@article {58031, title = {Structural biomechanics determine spectral purity of bush-cricket calls}, year = {2017}, abstract = {

Bush-crickets (Orthoptera: Tettigoniidae) generate sound using tegminal stridulation. Signalling effectiveness is affected by the widely varying acoustic parameters of temporal pattern, frequency and spectral purity (tonality). During stridulation, frequency multiplication occurs as a scraper on one wing scrapes across a file of sclerotized teeth on the other. The frequency with which these tooth-scraper interactions occur, along with radiating wing cell resonant properties, dictates both frequency and tonality in the call. Bush-cricket species produce calls ranging from resonant, tonal calls through to non-resonant, broadband signals. The differences are believed to result from differences in file tooth arrangement and wing radiators, but a systematic test of the structural causes of broadband or tonal calls is lacking. Using phylogenetically controlled structural equation models, we show that parameters of file tooth density and file length are the best-fitting predictors of tonality across 40 bush-cricket species. Features of file morphology constrain the production of spectrally pure signals, but systematic distribution of teeth alone does not explain pure-tone sound production in this family.

}, keywords = {broadband, Entropy, Orthoptera, path analysis, pure-tone, stridulation}, doi = {10.1098/rsbl.2017.0573}, url = {https://royalsocietypublishing.org/doi/10.1098/rsbl.2017.0573https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2017.0573}, author = {Benedict D. Chivers and Jonsson, Thorin and Soulsbury, Carl D. and Montealegre-Z, Fernando} } @conference {57991, title = {Sound reception and radiation in a small insect}, booktitle = {Acoustics 2012}, year = {2012}, address = {Nantes, France}, abstract = {

Insects are small; this is a fact of their life. In some contexts this is an advantage, such as insects do not injure themselves through the effects of gravity. In other contexts this is a disadvantage, especially in the context of sound production and reception. The wavelengths of sound that insects such as crickets produce and receive are several times larger than their body size. For sound production, this is particularly challenging and inefficient, as sub-wavelength radiation (size to lambda ratio\ \>\ 1:100) requires great energy expenditure to produce sufficient sound pressure. In receiving sound, they face the reciprocal problem and are inefficient receivers. In addition,\  because of their size they cannot rely on cues other animals use to detect the direction of sound. Nonetheless, sound is extremely important to these insects as they use it for mate attraction and to evade predators. We investigate this problem by combining the technique of microscanning laser Doppler vibrometry with finite element modelling; and explain some of the biomechanical tricks a tiny tree cricket uses to overcome the disadvantages of size.

}, author = {Mhatre, Natasha and Montealegre-Z, Fernando and Rohini Balakrishnan and Daniel Robert} } @article {52680, title = {The spider-like katydid Arachnoscelis (Orthoptera: Tettigoniidae: Listroscelidinae): anatomical study of the genus}, journal = {Zootaxa}, volume = {3666}, year = {2013}, month = {Apr-06-2013}, pages = {591}, abstract = {

This paper provides some observations on the anatomy of the neotropical katydid Arachnoscelis arachnoides Karny (In- secta: Orthoptera: Tettigoniidae). Arachnoscelis is a genus of predaceous katydids that comprise species that resemble spi- ders in their general body appearance. The type species, A. arachnoids, was described in 1891 from a single male collected in Colombia. Following the original description, these creatures were never found again, and were thought to have gone extinct or mistakenly assigned to the type locality. But between 1891 and 2012 four more species were described and in- correctly assigned to Arachnoscelis based on a similarity of body form. In this paper we present an anatomical comparai- son of Arachnoscelis and its relatives, and propose that Arachnoscelis should be treated as a monotypic genus. This implies that other species previously described in Arachnoscelis, should be placed in different genera.

}, keywords = {bushcricket, Colombia, predator, stridulation, ultrasound}, issn = {1175-5326}, doi = {10.11646/zootaxa.3666.410.11646/zootaxa.3666.4.11}, url = {http://biotaxa.org/Zootaxa/issue/view/zootaxa.3666.4}, author = {Montealegre-Z, Fernando and Cadena-Castaneda, Oscar J. and Benedict D. Chivers} } @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 {51475, title = {Wing resonances in a new dead-leaf-mimic katydid (Tettigoniidae: Pterochrozinae) from the Andean cloud forests}, journal = {Zoologischer Anzeiger - A Journal of Comparative Zoology}, volume = {270}, year = {2017}, month = {Jan-09-2017}, pages = {60 - 70}, abstract = {

Day-camouflaged leaf-mimic katydids Typophyllum spp. have a remarkable way of evading predators as male and female forewings appear as bite-damaged leaves complete with necrotic spots. As in all other katydids, males produce sound signals to attract females by rubbing their forewings together. The biophysical properties of these special leaf-like forewings remain obscure. Here we study the wing mechanics and resonances of Typophyllum spurioculis, a new species of leaf-mimic katydid with a broad distribution in the Andes from Western Ecuador to the middle Central Cordillera in Colombia. This species performs an unusual laterally directed aposematic display, showing orange spots that simulate eyes at the leg base. At night, males are conspicuous by their loud, audible calling songs, which exhibit two spectral peaks at ca. 7 and 12 kHz. Using micro-scanning laser Doppler vibrometry we find the effective sound radiators of the wings (speculae) vibrate with three modes of vibration, two of which include the frequencies observed in the calling song. Remarkably, this resonance is preserved in the parts of the wings mimicking necrotic leaves, which are in theory not specialised for sound production. The eyespot function is discussed.

}, keywords = {bush-cricket, katydid, mimetism, resonance, stridulation}, issn = {00445231}, doi = {10.1016/j.jcz.2017.10.001}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0044523117300748}, author = {Baker, Andrew and Sarria-S, Fabio A. and Glenn K. Morris and Jonsson, Thorin and Montealegre-Z, Fernando} }