@article {57944, title = {Sensory evolution of hearing in tettigoniids with differing communication systems}, journal = {Journal of Evolutionary Biology}, volume = {27}, year = {2014}, month = {Jan-01-2014}, pages = {200 - 213}, abstract = {

In Tettigoniidae (Orthoptera: Ensifera), hearing organs are essential in mate detection. Male tettigoniids usually produce calling songs by tegminal stridu- lation, whereas females approach the males phonotactically. This unidirec- tional communication system is the most common one among tettigoniids. In several tettigoniid lineages, females have evolved acoustic replies to the male calling song which constitutes a bidirectional communication system. The genus Poecilimon (Tettigoniidae: Phaneropterinae) is of special interest because the ancestral state of bidirectional communication, with calling males and responding females, has been reversed repeatedly to unidirec- tional communication. Acoustic communication is mediated by hearing organs that are adapted to the conspecific signals. Therefore, we analyse the auditory system in the Tettigoniidae genus Poecilimon for functional adapta- tions in three characteristics: (i) dimension of sound-receiving structures (tympanum and acoustic spiracle), (ii) number of auditory sensilla and (iii) hearing sensitivity. Profound differences in the auditory system correlate with uni- or bidirectional communication. Among the sound-receiving structures, the tympana scale with body size, whereas the acoustic spiracle, the major sound input structure, was drastically reduced in unidirectional communicating species. In the unidirectional P. ampliatus group, auditory sensilla are severely reduced in numbers, but not in the unidirectional P. propinquus group. Within the P. ampliatus group, the number of auditory sensilla is further reduced in P. intermedius which lost acoustic signalling due to parthenogenesis. The auditory sensitivity correlated with the size of the acoustic spiracle, as hearing sensitivity was better with larger spiracles, espe- cially in the ultrasonic range. Our results show a significant reduction in auditory structures, shaped by the differing sex roles during mate detection.

}, keywords = {animal communication, insect hearing, regressive evolution, sensory ecology, sensory evolution, tympanal organ}, doi = {10.1111/jeb.2014.27.issue-110.1111/jeb.12294}, url = {http://doi.wiley.com/10.1111/jeb.2014.27.issue-1}, author = {Strau{\ss}, J. and Lehmann, A. W. and Gerlind U.C. Lehmann} } @article {57892, title = {Acoustic-induced motion of the bushcricket (Mecopoda elongata, Tettigoniidae) tympanum}, year = {2010}, keywords = {Acoustic resonance, insect hearing, trachea, Vibration measurements}, doi = {10.1007/s00359-010-0577-6}, url = {http://link.springer.com/10.1007/s00359-010-0577-6}, author = {Nowotny, Manuela and Hummel, Jennifer and Weber, Melanie and M{\"o}ckel, Doreen and K{\"o}ssl, Manfred} } @article {57891, title = {Processing of simple and complex acoustic signals in a tonotopically organized ear}, year = {2014}, abstract = {

Processing of complex signals in the hearing organ remains poorly understood. This paper aims to contribute to this topic by presenting investigations on the mechanical and neuronal response of the hearing organ of the tropical bushcricket species Mecopoda elongata to simple pure tone signals as well as to the conspecific song as a complex acoustic signal. The high-frequency hearing organ of bushcrickets, the crista acustica (CA), is tonotopically tuned to frequencies between about 4 and 70 kHz. Laser Doppler vibrometer measurements revealed a strong and dominant low-frequency-induced motion of the CA when stimulated with either pure tone or complex stimuli. Consequently, the high-frequency distal area of the CA is more strongly deflected by low-frequency-induced waves than by high-frequency-induced waves. This low-frequency dominance will have strong effects on the processing of complex signals. Therefore, we additionally studied the neuronal response of the CA to native and frequency-manipulated chirps. Again, we found a dominant influence of low-frequency components within the conspecific song, indicating that the mechanical vibration pattern highly determines the neuronal response of the sensory cells. Thus, we conclude that the encoding of communication signals is modulated by ear mechanics.

}, keywords = {bushcricket, crista acustica, Electrophysiology, insect hearing, laser Doppler vibrometry, Tettigoniidae}, doi = {10.1098/rspb.2014.1872}, url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2014.1872https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2014.1872}, author = {Hummel, Jennifer and Wolf, Konstantin and K{\"o}ssl, Manfred and Nowotny, Manuela} } @article {57667, title = {Sound-induced tympanal membrane motion in bushcrickets and its relationship to sensory output}, year = {2011}, abstract = {

n the auditory system of bushcrickets, sound can reach the receptors via two different paths: (i) by acting on the outside of the tympana situated on both sides of each foreleg or (ii) through the acoustic trachea that opens at a spiracle on the thorax. While the spiracle is considered to be the main point of sound entry for higher audio and ultrasonic frequencies, the role of the tympana is still unclear. The tympana border the air-filled acoustic trachea as well as the fluid-filled haemolymph channel containing the receptor organs. To understand their role during sound transduction, the sound-induced neuronal response of the hearing organ was recorded in combination with measurement of tympanal membrane motion using laser-Doppler vibrometry. For far-field stimulation, the frequency of the most sensitive hearing (\∼16 kHz) matched the frequency of a pronounced maximum of tympanal membrane vibration. A second maximum of tympanum motion at lower frequencies (\∼7 kHz) was correlated with an increased nerve activity at higher intensities (\>70 dB sound pressure level, SPL). These correlations support the hypothesis of functional coupling between tympanum motion and nerve activity. When sound stimuli were applied locally, through either the tympanum or the spiracle, significant differences between tympanum motion and nerve activity were found. These discrepancies show that tympanum motion and neuronal response are not coupled directly and that there is no linear relationship with the applied SPL. Taken together, these data verify a functional, albeit indirect, coupling of tympanum motion and sensory cell activity for one of the pronounced vibration maxima, which appears to represent a resonance frequency of the tympanum.

}, keywords = {insect hearing, katydid, laser-Doppler vibrometer, Mecopoda elongata, spiracle, tympanal nerve}, doi = {10.1242/jeb.054445}, url = {http://jeb.biologists.org/cgi/doi/10.1242/jeb.054445}, author = {Hummel, J. and Kossl, M. and Nowotny, M.} } @article {57343, title = {Functional relevance of acoustic tracheal design in directional hearing in crickets}, journal = {The Journal of Experimental Biology}, volume = {219}, year = {2016}, month = {Mar-10-2017}, pages = {3294 - 3300}, abstract = {

Internally coupled ears (ICEs) allow small animals to reliably determine the direction of a sound source. ICEs are found in a variety of taxa, but crickets have evolved the most complex arrangement of coupled ears: an acoustic tracheal system composed of a large cross-body trachea that connects two entry points for sound in the thorax with the leg trachea of both ears. The key structure that allows for the tuned directionality of the ear is a tracheal inflation (acoustic vesicle) in the midline of the cross-body trachea holding a thin membrane (septum). Crickets are known to display a wide variety of acoustic tracheal morphologies, most importantly with respect to the presence of a single or double acoustic vesicle. However, the functional relevance of this variation is still not known. In this study, we investigated the peripheral directionality of three co-occurring, closely related cricket species of the subfamily Gryllinae. No support could be found for the hypothesis that a double vesicle should be regarded as an evolutionary innovation to (1) increase interaural directional cues, (2) increase the selectivity of the directional filter or (3) provide a better match between directional and sensitivity tuning. Nonetheless, by manipulating the double acoustic vesicle in the rainforest cricket Paroecanthus podagrosus, selectively eliminating the sound-transmitting pathways, we revealed that these pathways contribute almost equally to the total amount of interaural intensity differences, emphasizing their functional relevance in the system.

}, keywords = {acoustic communication, insect hearing, Internally coupled ear, laser Doppler vibrometry, Matched filters, Sound localization}, issn = {0022-0949}, doi = {10.1242/jeb.145524}, url = {http://jeb.biologists.org/lookup/doi/10.1242/jeb.145524https://syndication.highwire.org/content/doi/10.1242/jeb.145524https://syndication.highwire.org/content/doi/10.1242/jeb.145524}, author = {Arne K. D. Schmidt and Heiner R{\"o}mer} } @article {15287, title = {A comparative study of ultrasound-triggered behaviour in tiger beetles (Cicindelidae)}, journal = {Journal of Zoology}, volume = {251}, year = {2000}, month = {Jan-07-2000}, pages = {355 - 368}, abstract = {

This study examines the behavioural responses to ultrasound in 52 species from the family Cicindelidae using both tethered \Øight and non-\Øight assays. Tethered \Øying tiger beetles respond to trains of bat-like ultrasonic pulses with a short-latency, multi-component behaviour. There was no variation in the nature of the behavioural responses regardless of geographical distribution or phylogenetic position. Lowest mean behavioural thresholds lie predominantly between 30 and 45 kHz. Sensitivity, however, varies widely, and several species do not respond at all in these assays. The lowest thresholds for responders are most often between 70 and 80 dB SPL. Almost all subgenera of North American tiger beetles in the genus Cicindela have at least some species with low-threshold acoustic behaviour. The single exception is the large subgenus Cicindela where all species are completely unresponsive or have very high thresholds. There was little relationship between habitat and responsiveness to ultrasound, but there is a strong correlation with seasonal activity \± species with adults active in the spring and autumn (all in the subgenus Cicindela )do not show ultrasound-triggered behaviour whereas summer-active species generally do. Superimposing these data on a current phylogeny of the North American tiger beetles suggests that acoustic behaviour (and hearing) is a shared primitive trait among the taxa examined here and that there have been at least \Æve independent losses of this character.

}, keywords = {Cicindela, defensive behaviour, evolution, insect hearing, phylogeny}, issn = {0952-8369}, doi = {10.1111/jzo.2000.251.issue-310.1111/j.1469-7998.2000.tb01086.x}, url = {http://www.blackwell-synergy.com/toc/jzo/251/3}, author = {Yager, David D. and Cook, Aaron P. and Pearson, David L. and Spangler, Hayward G.} }