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.

Polajnar J ，Kuhelj A ，Janža R ，Žnidaršič N ，Simčič T ，Virant-Doberlet M ... -  《Scientific Reports》

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

Kuhelj A ，de Groot M ，Blejec A ，Virant-Doberlet M ... -  《PLoS One》

Vibration-guided mate searching in treehoppers: directional accuracy and sampling strategies in a complex sensory environment.

Animal movement decisions involve an action-perception cycle in which sensory flow influences motor output. Key aspects of the action-perception cycle involved in movement decisions can be identified by integrating path information with measurement of environmental cues. We studied mate searching in insects for which the primary sensory cues are mechanical vibrations traveling through the tissues of living plants. We mapped search paths of male thornbug treehoppers locating stationary females through an exchange of vibrational signals. At each of the males' sampling locations, we used two-dimensional laser vibrometry to measure stem motion produced by female vibrational signals. We related properties of the vibrational signals to the males' movement direction, inter-sample distance and accuracy. Males experienced gradients in signal amplitude and in the whirling motion of the plant stem, and these gradients were influenced to varying degrees by source distance and local stem properties. Males changed their sampling behavior during the search, making longer inter-sample movements farther from the source, where uncertainty is higher. The primary directional cue used by searching males was the direction of wave propagation, and males made more accurate decisions when signal amplitude was higher, when time delays were longer between the front and back legs, and when female responses were short in duration. The whirling motion of plant stems, including both the eccentricity and the major axes of motion, is a fundamental feature of vibrational environments on living plants, and we show for the first time that it has important influences on the decisions of vibrationally homing insects.

Gibson JS ，Cocroft RB 《-》

The process of pair formation mediated by substrate-borne vibrations in a small insect.

The ability to identify and locate conspecifics depends on reliable transfer of information between emitter and receiver. For a majority of plant-dwelling insects communicating with substrate-borne vibrations, localization of a potential partner may be a difficult task due to their small body size and complex transmission properties of plants. In the present study, we used the leafhopper Scaphoideus titanus as a model to investigate duetting and mate searching associated with pair formation. Studying these insects on a natural substrate, we showed that the spatio-temporal structure of a vibrational duet and the perceived intensity of partner's signals influence the mating behaviour. Identification, localization and courtship stages were each characterized by a specific duet structure. In particular, the duet structure differed in synchronization between male and female pulses, which enables identification of the partner, while the switch between behavioural stages was associated with the male-perceived intensity of vibrational signals. This suggests that males obtain the information about their distance from the female and optimize their strategy accordingly. More broadly, our results show that even in insects smaller than 1cm, vibrational signals provide reliable information needed to find a mating partner.

Polajnar J ，Eriksson A ，Rossi Stacconi MV ，Lucchi A ，Anfora G ，Virant-Doberlet M ，Mazzoni V ... -  《-》

Secondary spectral components of substrate-borne vibrational signals affect male preference.

Animal sexual signals contain information about both compatibility and quality of the signaller, but combined with influence of the signalling medium, the complexity of mate selection makes it difficult to separate different components of this process. We approached the problem of teasing apart different functions of sexual signals by using the planthopper Hyalesthes obsoletus, which uses unimodal vibrational communication, as a model. Vibrational signals are known to encode information about identity in their temporal pattern, while a useful cue for quality may reside in their spectral properties. In this study, we demonstrate a connection between spectral properties and attractiveness of female signals based on male behavioural response to signal playback. Artificially increasing the amplitude of high-frequency components increases signal attractiveness and vice versa, which indicates that spectral properties could function as an index of quality. Presence of high-frequency spectral components might indicate a larger or healthier individual, but direct connection with female fitness is not yet clear. In addition, we found that H. obsoletus males are able to exploit female pulses as directional cues and can discriminate between female signals of different attractiveness coming from spatially separated sources.

Mazzoni V ，Polajnar J ，Virant-Doberlet M 《-》