Kill 8217;em with plants

Every time we meddle with the ecosystem in an attempt to make our life comfortable, we only succeed in making the situation worse. For ex...

Every time we meddle with the ecosystem in an attempt to make our life comfortable, we only succeed in making the situation worse. For example, mosquitoes are getting tougher every year. Nowadays, one even sees them in the coldest months of winter. Each year, about 300 million clinical cases of malaria occur world-wide, and over one million people die.

All over the world, man has gone after mosquitoes with million of gallons of DDT and other insecticides. These chemicals were initially effective but have lost their punch; now we have insecticide-resistant mosquitoes. The mosquitoes8217; resistance to anti-malaria drugs presents a huge threat to treatment. So entomologists and bio-technologists are now using natural means to blunt the onslaught of mosquitoes. They are trying to understand the mosquito8217;s behavior and develop transgenic plants capable of producing a mosquito repellent odour. And they8217;ve found some interesting facts.

Mosquito species select their hosts on the basis of the odour which emanates from them.

Lactic acid and some other unidentified compounds isolated from human skin attract mosquitoes. The receptor site for L-lactic acid seems to be a sensory apparatus on a mosquito8217;s antennae. At puberty, many of our glands wake up and start releasing hormones which, in turn, stimulate oil glands in the skin. This oil or its decomposition by skin bacteria gives rise to a specific odour that attracts mosquitoes.

Carbon dioxide exhaled during respiration directs the mosquito to its prey.

Long-term stimuli that attract mosquitoes include movement of body parts and colour, especially dark colours.

Mosquito orientation for landing on skin is largely visual with contribution from local body heat and humidity.

Host selection by mosquitoes is also based on age and sex. Adults attract the bugs more than children and males are more prone to mosquito bites than females.

The size of the host bears a direct relationship to the number of mosquito bites.

So what would you call a huge man with an irresistible odour, huffing and puffing while jogging in dark-coloured shorts? A mosquito8217;s dream come true.Fortunately, there are eco-friendly ways to combat this menace. Plants that produce elements that repel mosquitoes include Neem, Tulsi and transgenic citrosa. Citrosa combines the genes of citronella with those of geranium. Citronella produces insect-repellent oil, but the oil remains in the plant. Geranium, on the other hand, is a cold climate ornamental plant that produces a pungent fragrance that spreads all around. A transgenic plant combines the positive features of both the plants 8212; it has the ability to secrete citronella oil that mosquitoes cannot withstand, and the scent spreads into the air for metres around.