The Long and Short of Hearing in the Mosquito Aedes aegypti

• Published in: Current biology Vol. 29; no. 4; pp. 709 - 714.e4
• Main Authors: Menda, Gil, Nitzany, Eyal I., Shamble, Paul S., Wells, Amelia, Harrington, Laura C., Miles, Ronald N., Hoy, Ronald R.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 18.02.2019
• Subjects: Aedes - physiology; Aedes aegypti; Animals; Auditory Perception; biomimicry; far-field hearing; Female; Flight, Animal; hearing; Hearing - physiology; Johnston’s organ; Male; mosquitoes; mosquitoes; hearing; Johnston’s organ; Aedes aegypti; far-field hearing; biomimicry
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2019.01.026

Mating behavior in Aedes aegypti mosquitoes occurs mid-air and involves the exchange of auditory signals at close range (millimeters to centimeters) [1–6]. It is widely assumed that this intimate signaling distance reflects short-range auditory sensitivity of their antennal hearing organs to faint flight tones [7, 8]. To the contrary, we show here that male mosquitoes can hear the female’s flight tone at surprisingly long distances—from several meters to up to 10 m—and that unrestrained, resting Ae. aegypti males leap off their perches and take flight when they hear female flight tones. Moreover, auditory sensitivity tests of Ae. aegypti’s hearing organ, made from neurophysiological recordings of the auditory nerve in response to pure-tone stimuli played from a loudspeaker, support the behavioral experiments. This demonstration of long-range hearing in mosquitoes overturns the common assumption that the thread-like antennal hearing organs of tiny insects are strictly close-range ears. The effective range of a hearing organ depends ultimately on its sensitivity [9–13]. Here, a mosquito’s antennal ear is shown to be sensitive to sound levels down to 31 dB sound pressure level (SPL), translating to air particle velocity at nanometer dimensions. We note that the peak of energy of the first formant of the vowels of the human speech spectrum range from about 200–1,000 Hz and is typically spoken at 45–70 dB SPL; together, they lie in the sweet spot of mosquito hearing. [Display omitted] •The mosquito Aedes aegypti hears sound over surprisingly long distances•Behavioral and physiological experiments confirm a range of audibility up to 10 m•Ae. aegypti is sensitive to sound frequencies of 150–500 Hz•The vowel sounds of human speech contain energy at 150–500 Hz Previous behavioral work shows that mosquitos hear sounds just a few centimeters away. Menda et al.’s behavioral and physiological experiments show that Aedes aegypti mosquitos can hear up to 10 m away. Notably, the vowel sounds of human speech contain frequencies that are spoken at levels which, in principle, are audible to mosquitos.