Female preferences for male calling songs in the bladder grasshopper Bullacris membracioides

Male acoustic signals and the information they convey are often critical determinants of female mate choice. Bladder grasshoppers are one of numerous orthopteran taxa utilizing sound as the basis of courtship and ultimately mating. However, despite the extreme specializations for long-distance acoustic communication in this family, female mating preferences for male calls have not been previously investigated. Here we examine female acoustic responses to playbacks of male calls in Bullacris membracioides. Females were tested in three separate contexts, viz. response to conspecific calls of different individuals, response to degraded conspecific calls, and response to the calls of two heterospecifics. Female response was significantly correlated with seven of eight measured call features within B. membracioides, indicating sexual selection to be operating in this species. Females also responded to conspecific calls with degradation levels equivalent to a male calling 150 m away, but intensity equivalent to one at 25 m, identifying call amplitude rather than degradation as the factor limiting female response. However, as response decreased with increasing call degradation, signal quality remains a factor in female preference. Calls of the sister taxon B. intermedia were equally attractive to B. membracioides females as were conspecific calls, while the more distinct calls of B. serrata were less preferred than those of both B. membracioides and B. intermedia. This indicates a lack of discriminatory ability against a similar sounding heterospecific.