Relative Amplitude of Courtship Song Chirp and Trill Components Does Not Alter Female Teleogryllus oceanicus Mating Behavior

Abstract

Low-amplitude acoustic signals intended for short-range communication, often called soft songs, remain poorly studied, especially among acoustically communicating invertebrates. Some insects do employ low-amplitude acoustic signals, but it remains unclear what the specific function, if any, is of quietness per se. Male Teleogryllus oceanicus, or Pacific field crickets, produce a two component, short-distance courtship song consisting of a high-amplitude series of chirps followed by a lower-amplitude trill. We investigated whether female T. oceanicus prefer to mate with males that sing courtship songs containing trill components that are equally as loud as (−0 dB) or quieter than (−3 dB and −10 dB) the loudest chirp (90 dB). We found no evidence that modifying trill amplitude affects female mate preference. We did, however, find that previously unmated females were faster to mount males than were females that had mated once before. Previous mating status showed no significant interaction with trill amplitude. What, if any, function of low-amplitude components of field cricket courtship song remains to be determined.