Washington: A new study, conducted by researchers at Cornell and Binghamton University now finds that mosquitoes can hear over distances much greater than anyone suspected.
Their findings were published in the journal Current Biology.
Scientists earlier believed that organisms require eardrums for long-range hearing, and that the feathery antennae with fine hairs that mosquitoes and some insects use to hear only worked at close distances of several centimetres (a few inches).
However, a series of experiments has now provided neurophysiological and behavioural evidence that the Aedes aegypti mosquitoes – which transmit such diseases as yellow fever, Dengue, Zika, West Nile and Chikungunya viruses – can hear specific frequencies as far away as 10 meters (32 feet) or more.
These frequencies overlapped well with the frequencies of female mosquitoes in flight as well as human speech.
Speaking about the development, senior author Ron Hoy, said, “It’s been known for quite a long time that male mosquitoes are drawn to the sound of the female’s beating wings.
Hoy noted that since mosquitoes mate in mid-air, the sound of the female’s wings buzzing sets the males in motion. Menda fitted mosquitoes with an electrode in their brains and made neurophysiological recordings of the auditory nerve being stimulated by pure-tones emitted from a loudspeaker 10 meters away.
Researchers found that the sweet spot of frequency that the mosquitoes are sensitive to was between 150 to 500 hertz.
The mosquitoes’ frequency range for hearing also overlapped with human speech. “The most energetic frequencies of an average human vowel are in the range of 150 to 900 hertz,” Hoy said, so “they should be able to hear” people speaking.
While the study offers both neurophysiological and behavioral evidence that male mosquitoes hear sounds from far field, it offers no proof that they use it to home in on people.
The insects are known to pick up sensory cues such as carbon dioxide, odors and warmth to locate people. But the results do show an intriguing correlation, Hoy said.