USA: Researchers develop odourless mosquito trap

Researchers from the US University of California, Davis, have developed a commercially-valuable mosquito trap that - unlike the scents currently used to lure these insects to their doom - does not repel humans with its odour.

The new synthetic formula is cheap and easy to use. It contains low doses of trimethylamine and nonanal and appears to entice the bloodsuckers without the stench of other chemical and water infused traps, that sometimes include manure.

Described in the US Public Library of Science Journal, the discovery could play a key role in the surveillance and control programmes for the Culex mosquito species which transmit such diseases as West Nile virus, encephalitis and lymphatic filariasis.

Chemical ecologist and research team leader, Professor Walter Leal, a specialist in insect physiology, said what prompted his team to find a new attractant was simply that the traps he and researchers had to use to collect specimens were most unpleasant to use.
Mosquito populations are typically monitored with two traps: the conventional carbon dioxide traps and the gravid female trap that is a combination of chemicals and water.

But mosquitoes captured in the carbon dioxide traps are less likely to be infected with disease than those in the gravid traps.

"The gravid traps are more important for surveillance as they capture mosquitoes that have had a blood meal and thus, more opportunity to become infected," said Leal.

By monitoring gravid traps containing West Nile virus-infected mosquitoes, control authorities and health officials can best determine when it is time to spray. Using the new trap, these important assessments can be carried out without users or people living nearby having to deal with the unpleasant smells.

Leal said that another advantage of gravid traps over those killing males is that the capture of one female mosquito eliminates not only her but hundreds of her would-be disease-spreading offspring.

monica.dobie@uw-news.com