No more big stink: scent lures mosquitoes, but humans can'...( DAVIS--Mosquito traps that reek like...)

DAVIS--Mosquito traps that reek like latrines may be no more.

A University of California, Davis research team led by chemical ecologist Walter Leal has discovered a low-cost, easy-to-prepare attractant that lures blood-fed mosquitoes without making humans hold their noses.

The synthetic mixture, containing compounds trimethylamine and nonanal in low doses, is just as enticing to Culex mosquitoes as the current attractants, Leal said, but this one is odorless to humans.

The research, published in the current edition of the Public Library of Science Journal or PLOS One, could play a key role in surveillance and control programs for Culex species, which transmit such diseases as West Nile virus, encephalitis and lymphatic filariasis.

Oviposition or gravid female traps draw blood-fed mosquitoes ready to lay their eggs, but the chemical- and water-infused traps just plain stink, Leal said. The smell is highly offensive to those monitoring the traps and to people living near them.

That prompted the UC Davis researchers to launch a multidisciplinary approach to find more user-friendly, chemically based lures for gravid Culex mosquitoes.

Their extensive field research in Recife, Brazil, a region known for its high populations of Culex quiquefasciatus, showed that a combination of trimethylamine and nonanal "is equivalent to the currently used infusion-based lure," Leal said, "and superior in that the offensive smell of infusions was eliminated."

The Leal lab searches for attractants in two ways. The first is the conventional chemical ecology approach or finding smells that attract mosquitoes. The second, or what Leal has coined "reverse chemical ecology," involves studying olfaction after identifying attractants.

Mosquito populations are typically monitored with two traps: the conventional carbon dioxide traps and the gravid female trap. Mosquitoes captured in the carbon dioxide trap
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