Audition in the Desert Locust: Behavioural and Neurophysiological Studies

Abstract

ABSTRACT The auditory responses of the desert locust Schistocerca gregaria were tested using electrophysiological and behavioural methods. The electrical response of the tympanal nerve to pure tone stimuli showed maximum sensitivity between 3 and 5-5 kcyc/sec. The response was the same in both sexes. The flight behaviour was tested as function of pure tone stimuli and measured as the delay period, the number of insects reacting and the time they spent flying. The number of animals which began to fly after the various tones presented was in accordance with the electrophysiological results. The number of animals having a short delay period (under 30 sec) was considerably higher than in the controls for the various sound stimuli. The number of rounds flown (or time spent in flying) was the most affected parameter, although no systematic response was seen as a function of the tone ‘excitation’ by pure tone stimulus and ‘inhibition’ by ‘white’ noise. These two kinds of stimuli were presumably learned by the animal during successive repetition of the stimuli were presumably learned by the animal during successive repetition of the stimulation procedure. The usefulness of sound emission during flight and sound perception (by the hearing organ) was discussed. The auditory neural mechanism of the desert locust is presumably integrated with the visual mechanism for communication purposes between swarming animals.