Female preferences for acoustic and olfactory signals during courtship: male crickets send multiple messages

Males can produce complex sexual signals, often in different sensory modalities. The information conveyed by multiple signals, and the degree to which multiple signals interact in influencing female mating decisions, is not well understood. Male crickets produce 2 signals during courtship, an acoustic signal or courtship song, and a contact olfactory signal in the form of a blend of hydrocarbon compounds secreted onto the cuticle. We used selection analyses to examine the form of female preferences acting on these 2 sexual signals in the Australian field cricket Teleogryllus oceanicus. Both signals were subject to significant nonlinear preferences. Cuticular hydrocarbon profiles were subject to disruptive female preferences, with males exhibiting average cuticular hydrocarbon profiles experiencing the lowest mating success. In contrast, courtship song was subject to directional preferences, whereby males with high sound content in the trill element of the song, and to a lesser extent the chirp element, had the greatest mating success. Across males, the attractiveness of cuticular hydrocarbons was not correlated with the attractiveness of courtship songs, indicating that these signals convey multiple messages. Previous work on T. oceanicus suggests that courtship song may be a condition-dependent signal of good genes, whereas cuticular hydrocarbon profiles may provide cues to genetic compatibility. We found that olfactory and acoustic cues had equal weight in predicting the probability of male mating success. Interactions between cuticular hydrocarbon and courtship song attractiveness may help explain the maintenance of genetic variation found in these sexual traits.