Washington, August 30 : Scientists at the University of California, Davis have developed an odourless chemical that can lure gravid female mosquitoes, and help play a key role in surveillance and control programs for Culex species that transmit diseases like West Nile virus, encephalitis and lymphatic filariasis.
Lead researcher Walter Leal, a chemical ecologist, has revealed that the synthetic mixture, containing compounds trimethylamine and nonanal in low doses, is just as enticing to Culex mosquitoes as the current attractants, but this one is odorless to humans.
The chemical- and water-infused gravid female traps draw blood-fed mosquitoes ready to lay their eggs, but their smell is highly offensive to those monitoring the traps and to people living near them.
The UC Davis researchers say that the urge to address this problem drove them to find more user-friendly approach.
The researchers have revealed that an extensive field research in Recife, Brazil, a region known for its high populations of Culex quiquefasciatus, has shown that a combination of trimethylamine and nonanal "is equivalent to the currently used infusion-based lure, and superior in that the offensive smell of infusions was eliminated."
"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," Leal said.
The researcher further says that another advantage of the gravid traps is that with the capture of one female mosquito, that eliminates not only her, but hundreds of her would-be offspring.
"Each female mosquito has the potential to produce about 200 eggs, and she can have as many as five cycles. So when we capture a gravid mosquito, that can remove as many as 500 females," Leal said.
Since the compounds used in the research are "simple and inexpensive", the researcher say that their approach may be of great benefit to "third-world countries where Culex quinquefasciatus is a problem".