Insect hearing in the field

Abstract

1. For the bushcricketTettigonia viridissima a portable recording unit was constructed which enabled long-term extracellular recordings of single and identified auditory nerve cells in the field. Thus, aspects of sound reception and of directional hearing could be studied in the animal's natural environment. 2. The applicability of the technique is demonstrated in two examples. Remarkable hearing distances of 40–50 m were found in a grassland habitat; in denser bushland, these distances are reduced by about 20 m (Fig. 2). Once the stimulus is suprathreshold, the gross temporal structure of the song is well encoded in the activity of the omeganeuron even within a reflecting and scattering vegetation. 3. By recording the activity of a pair of directionally-sensitive interneurons in the field we have direct experimental evidence that directional information is provided at remarkable communication distances and strongly depends on the spatial configuration between sender and receiver (Fig. 3).