AUDITORY RECEPTOR RESPONSE TO A CONTINUOUS SERIES OF SHORT CLICKS IN NOCTUID MOTHS (NOCTUIDAE, LEPIDOPTERA)
Responses of the tympanic auditory A1 receptor to a series of short acoustic clicks were recorded in noctuid moth Amphipyra perflua F. The signals used for stimulation were similar to the own clicks of a moth. The aim of the study was to obtain the dependence of receptor response on the repetition rate of clicks. In the range from 1 to 30 pulses per second the A1 receptor demonstrated the same stable response to every click. At repetition rates being higher than 30 1/s the monotonic decrease in response from 3 to 1 spike per click was observed. Such a decrease is equal to the auditory threshold rise by 10-12 dB. This effect should not worsen significantly the efficacy of the moth echolocational system. In view of defensive behavior the observed decrease in sensitivity can have an adaptive significance: frequently repeated low-amplitude signals would be expected from a distant bat attacking some other prey and thus not threatening the moth.