Recent insights on the mechanisms of frequency discrimination in cicadas (Hemiptera, Cicadoidea).

Abstract

Mate finding in cicadas is usually mediated by acoustic communication. Males produce a loud acoustic signal that is used to guide females toward singing males. The calling songs are frequently complex with changes in rhythm, amplitude modulation and, in many species, frequency modulation. Therefore, it is likely that the auditory organ encode some of those characteristics and that the nervous system may process the information and extract some species‐specific parameters. The tympanic vibrations are transferred to the onion‐shaped auditory organ, localized at some distance from the tympanum within the auditory capsule, through a stiff schlerotized apodeme. This configuration has raised problems to the understanding of how the different frequencies of the song, that Fonseca et al. (2000) have shown to be finely encoded at the level of the auditory interneurons in the cicada Tettigetta josei, are passed on to the auditory organ by the structures of the receptor. Using biophysical, electrophysiological, and anatomical measurements from the receptor structures of the cicada Tettigetta josei, a functional model that may allow for the above‐mentioned frequency discrimination will be presented [Fonseca, P.J., Münch, D., and Hennig, R.M., “How cicadas interpret acoustic signals,” Nature 405,297–298 (2000)].