Posted by: Andrew Haynes30 JUN 2014
For many years we have tried to avert the attention of mosquitoes and other icky insects by smothering ourselves in substances that these pesky little critters find repellent. By smearing our skin with gunk that smells unpleasant to flying insects, we hope that they will buzz off elsewhere and pester someone else.
The main chemical on which we rely is deet (N,N-diethyl-meta-toluamide), a colourless oily liquid developed by the United States Army following its experience of jungle warfare during the 1939–45 war. (The name “deet” first appeared in the early 1960s, probably derived from the initials of “diethyl” and “toluamide”. I have no idea why it is commonly capitalised as “Deet” or “DEET”.)
But deet has its limitations. It can be irritant and may rarely cause severe skin reactions. And a US study involving employees of the Everglades National Park has found that insomnia, mood disturbances and impaired cognitive function are more common in those with extensive deet exposure than in those who are less exposed. There is even some evidence that deet may cause epileptic fits. On top of all this, mosquitoes are developing resistance to it.
A different approach to warding off mozzies has been taken by researchers at the US Department of Agriculture. Instead of trying to develop new chemicals that repel insects, they are investigating substances that disrupt the insects’ ability to sniff us out in the first place.
The group has isolated several compounds that occur naturally on human skin in trace quantities and appear to inhibit the mosquito’s capacity to smell and locate human victims. The most promising of these chemicals is 1-methylpiperazine, which is synthesised by skin bacteria. If this substance can be produced synthetically on a large scale, then wearing it could effectively render us invisible to mosquitoes.