A role for acoustic distortion in novel rapid frequency modulation behaviour in free-flying male mosquitoes.
We describe a new stereotypical acoustic behaviour by male mosquitoes in response to the fundamental frequency of female flight tones during mating sequences. This male-specific free-flight behaviour consists of phonotactic flight beginning with a steep increase in wing-beat frequency (WBF) followed by rapid frequency modulation (RFM) of WBF in the lead up to copula formation. Male RFM behaviour involves remarkably fast changes in WBF and can be elicited without acoustic feedback or physical presence of the female. RFM features are highly consistent, even in response to artificial tones that do not carry the multi-harmonic components of natural female flight tones. Comparison between audiograms of the robust RFM behaviour and the electrical responses of the auditory Johnston's organ (JO) reveals that the male JO is tuned not to the female WBF per se but, remarkably, to the difference between the male and female WBFs. This difference is generated in the JO responses as a result of intermodulation distortion products (DPs) caused by non-linear interaction between male-female flight tones in the vibrations of the antenna. We propose that male mosquitoes rely on their own flight tones in making use of DPs to acoustically detect, locate and orientate towards flying females. We argue that the previously documented flight-tone harmonic convergence of flying male and female mosquitoes could be a consequence of WBF adjustments so that DPs generated through flight-tone interaction fall within the optimal frequency ranges for JO detection.
Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, UK p.simoes@brighton.ac.uk i.russell@brighton.ac.uk.
Patrício M V
PM
Simões
Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, UK.
Robert A
RA
Ingham
Department of Agriculture, Health and Environment, Natural Resources Institute, University of Greenwich, Chatham, Kent ME4 4TB, UK.
Gabriella
G
Gibson
Sensory Neuroscience Research Group, School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton BN2 4GJ, UK p.simoes@brighton.ac.uk i.russell@brighton.ac.uk.
Ian J
IJ
Russell
D000162:Acoustics; D000818:Animals; D001307:Auditory Perception; D009033:Culicidae / Q000502:physiology*; D055724:Electrophysiological Phenomena; D005426:Flight, Animal; D008297:Male; D009949:Orientation; D014921:Wings, Animal / Q000502:physiology
Acoustic behaviour; Culex quinquefasciatus; Distortion products; Insect hearing; Johnston's organ; Mating behaviour; Phonotaxis