo – called “nochi” in Tamil – as a natural mosquito repellent.

In 2013 and 2014, Chennai Corporation was promoting nochi trees in a huge way by giving away free saplings of the species to residents.

Karpagam Padmanaban, committee member of Indira Nagar Women's Association, says nochi plants were being promoted intensely.

Keeping mosquitoes at bay with a ‘firm hand’

“We received free saplings from the Corporation and we were giving them away to residents over a period of time. People sought nochi saplings avidly. At that time, I was the secretary of the association and was closely connected with the nochi distribution work. I remember that in one extremely busy day, we gave away around 2,000 saplings. Before it has grown into a tree, some people have it in pots and keep them inside the house during day-time to keep mosquitoes away.”

Vitex negundo is a small-sized tree, and with regular and careful pruning, it can be kept to a manageable height as a small bushy tree.

P.T. Sugantha, a resident of Car Street in Triplicane, believes in the ability of the dry nochi leaves to keep not only mosquitoes, but also rats at bay. There is a nochi tree right in front of the apartment unit she lives in.

“It was planted by the Corporation. Many residents of the locality pluck the leaves and make use of them as mosquito repellent and as an ingredient in steaming to treat cold.”

It may be noted that in a study, which is available at researchgate.net, three researchers — Rajendran Ramasamy, Radhai Rajan and Rajalakshmi Velmurugan — explored the potential of vitex negundo as a key element in the creation mosquito-repellent textile-fabrics. According to the study, the fabrics that were subject to a treatment involving “vitex negundo leaf extract” showed “mosquito repellent efficiency” for as long as “15 washes”. So, there is so much faith in the nochi leaves. Given that, it is surprising that nochi has not been in any drive lately. In fact, considering how much it was promoted only a few winters ago, it is baffling that it is not as abundantly found as expected in residential areas.

Nochi can be one weapon in the arsenal to check mosquitoes. Let us have our nets and other things that promise to protect us from mosquitoes. But, let us have a sprinkling of nochi trees too. By doing so, one would only be erring on the right side of caution. It will add to the greenery around the house, which is a great thing.

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Printable version | Dec 9, 2019 2:03:32 PM | https://www.thehindu.com/news/cities/chennai/keeping-mosquitoes-at-bay-with-a-firm-hand/article30059795.ece

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