Frequency tuning of individual auditory receptors in female mosquitoes (Diptera, Culicidae)

- Individual auditory receptors of mosquito are tuned to different frequencies.
- The frequency distribution of neurons is dominated by those tuned to frequencies between ∼75 and 125 Hz.
- We developed a novel positive feedback stimulation technique to test individual receptor tuning properties.
- We suggest that mosquitoes have the potential to analyse sounds into individual frequency components.

The acoustic sensory organs in mosquitoes (Johnston organs) have been thoroughly studied; yet, to date, no data are available on the individual tuning properties of the numerous receptors that convert sound-induced vibrations into electrical signals. All previous measurements of frequency tuning in mosquitoes have been based on the acoustically evoked field potentials recorded from the entire Johnston organ. Here, we present evidence that individual receptors have various frequency tunings and that differently tuned receptors are unequally represented within the Johnston organ. We devised a positive feedback stimulation paradigm as a new and effective approach to test individual receptor properties. Alongside the glass microelectrode technique, the positive feedback stimulation paradigm has allowed us to obtain data on receptor tuning in females from three mosquito species: Anopheles messeae, Aedes excrucians and Culex pipiens pipiens. The existence of individually tuned auditory receptors implies that frequency analysis in mosquitoes may be possible.