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•A circular arena was used to evaluate aggregation in woodlice.•We assessed substrate-borne vibrations as the principal factor.•A. officinalis reacted significantly to ...micro-vibrations, unlike A. vulgare.•The capability of A. officinalis to produce vibrations might be involved.
Gregarious behavior and aggregative phenomena among conspecifics in woodlice are thought to be a form of evolutionary adaptation to the terrestrial environment which has given these animals multiple advantages, e.g., against desiccation and predation. The reasons behind these phenomena, however, have not fully been clarified yet. This exploratory study has the aim to assess displacement and aggregation state relatively to the presence of substrate-borne vibrations in two different species of terrestrial isopods. To this goal, a circular arena was used to collect data from adult individuals of Armadillo officinalis, a stridulating species, and Armadillidium vulgare, a non-stridulating species, both exposed and non-exposed to micro-vibrations. Our results showed that exposed individuals of A. officinalis significantly react to micro-vibrations positioning themselves preferentially far from the vibrational source compared to non-exposed individuals of the same species. Furthermore, both the number of aggregates and of isolated subjects significantly increase in the presence of substrate-borne vibrations than in the absence of micro-vibrations. No statistically significant association with substrate-borne vibrations was found for A. vulgare for both placement and number of aggregates and of isolated subjects. Unlike A. vulgare, A. officinalis appears very sensitive to micro-vibrations which seem to represent a source of disturbance or potential danger. Substrate-borne vibrations seem to affect the capability of this species to aggregate leading to a greater number of aggregates and isolated subjects as if animals were a bit disoriented. This behavior might be related to a possible capability of this species to use micro-vibrations for inter- and intraspecific communication.
Selection on advertisement signals arises from interacting sources including female choice, male-male competition, and the communication channel (i.e., the signaling environment). To identify the ...contribution of individual sources of selection, we used previously quantified relationships between signal traits and each putative source to predict relationships between signal variation and fitness in Enchenopa binotata treehoppers (Hemiptera: Membracidae). We then measured phenotypic selection on signals and compared predicted and realized relationships between signal traits and mating success. We recorded male signals, then measured lifetime mating success at two population densities in a realistic environment in which sources of selection could interact. We identified which sources best predicted the relationship between signal variation and mating success using a multiple regression approach. All signal traits were under selection in at least one of the two breeding seasons measured, and in some cases selection was variable between years. Female preference was the strongest source of selection shaping male signals. The E. binotata species complex is a model of ecological speciation initiated by host shifts. Signal and preference divergence contribute to behavioral isolation within the complex, and the finding that female mate preferences drive signal evolution suggests that speciation in this group results from both ecological divergence and sexual selection.
Predicting how insects will react to future thermal conditions requires understanding how temperature currently affects insect behavior, from performance traits to those involved in mating and ...reproduction. Many reproductive behaviors are thermally-sensitive, but little is known how temperature affects the behaviors used to find mates and coordinate mating. Here, we investigate how temperature influences courtship activity in two sympatric species of Enchenopa treehoppers (Hemiptera: Membracidae). Enchenopa use substrate-borne vibrational signals exchanged in male-female duets to facilitate pair formation prior to mating. In a controlled laboratory setting, we assessed the likelihood of males and females to produce courtship signals across a range of ecologically relevant temperatures. We found that changes in courtship activity across temperatures differed between the two species. We also found sex differences within species: in one species males were more likely to signal at higher temperatures, while in the other species females were more likely to signal at higher temperatures. Our results suggest that sex-specific responses to temperature may constrain mating to narrower ranges of temperatures. Furthermore, sympatric species may respond differently to changes in thermal variation despite sharing similar climactic history.
•Models to automatically detect and indentify leafhopper vibrational male calls were developed.•Call features included linear prediction cepstral coefficients.•Features were classified by a ...multilayer perceptron and Gaussian Mixture Model.•Autonomous system (AS) also played back female reply and established a duet with the live male.•Results showed that AS mimicking a duetting female attracted males to the source.
In leafhoppers that are among the most important vectors of plant diseases, mate recognition and location are mediated exclusively by species- and sex-specific vibrational signals exchanged in precisely coordinated duets. These pests are currently managed primarily by insecticide treatments, however, current legislation and consumers’ concerns and demands require that the risks and impacts of pesticides be reduced. We present a proof-of-concept low-cost autonomous digital processing system (AS), capable of recognizing the male calls of the leafhopper Aphrodes bicincta “Dragonja” and generating female replies. Such a device could be used as a vibrational trap. We chose this species since its duet structure is complex, with the female replies having to appear in short (47–175ms) intervals between continuously repeated elements in the male call in order to trigger male searching behaviour. The AS male call recognition algorithm is based on linear prediction cepstral coefficient (LPCC) feature vectors and a multilayer perceptron classifier (MLP). To prevent the noise-based feature vectors from feeding into the classifier, a bandwidth-limited linear prediction call activity detector based on spectrum peak tracking was designed. We tested the efficiency of the AS in behavioural experiments with live males. The MLP classification method successfully classified vibrational calls of male A. bicincta “Dragonja” from background noise. The fast real time identification enabled a synchronized playback of female vibrational reply with latencies as short as 130ms. This mimicking of a duetting female by autonomous system also attracted the males to the source of the female reply. The AS is also a useful tool to enable further studies of vibrational duets that are needed to develop effective alternative control strategies.
•Scaphoideus titanus leafhoppers rely on vibrations in sexual communication.•Stages of mating behaviour are guided by male perception of vibrational cues.•Even small insects can extract information ...about location from vibrational signals.•Signalling is optimized to achieve either accuracy or speed, depending on context.
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.
The recent description of a new vibrational mating disruption method to control the leafhopper Scaphoideus titanus Ball opened questions about its possible application to other leafhopper pests. ...Since the prerequisite for the method's successful application is a deep knowledge of the species mating behavior and the exact role of associated signals, we conducted behavioral assays on the green leafhopper Empoasca vitis Göthe, a pest of grapevine and other crops in Europe and Asia. Laser vibrometer recordings of single and paired individuals (male and female) during a 24‐h period enabled us to detect and describe 2 male and 1 female signal. The pair formation starts when the female replies to a male call and a duet is established, then it continues through 2 different behavioral stages: Location and Courtship. The proper courtship begins only when the male locates the female. The latter is characterized by a significant change in temporal parameters that regards both the signals and the duet structure. Although the male calling activity and the female replying rate were the same during the 24 h, a lower number of matings was recorded during the night. We discuss the possible role of vision and of the species ecology as factors of reproductive success and mating strategy. Our conclusion is that the mechanical mating disruption technique seems feasible for future application to this species.
Research into vibrational communication is becoming increasingly important as we discover more species using vibrational signals in different types of behavior. Males of the solitary red mason bee, ...Osmia bicornis, are known to use vibrations in female choice, where the females not only evaluate a male’s fitness through their vibrational signal but also use them to distinguish between males of different origins. This was shown conclusively via bioassays, in which females from Germany rejected English males unless they were imbued with an artificial German signal and vice versa. However, an investigation into which parameters of the signal might differ between species and populations has been lacking so far. We therefore recorded O. bicornis as well as O. cornuta males from Germany, England, and Denmark using a laser vibrometer and analyzed the recordings using the software Spike to measure frequency, modulation range, and average pulse duration in each signal. Our results clearly showed significant differences in the signal between O. bicornis and O. cornuta males in all three parameters measured. O. bicornis populations from Germany and Denmark surprisingly also differed significantly in frequency and modulation range, with England lying in between the two. We believe that the females probably use another signal parameter that we have not evaluated yet to make their mate choice. This leaves us with the question of why the observed signal parameters differ between Germany and Denmark. From our knowledge about the system to date, we believe that we are looking at the first steps of speciation in this system and further study could help us with new insights into evolutionary processes in the future.
Sexual selection acting on small initial differences in mating signals and mate preferences can enhance signal–preference codivergence and reproductive isolation during speciation. However, the ...origin of initial differences in sexual traits remains unclear. We asked whether biotic environments, a source of variation in sexual traits, may provide a general solution to this problem. Specifically, we asked whether genetic variation in biotic environments provided by host plants can result in signal–preference phenotypic covariance in a host-specific, plant-feeding insect. We used a member of the Enchenopa binotata species complex of treehoppers (Hemiptera: Membracidae) to assess patterns of variation in male mating signals and female mate preferences induced by genetic variation in host plants. We employed a novel implementation of a quantitative genetics method, rearing field-collected treehoppers on a sample of naturally occurring replicated host plant clone lines. We found remarkably high signal–preference covariance among host plant genotypes. Thus, genetic variation in biotic environments influences the sexual phenotypes of organisms living on those environments in a way that promotes assortative mating among environments. This consequence arises from conditions likely to be common in nature (phenotypic plasticity and variation in biotic environments). It therefore offers a general answer to how divergent sexual selection may begin.
ABSTRACT Subterranean animals are limited in mobility and have reduced sensory ability due to living underground, and therefore are presented with a challenge to communicate. One solution is to use ...seismic signalling, by head drumming, to convey species-specific information. The lesser blind mole rats(Nannospalax sp.) are obligate subterranean rodents known for their remarkable chromosomal variation. In the present study, we investigated whether the structure of seismic signalling is different between the two species found in Turkey, Nannospalax leucodon and the N. xanthodon and whether it is associated with ecological, sex, temporal and chromosomal peculiarities. A cytotype of N. leucodon(2n=56) and three cytotypes of N. xanthodon,(2n=38, 52 and 60) were used in the study. We observed no seismic signalling in N. leucodon. In N. xanthodon, the cytotype 2n=60 had faster rate of signalling in comparison to two other cytotypes(2n=38 and 2n=52), and the cytotypes also differed significantly in the structural components of their signals. There was no difference in signal pattern between different fundamental number variations within cytotypes. We observed temporal variation in seismic signals, but did not found any difference in signalling between the sexes, suggesting the signals are not used for mate recognition. In addition, the signalling structure was not associated with the climate and the soil types of the habitat of origin. We suggest that seismic communication by drumming may be used to recognize conspecifics within the same cytotype or species.
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