Anew study reports that a mosquito's sense of smell is more complicated than we once thought. And it may explain why this annoying insect is so good at seeking you out at a barbecue or in your bedroom and biting you—as well as lead to new strategies to prevent the potentially deadly diseases transmitted by its bite.
Meg Younger, a neuroscientist at Boston University, is co-author of the study. She exhales(呼气)gently into one of the mosquito-filled cages. A waft of carbon dioxide blows across the insects, and they go wild. "And now, they're looking fora target like the complex mixture of human body smell—a smell that's attractive to the mosquitoes," Younger explains.
In many parts of the world, this attraction isn't merely an annoyance for humans. It's a major health problem. Mosquitoes transmit diseases to humans. These diseases include dengue, Zika, chikungunya fever and malaria. The last disease alone causes over half a million deaths each year.
So scientists have attempted to break this attraction. But try as they might, the little mosquito has resisted. "They're really good at what they do," Younger says. Most of what we know about the neuroscience of smell comes from mice and fruit flies, where the wiring is fairly simple. Each neuron(神经元) in the nose has one kind of receptor(感受器) that detects a single kind of smell—say, a banana. And all the neurons with receptors for the banana smell connect to the same part of the brain. Younger and the others studied mosquito brains, where she found that each neuron has multiple receptors that can detect multiple smells.
This work could give researchers additional ways to battle the insects like developing traps that contain new smell mixtures that are more appealing than people.
"It's an enormous study," says Josefina del Marmol, a neurobiologist at the Harvard Medical School. She says there's more work to be done to check. neuron by neuron, that each one actually responds to all the smells it has receptors for. But regarding the central finding, she says, "It really does change a lot about what we know of how insects perceive the world."
