Leafhopper males compensate for unclear directional cues in vibration-mediated mate localization.

Ambient noise and transmission properties of the substrate pose challenges in vibrational signal-mediated mating behavior of arthropods, because vibrational signal production is energetically demanding. We explored implications of these challenges in the leafhopper Aphrodes makarovi (Insecta: Hemiptera: Cicadellidae) by exposing males to various kinds of vibrational noise on a natural substrate and challenging them to find the source of the female playback. Contrary to expectations, males exposed to noise were at least as efficient as control males on account of similar searching success with less signaling effort, while playing back male-female duets allowed the males to switch to satellite behavior and locate the target without signaling, as expected. We found altered mitochondrial structure in males with high signaling effort that likely indicate early damaging processes at the cellular level in tymbal muscle, but no relation between biochemical markers of oxidative stress and signaling effort. Analysis of signal transmission revealed ambiguous amplitude gradients, which might explain relatively low searching success, but it also indicates the existence of behavioral adaptations to complex vibrational environments. We conclude that the observed searching tactic, emphasizing speed rather than thorough evaluation of directional cues, may compensate for unclear stimuli when the target is near.

The Effect of Timing of Female Vibrational Reply on Male Signalling and Searching Behaviour in the Leafhopper Aphrodes makarovi.

Sexual communication in animals often involves duetting characterized by a coordinated reciprocal exchange of acoustic signals. We used playback experiments to study the role of timing of a female reply in the species-specific duet structure in the leafhopper Aphrodes makarovi (Hemiptera: Cicadellidae). In leafhoppers, mate recognition and location is mediated exclusively by species- and sex-specific substrate-borne vibrational signals and a female signal emitted in reply to male advertisement calls is essential for recognition and successful location of the female. In A. makarovi, males have to initiate each exchange of vibrational signals between partners, and in a duet the beginning of a female reply overlaps the end of the male advertisement call. Results of playback treatments in which female replies were delayed and did not overlap with the male call revealed that in order to trigger an appropriate behavioural response of the male, female reply has to appear in a period less than 400 ms after the end of the initiating male call. Results also suggest that males are not able to detect a female reply while calling, since female reply that did not continue after the end of male call triggered male behaviour similar to behaviour observed in the absence of female reply. Together, our results show that vibrational duets are tightly coordinated and that the species-specific duet structure plays an important role in mate recognition in location processes.