Search calls long duration puts the bat on the tympanate moth's radar. A new perspective on how Noctuoidea's auditory cells drive evasive manoeuvres

Abstract

The auditory stimulation method used in experiments on moth A cell(s) is generally believed to be adequate to characterise the encoding of echolocation signals. The stimulation method hosts, though, several bias. Their compounded effects can explain a range of discrepancies between the reported electrophysiological recordings and significantly alter the current interpretation. To test the hypothesis that the bias may significantly alter our current understanding of the moths auditory transducer characteristics, papers using the same auditory stimulation method and reporting on either spiking threshold or spiking activity of the moths A cells were analysed. The consistency of the reported data was assessed. A range of corrections issued from best practices and theoretical background were applied to the data in an attempt to re-interpret the data. We found that it is not possible to apply a posteriori corrections to all data and bias. However the corrected data indicates that the A cells spiking may be (i) independent of the repetition rate, (ii) maximum when detecting the long and low intensity pulses of the bat in searching mode, and (iii) steadily reduce as the bat closes on the moth. These observations raise the possibility that a fixed action pattern drives the mothss erratic evasive manoeuvres until the final moment. In depth investigation of the potential bias also suggest that the auditory transducers response may be constant for a larger frequency range than thought so far, and provide clues to explain the negative taxis in response to the searching batss calls detection.