SELECTIVE PHONOTAXIS IN TETTIGONIA CANTANS AND T-VIRIDISSIMA IN SONG RECOGNITION AND DISCRIMINATION

The selectivity of female phonotaxis in Tettigonia cantans and T. viri dissima nias investigated on a Kramer treadmill, with respect to the s pecific differences in temporal pattern and spectrum of the songs of b oth species. In choice situations, both species preferred the conspeci fic song over the heterospecific one. The courses of both species were deflected by about 15-20 degrees from the position of the conspecific song, that of T. viridissima being away from, that of T. cantans in t he direction of the heterospecific song. In no-choice situations, song models with the temporal pattern of T. cantans did not attract T. vir idissima, Models with the conspecific time pattern but heterospecific spectrum were as attractive as the conspecific model. In contrast, T. cantans mas attracted by T. viridissima song presented alone. In choic e 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 i n T. viridissima; however, premating isolation in T. cantans must invo lve other mechanisms. The orientation during the choice situations sug gests a serial processing of song recognition and localization for the Tettigonia species.