Mosquitoes are not just annoying, they can also carry dangerous infections. Now, researchers believe they have discovered how the irksome insects identify their prey.
Malaria, yellow fever, dengue, West Nile virus, and many other dangerous illnesses are spread around the globe by mosquitoes, which are able to infect victims with little notice. However, relatively little was known about how the insects identified and selected a given host. Biologists questioned how various senses worked together to select a target for the flying insects.
University of Washington and the California Institute of Technology researchers examined mosquitoes in a wind tunnel, where the insects could be examined under controlled conditions. The chamber in which the insects resided was largely featureless, apart from a single black dot. Carbon dioxide, a gas which makes up a large portion of what we put out with each breath, was introduced into the chamber, exciting the insects to race toward the only visual stimulus - the dot.
"When we gave them the odor stimulus, all of the sudden they were attracted to this black dot. It's almost like the carbon dioxide gas turned on the visual stimulus for the mosquitoes to go to this black dot." Jeff Riffell of the University of Washington said.
Female mosquitoes require blood to feed their young. These creatures were found use a variety of senses to locate a viable, as well as unsuspecting donor. Using an acute sense of smell, the insects are able to identify when a warm-blooded potential donor is near. If this theory is correct, than mosquitoes may not select a chosen target until the creature is detected by its smell. Only later would secondary senses such as vision go into effect, honing in on the intended victim. When researchers followed the burst of carbon dioxide with water vapor or heat, the insects became even more focused on the target.
"Our experiments suggest that female mosquitoes do this in a rather elegant way when searching for food. They only pay attention to visual features after they detect an odor that indicates the presence of a host nearby. This helps ensure that they don't waste their time investigating false targets like rocks and vegetation," said Michael Dickinson of Caltech.
Health officials continually work on new means to deter or kill mosquitoes in areas where they could pose a significant hazard to human populations. This new research suggests troublesome insects could be dissuaded from homing in on humans or pets by disrupting their multisensory targeting technique.
Future investigations will examine how the insects respond to differing smells, including those that could repel the creatures.
Study of how mosquitoes identify and target animals was profiled in the journal Current Biology.
Photo: Sinu Kumar | Flickr
