SONG PRODUCTION AND HEARINB SENSITIVITY IN BUSHCRICKET DERACANTHA ONOS

Pattern of the calling song,stridulatory mechanism and the hearing sensitivity of bushcricket Deracantha onos(Orthoptera,Tettigoniidae) were studied by acoustical analyses and neurophysiological techniques.Bushcrickets use an elytro-elytral mechanism in sound production:the denticulated vein (file) on the undersurface of the left elytron is rubbed by the inside edge (plectrum) of the right elytron at a rate of 30-33/s.No change in the activity of the motor neurons controlling the movement of the elytra was found after removing some teeth of the file.The file-train of pulses is the elementary component of the calling song of D.onos.Each file-train is composed of one elytra-opening pulse and 11-13 elytra-closing tooth pulses.Each tooth rubbing of the file against the plectrum elicits a damping oscillation called "tooth pulse" .The rate of the tooth pulses is about 450/s.The power spectrum of the song covers a wide frequency band from 6 to 30kHz with a peak at 12-14 kHz.The song intensity is about 110 dB L_p at a distance of 10cm from the animal.The best hearing sensitivity is in the range of 12-15kHz with the lowest threshold of 35 dB L_p.The narrow-band filter characteristic of hearing shows that D.onos possesses good frequency selectivity for species communication.