According to researchers at Cornell and Binghamton University, mosquitoes can hear far greater distances than anyone suspects.
Their findings have been published in the journal Current biology.
Until now, scientists believed that organisms required eardrums for long-range hearing and that the feathered antennae with fine hairs that mosquitoes and some insects used to hear would only work at close distances of a few centimeters (a few centimeters) .
A series of experiments has now provided neurophysiological and behavioral evidence that Aedes aegypti mosquitoes – which transmit diseases such as yellow fever, Dengue, Zika, West Nile and Chikungunya viruses – can hear specific frequencies up to 10 meters (32 feet) or more .
These frequencies superimposed well on the frequencies of female mosquitoes in flight and human language.
"It has long been known that male mosquitoes are attracted to the sound of the female's flying wings," said Ron Hoy, a professor of neurobiology and behavior at Cornell and senior author of the paper. Gil Menda, postdoctoral researcher in the Hoy laboratory, is the first author of the paper.
Hoy noticed that since the mosquitoes mate in mid-air, the sound of the wings of the female buzzer sets the males in motion. Menda mounted the mosquitoes with an electrode in the brain and made the neurophysiological recordings of the auditory nerve stimulated by pure tones emitted by a loudspeaker 10 meters away.
"They are listening at distances that normally require eardrums, but these are hairs," Hoy said. The eardrums work by sensing the pressure of the sound waves, while the thin hairs perceive the sound from the air particles that vibrate at certain frequencies.
Then they transferred the nerve physiology equipment into a super silent anechoic room run by collaborator Ron Miles, a mechanical engineering professor at Binghamton University. "It's the quietest room in the Northeast and maybe in the country," Hoy said.
"We found the weak point in the frequency at which mosquitoes are sensitive was between 150 and 500 hertz," said Menda.
The frequency range of hearing mosquitoes also overlaps with human language. "The most energetic frequencies of an average human vowel are between 150 and 900 hertz," Hoy said, so "they should be able to hear" the people talking.
While the study offers both neurophysiological and behavioral evidence that male mosquitoes hear sounds from afar, they offer no evidence that they use it at home on people. Insects are known to collect sensory signals such as carbon dioxide, odors and heat to locate people. But the results show an intriguing correlation, Hoy said. Although the results do not offer new pathways for mosquito control, they open the door for the development of highly sensitive directional microphones and hearing aids that use thin hairs that perceive the velocity of airborne particles as they are pushed by sound waves.