Chirp rate variability in male song ofEphippigerida taeniata (Orthoptera: Ensifera)

Abstract

Variability in the chirp rate of the male song of the ephippigerine species Ephippigerida taeniata during intraspecific communication was investigated in the laboratory. Conspecific chirps were used as auditory stimuli. The stimulus rate was controlled by computer. Experiments were carried out at 19, 27, and 35°C. Acoustically isolated males of E. taeniata sang with a relatively constant chirp rate, which depended on the ambient temperature. Chirp rate significantly increased with rising temperature from 19 to 27°C, whereas at 35°C the chirp rate did not differ significantly from that at 2 7°C. Male chirp rates were affected by stimulus rates. Males significantly increased their chirp rate in response to increasing stimulus rates at temperatures of 19 and 27°C. At 35°C the increase in the chirp rate was not significant. At 27 and 35°C males sang with a higher chirp rate than the stimulus rate within a certain range. Evaluating stimulus and response chirp pattern when the males increased their chirp rate in response to the stimulus rate showed that an alternation pattern was established. More than 50% of the male chirps occurred at a characteristic time range at around 40% of the interstimulus interval, which was slightly affected by temperature.