Scientists Discover How Mosquitoes Can 'Sniff Out' Humans

An anonymous reader quotes a report from The Guardian: [R]esearchers say they have found the mechanism behind the insect's ability to home in on humans. Humans give off a fragrant cocktail of body odor, heat and carbon dioxide, which varies from person to person and mosquitoes use to locate their next meal. While most animals have a specific set of neurons that detect each type of odor, mosquitoes can pick up on smells via several different pathways, suggests the study, which is published in the science journal Cell. "We found that there's a real difference in the way mosquitoes encode the odors that they encounter compared to what we've learned from other animals," said Meg Younger, an assistant professor of biology at Boston University and one of the lead authors of the study. Researchers at the Rockefeller University, in New York, were baffled when mosquitoes were somehow still able to find people to bite after having an entire family of human odor-sensing proteins removed from their genome. The team then examined odor receptors in the antennae of mosquitoes, which bind to chemicals floating around in the environment and signal to the brain via neurons. "We assumed that mosquitoes would follow the central dogma of olfaction, which is that only one type of receptor is expressed in each neuron," said Younger. "Instead, what we've seen is that different receptors can respond to different odors in the same neuron." This means losing one or more receptors does not affect the ability of mosquitoes to pick up on human smells. This backup system could have evolved as a survival mechanism, the researchers say. "The mosquito Aedes aegypti is specialized to bite humans, and it is believed that they evolved to do that because humans are always close to fresh water and mosquitoes lay their eggs in fresh water. We are basically the perfect meal, so the drive to find humans is extremely strong," said Younger.

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