@article {57994, title = {Lateralization of Travelling Wave Response in the Hearing Organ of Bushcrickets}, year = {2014}, abstract = {

Travelling waves are the physical basis of frequency discrimination in many vertebrate and invertebrate taxa, including mammals, birds, and some insects. In bushcrickets (Tettigoniidae), the crista acustica is the hearing organ that has been shown to use sound-induced travelling waves. Up to now, data on mechanical characteristics of sound-induced travelling waves were only available along the longitudinal (proximal-distal) direction. In this study, we use laser Doppler vibrometry to investigate in-vivo radial (anterior-posterior) features of travelling waves in the tropical bushcricket Mecopoda elongata. Our results demonstrate that the maximum of sound-induced travelling wave amplitude response is always shifted towards the anterior part of the crista acustica. This lateralization of the travelling wave response induces a tilt in the motion of the crista acustica, which presumably optimizes sensory transduction by exerting a shear motion on the sensory cilia in this hearing organ.

}, doi = {10.1371/journal.pone.008609010.1371/journal.pone.0086090.g00110.1371/journal.pone.0086090.g00210.1371/journal.pone.0086090.g00310.1371/journal.pone.0086090.s00110.1371/journal.pone.0086090.s002}, url = {https://dx.plos.org/10.1371/journal.pone.0086090}, author = {Arun Palghat Udayashankar and K{\"o}ssl, Manfred and Nowotny, Manuela} } @article {57938, title = {Tonotopically Arranged Traveling Waves in the Miniature Hearing Organ of Bushcrickets}, year = {2012}, abstract = {

Place based frequency discrimination (tonotopy) is a fundamental property of the coiled mammalian cochlea. Sound vibrations mechanically conducted to the hearing organ manifest themselves into slow moving waves that travel along the length of the organ, also referred to as traveling waves. These traveling waves form the basis of the tonotopic frequency representation in the inner ear of mammals. However, so far, due to the secure housing of the inner ear, these waves only could be measured partially over small accessible regions of the inner ear in a living animal. Here, we demonstrate the existence of tonotopically ordered traveling waves covering most of the length of a miniature hearing organ in the leg of bushcrickets in vivo using laser Doppler vibrometery. The organ is only 1 mm long and its geometry allowed us to investigate almost the entire length with a wide range of stimuli (6 to 60 kHz). The tonotopic location of the traveling wave peak was exponentially related to stimulus frequency. The traveling wave propagated along the hearing organ from the distal (high frequency) to the proximal (low frequency) part of the leg, which is opposite to the propagation direction of incoming sound waves. In addition, we observed a non-linear compression of the velocity response to varying sound pressure levels. The waves are based on the delicate micromechanics of cellular structures different to those of mammals. Hence place based frequency discrimination by traveling waves is a physical phenomenon that presumably evolved in mammals and bushcrickets independently.

}, doi = {10.1371/journal.pone.0031008}, url = {https://dx.plos.org/10.1371/journal.pone.0031008}, author = {Arun Palghat Udayashankar and K{\"o}ssl, Manfred and Nowotny, Manuela} } @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 {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 {53507, title = {Synchronous, Alternating, and Phase-Locked Stridulation by a Tropical Katydid}, journal = {Science}, volume = {249}, year = {1990}, month = {Jun-07-1990}, pages = {55 - 58}, abstract = {

In the field the chirps of neighboring Mecopoda sp. (Orthoptera, Tettigoniidae, and Mecopodinae)malesarenormallysynchronized,butbetweenmoredistantindividuals the chirps are either synchronous or regularly alternating. The phase response to single-stimulus chirps depends on both the phase and the intensity of the stimulus. IterationofthePoincaremapofthephaseresponsepredictsavarietyofphase-locked synchronizationregimes,incudingperiod-doublingbifurcations,incloseagreement with experimental observations. The versatile acoustic behavior of Mecopoda encom- passesmostofthephenomenafoundinothersynchronizinginsectsandthusprovides ageneralmodelofinsectsynchronizationbehavio

}, issn = {0036-8075}, doi = {10.1126/science.249.4964.55}, url = {http://www.sciencemag.org/cgi/doi/10.1126/science.249.4964.55https://syndication.highwire.org/content/doi/10.1126/science.249.4964.55}, author = {Sismondo, E.} } @article {53154, title = {Evolutionarily conserved coding properties favour the neuronal representation of heterospecific signals of a sympatric katydid species}, journal = {Journal of Comparative Physiology A}, volume = {204}, year = {2018}, month = {Jan-10-2018}, pages = {859 - 872}, abstract = {

To function as a mechanism in premating isolation, the divergent and species-specific calling songs of acoustic insects must be reliably processed by the afferent auditory pathway of receivers. Here, we analysed the responses of interneurons in a katydid species that uses long-lasting acoustic trills and compared these with previously reported data for homologous interneurons of a sympatric species that uses short chirps as acoustic signals. Some interneurons of the trilling species respond exclusively to the heterospecific chirp due to selective, low-frequency tuning and \“novelty detection\”. These properties have been considered as evolutionary adaptations in the sensory system of the chirper, which allow it to detect signals effectively during the simultaneous calling of the sympatric sibling species. We propose that these two mechanisms, shared by the interneurons of both species, did not evolve in the chirper to guarantee its ability to detect the chirp under masking conditions. Instead we suggest that chirpers evolved an additional, 2-kHz component in their song and exploited pre-existing neuronal properties for detecting their song under masking noise. The failure of some interneurons to respond to the conspecific song in trillers does not prevent intraspecific communication, as other interneurons respond to the trill.

}, keywords = {Auditory processing, insects, Selective coding, signal detection, signal evolution}, issn = {0340-7594}, doi = {10.1007/s00359-018-1282-0}, url = {http://link.springer.com/10.1007/s00359-018-1282-0}, author = {Kostarakos, Konstantinos} } @article {51469, title = {First record of subfamily Mecopodinae (Orthoptera: Tettigoniidae) from Bihar along with description of Indian species}, journal = {Journal of Entomology and Zoology Studies 2017}, volume = {5}, year = {2017}, pages = {803-807}, chapter = {803}, abstract = {The present study was based on the specimens of Mecopodinae during the course of a survey from (01/03/2015 to 30/03/2015) from various agricultural areas of different regions of Bihar. Four male specimens were collected from different localities and identified as a species Mecopoda elongata elongata (Linnaeus, 1758) (Orthoptera: Tettigoniidae), was newly recorded from Bihar, India. The description was based on both conventional morphological and genitalic characters. The identifying features of the species were body very large, brown in color, tibial tympana opened on both the sides, stridulatory file having 98 teeth arranged in lamelliform manner under the side of left tegmen, male subgenital plate developed conically from region of bifurcation with short styli and hind femur \& tibiae very long and large. A morphological description, as well as detailed illustrations of this species is presented. Distribution and morphometrically data is also provided.}, keywords = {India, Mecopoda elongata elongata, new record, Orthoptera, Tettigoniidae}, author = {Mohd Kaleemulla Farooqi and Mohd Kamil Usmani} } @article {47616, title = {Maintaining acoustic communication at a cocktail party: heterospecific masking noise improves signal detection through frequency separation}, journal = {Journal of Experimental Biology}, volume = {216}, year = {2013}, month = {Oct-24-20132050}, pages = {4655 - 4665}, abstract = {

We examined acoustic masking in a chirping katydid species of the Mecopoda elongata complex due to interference with a sympatric Mecopoda species where males produce continuous trills at high amplitudes. Frequency spectra of both calling songs range from 1 to 80 kHz; the chirper species has more energy in a narrow frequency band at 2 kHz and above 40 kHz. Behaviourally, chirper males successfully phase-locked their chirps to playbacks of conspecific chirps under masking conditions at signal-to- noise ratios (SNRs) of \−8 dB. After the 2 kHz band in the chirp had been equalised to the level in the masking trill, the breakdown of phase-locked synchrony occurred at a SNR of +7 dB. The remarkable receiver performance is partially mirrored in the selective response of a first-order auditory interneuron (TN1) to conspecific chirps under these masking conditions. However, the selective response is only maintained for a stimulus including the 2 kHz component, although this frequency band has no influence on the unmasked TN1 response. Remarkably, the addition of masking noise at 65 dB sound pressure level (SPL) to threshold response levels of TN1 for pure tones of 2 kHz enhanced the sensitivity of the response by 10 dB. Thus, the spectral dissimilarity between masker and signal at a rather low frequency appears to be of crucial importance for the ability of the chirping species to communicate under strong masking by the trilling species. We discuss the possible properties underlying the cellular/synaptic mechanisms of the \‘novelty detector\’.

}, keywords = {ambient noise, auditory interneuron, insects, katydid, novelty detection, selective encoding}, issn = {0022-0949}, doi = {10.1242/jeb.089888}, url = {http://jeb.biologists.org/cgi/doi/10.1242/jeb.089888https://syndication.highwire.org/content/doi/10.1242/jeb.089888}, author = {Siegert, M. E. and Heiner R{\"o}mer and Hartbauer, M.} } @article {17177, title = {Position-dependent hearing in three species of bushcrickets (Tettigoniidae, Orthoptera)}, journal = {Royal Society Open Science}, volume = {2}, year = {2015}, month = {Oct-26-20152016}, pages = {140473}, doi = {10.1098/rsos.140473}, url = {http://rsos.royalsocietypublishing.org/lookup/doi/10.1098/rsos.140473https://syndication.highwire.org/content/doi/10.1098/rsos.140473}, author = {Lakes-Harlan, Reinhard and Scherberich, Jan} }