FREQUENCY AS A RELEASER IN THE COURTSHIP SONG OF 2 CRICKETS, GRYLLUS-BIMACULATUS (DE GEER) AND TELEOGRYLLUS-OCEANICUS - A NEUROETHOLOGICAL ANALYSIS

1. The courtship behavior of male field crickets, Gryllus bimaculatus (De Geer) and Teleogryllus oceanicus, is a complex, multimodal behavio ral act that involves acoustic signals (a courtship song; Fig. 1A,B). The dominant frequency is 4.5 kHz for 7: oceanicus song (Fig. 1A) and 13.5 kHz for G. bimaculatus (Fig. 1B). 2. When courting males are depr ived of their courtship song by wing amputation, their courtship succe ss declines markedly but is restored when courting is accompanied by t ape-recordings of their courtship songs or a synthetic courtship song with only the dominant frequency of the natural song; other naturally occurring frequency components are ineffective for restoring mating su ccess (Figs. 4, 5). 3. It has been suggested that an identified audito ry interneuron, AN2, plays a critical role in courtship success. Chron ic recordings of AN2 in an intact, tethered female show that AN2's res ponse to the natural courtship song and synthesized songs at 4.5 and 1 3.5 kHz is similar in T. oceanicus. By contrast, in G. bimaculatus, AN 2's response to the natural courtship song and synthesized song at 13. 5 kHz, but not at 4.5 kHz, is similar (Figs. 2,3). 4. In behavioral ex periments, playback of a 30 kHz synthetic courtship song in G. bimacul atus does not restore courtship success, yet this same stimulus elicit s as strong a response from AN2 as does the normal courtship song (Fig . 6). Thus, contrary to earlier work by others, we conclude AN2 is not , by itself, a critical neural link in the courtship behavior of these two species of crickets.