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Natural born repellents

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31.03.2004

Are you a mosquito magnet? If you are, it’s not your sweet smelling blood that attracts them, scientists say – you simply lack a chemical that some humans produce that masks your attractiveness to bugs, tricking them into thinking that you are not a suitable host. “For the first time, we can identify exactly which chemicals the insects respond to”, says James Logan, who will be presenting his work at the annual SEB meeting in Edinburgh (29th March – 2nd April 2004, session A6.9). James Logan (Rothamsted Research) and Dr. Nicola Seal (University of Aberdeen) will discuss how identifying the chemicals that make some humans unattractive to biting insects will soon lead to the development of natural insect repellents.

It seems that only some humans produce these host-masking chemicals. To identify them, human volunteers are wrapped up in foil bags. Air is pumped through the bags and collected through traps at the other end, resulting in bottles of human scent. Using a new technique, the antenna of female mosquitoes are strapped to a computer and presented with the volatile chemicals collected from human skin. The computer displays a trace for the chemical and a trace for the insect response.

Dr. Seal studies the behaviour of the Scottish biting midge and the farmyard midge. She presents midges with a choice between human derived chemicals in a wind tunnel to identify which compounds the midges find most and least attractive.

Using natural human ‘masking’ compounds the researchers hope to develop a safe, natural, odourless insect repellent in the near future. It is hoped that the new materials will be more effective than DEET as they relate to natural host selection rather than products of chemical screening.

Yfke van Bergen | Source: alphagalileo
Further information: www.sebiology.org/Meetings/pageview.asp?S=2&mid=21

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