DAVIS, Calif., Oct 27, 2009 (UPI via COMTEX) -- U.S. scientists say they have
identified the dominant chemical naturally produced by humans that attracts some
mosquitoes to people.
University of California-Davis researchers said they discovered the odor
naturally produced in humans and birds that attract the blood-feeding Culex
mosquitoes, which transmit West Nile virus and other life-threatening diseases.
The scientists said their findings explains why mosquitoes shifted hosts from
birds to humans and paves the way for key developments in mosquito and disease
control.
Entomology Professor Walter Leal and postdoctoral researcher Zain Syed said they
found the semiochemical, nonanal, triggers the mosquitoes' keen sense of smell,
directing them toward a blood meal.
A semiochemical, the researchers explained, is a chemical substance or mixture
that carries a message.
"Nonanal is how they find us," Leal said. "The antennae of the Culex
quinquefasciatus are highly developed to detect even extremely low
concentrations of nonanal."
Birds, the main hosts of mosquitoes, serve as the reservoir for the West Nile
virus, Leal said. When infected mosquitoes take a blood meal, they transmit the
virus to their hosts, which include birds, humans, horses, dogs, cats, bats,
chipmunks, skunks, squirrels and domestic rabbits.
The research appears in the early online edition of the Proceedings of the
National Academy of Sciences.
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Copyright 2009 by United Press International