Energetic cost of vibrational signalling in a leafhopper

Communication via substrate-borne vibrations is the most widespread form of acoustic communication in arthropods. However, remarkably little is known about physiological sources of selection on vibrational communication systems, in particular those underlying mate choice and male competition. Here, we studied the energetic cost of vibrational signalling in the leafhopper Aphrodes makarovi (Hemiptera: Cicadellidae). We measured O₂ consumption of a single male for 15-30 min using the closed-bottle method and a lifetimebased optode, while we recorded emitted vibrational signals with a laser vibrometer. Males were emitting three types of vibrational signals (advertisement calls, masking signals and pulse signals), and the respiration rate was significantly positively correlated with the cumulative signalling time. Our results showed that vibrational signalling was around 12.4 times energetically more demanding than resting. Furthermore, production of masking signals emitted in rivalry situations was as energetically demanding as production of advertisement calls used in sexual communication between partners. We also assessed the effect of calling effort on male survival. We determined calling effort by playback experiments once every week of male's adult life until death. The average male longevity was 50 days, and survival was negatively correlated with the number of emitted advertisement calls, calling rate and calling time in early life. Considering that in mating systems based on vibrational signals, communication occurs in a changing social environment, more detailed studies on indirect costs of signalling in such systems may provide new insights into mechanisms that lead to adaptive plasticity in male sexual behaviour.