@article {51480, title = {Chamber music: an unusual Helmholtz resonator for song amplification in a Neotropical bush-cricket (Orthoptera, Tettigoniidae)}, journal = {The Journal of Experimental Biology}, volume = {220}, year = {2017}, month = {Sep-15-20172153}, pages = {2900 - 2907}, abstract = {

Animals use sound for communication, with high-amplitude signals being selected for attracting mates or deterring rivals. High amplitudes are attained by employing primary resonators in sound producing structures to amplify the signal (e.g., avian syrinx). Some species actively exploit acoustic properties of natural structures to enhance signal transmission by using these as secondary resonators (e.g., tree-hole frogs). Male bush-crickets produce sound by tegminal stridulation and often use specialised wing areas as primary resonators. Interestingly, Acanthacara acuta, a Neotropical bush-cricket, exhibits an unusual pronotal inflation, forming a chamber covering the wings. It has been suggested that such pronotal chambers enhance amplitude and tuning of the signal by constituting a (secondary) Helmholtz resonator. If true, the intact system \– when stimulated sympathetically with broadband sound \– should show clear resonance around the song carrier frequency which should be largely independent of pronotum material, and change when the system is destroyed. Using laser Doppler vibrometry on living and preserved specimens, micro computed tomography, 3D printed models, and finite element modelling, we show that the pronotal chamber not only functions as a Helmholtz resonator due to its intact morphology but also resonates at frequencies of the calling song on itself, making song production a three-resonator system.

}, keywords = {acoustic resonator, bioacoustics, bush-cricket, finite element modelling, laser Doppler vibrometry, micro computed tomography}, issn = {0022-0949}, doi = {10.1242/jeb.160234}, url = {http://jeb.biologists.org/lookup/doi/10.1242/jeb.160234}, author = {Jonsson, Thorin and Robson Brown, Kate and Sarria-S, Fabio A. and Walker, Matthew and Montealegre-Z, Fernando} } @article {20919, title = {Functional morphology of tegmina-based stridulation in the relict species Cyphoderris monstrosa (Orthoptera: Ensifera: Prophalangopsidae)}, journal = {The Journal of Experimental Biology}, volume = {220}, year = {2017}, month = {Dec-28-20172143}, pages = {1112 - 1121}, abstract = {

Male grigs, bush crickets and crickets produce mating calls by tegminal stridulation: the scraping together of modified forewings functioning as sound generators. Bush crickets (Tettigoniidae) and crickets (Gryllinae) diverged some 240 million years ago, with each lineage developing unique characteristics in wing morphology and the associated mechanics of stridulation. The grigs (Prophalangopsidae), a relict lineage more closely related to bush crickets than to crickets, are believed to retain plesiomorphic features of wing morphology. The wing cells widely involved in sound production, such as the harp and mirror, are comparatively small, poorly delimited and/or partially filled with cross-veins. Such morphology is similarly observed in the earliest stridulating ensiferans, for which stridulatory mechanics remains poorly understood. The grigs, therefore, are of major importance to investigate the early evolutionary stages of tegminal stridulation, a critical innovation in the evolution of the Orthoptera. The aim of this study is to appreciate the degree of specialization on grig forewings, through identification of sound radiating areas and their properties. For well-grounded comparisons, homologies in wing venation (and associated areas) of grigs and bush crickets are re-evaluated. Then, using direct evidence, this study confirms the mirror cell, in association with two other areas (termed \‘neck\’ and \‘pre-mirror\’), as the acoustic resonator in the grig Cyphoderris monstrosa. Despite the use of largely symmetrical resonators, as found in field crickets, analogous features of stridulatory mechanics are observed between C. monstrosa and bush crickets. Both morphology and function in grigs represents transitional stages between unspecialized forewings and derived conditions observed in modern species.

}, issn = {0022-0949}, doi = {10.1242/jeb.153106}, url = {http://jeb.biologists.org/lookup/doi/10.1242/jeb.153106https://syndication.highwire.org/content/doi/10.1242/jeb.153106}, author = {B{\'e}thoux, Olivier and Sarria-S, Fabio A. and Jonsson, Thorin and Mason, Andrew C. and Fernando Montealegre-Zapata} }