Phonotaxis to individual rhythmic components of a complex cricket calling song

Summary

The calling song ofTeleogryllus oceanicus consists of a chirp section and a trill section. We tested the phonotactic attractiveness to femaleT. oceanicus of the chirp and trill components of the song by permitting crickets to choose between synthetic song models in two-choice behavioral assays.

In a flight phonotaxis assay tethered flying crickets were simultaneously offered two different song models from loudspeakers located to the left and right. Song preference was indicated by postural changes associated with steering attempts. In the flight assay females preferred a song derived from the chirp component of the normal song pattern to one derived from the trill component (Figs. 3, 4A). They also preferred a song which consisted of 100% chirp over the normal song pattern, which is only 16% chirp (Fig. 6A). And, they preferred the normal song pattern to a chirp-free, trill-derived model (Fig. 5A). Two other song models, in which the percent of time occupied by the chirp was approximately twice normal, were also preferred to the normal pattern (Fig. 7). Thus, the chirp section of the song was more attractive than the trill section. Although the two components differed in their relative attractiveness, either was preferred to a heterospecific song model (Figs. 8A, 9A).

Five of these experiments were also performed using a walking phonotaxis assay. Crickets were released in an arena in which two loudspeakers broadcast different song models. Song preferences were indicated by the relative number of times each loudspeaker was approached. For three experiments (Figs. 4, 5, 8) the results obtained with the walking assay were qualitatively similar to those obtained with the flight assay. In two experiments there was no apparent discrimination of the songs in the walking assay, although the songs were discriminated in the flight assay (Figs. 6, 9). Possible reasons for the differences observed between the assays are discussed.