Selective phonotaxis in Tettigonia cantans and T. viridissima in song recognition and discrimination

Abstract

The selectivity of female phonotaxis in Tettigonia cantans and T. viridissima was investigated on a Kramer treadmill, with respect to the specific differences in temporal pattern and spectrum of the songs of both species. In choice situations, both species preferred the conspecific song over the heterospecific one. The courses of both species were deflected by about 15–20° from the position of the conspecific song, that of T. viridissima being away from, that of T. cantans in the direction of the heterospecific song. In no-choice situations, song models with the temporal pattern of T. cantans did not attract T. viridissima. Models with the conspecific time pattern but heterospecific spectrum were as attractive as the conspecific model. In contrast, T. cantans was attracted by T. viridissima song presented alone. In choice situations, either spectral or temporal differences were sufficient for discrimination. The preference for the conspecific model gradually disappeared with stepwise reduction of its intensity and was reversed at −12 dB. Acoustic communication alone can serve species isolation in T. viridissima; however, premating isolation in T. cantans must involve other mechanisms. The orientation during the choice situations suggests a serial processing of song recognition and localization for the Tettigonia species.