TY - JOUR T1 - Structural biomechanics determine spectral purity of bush-cricket calls Y1 - 2017 A1 - Benedict D. Chivers A1 - Jonsson, Thorin A1 - Soulsbury, Carl D. A1 - Montealegre-Z, Fernando KW - broadband KW - Entropy KW - Orthoptera KW - path analysis KW - pure-tone KW - stridulation AB -

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.

UR - https://royalsocietypublishing.org/doi/10.1098/rsbl.2017.0573https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2017.0573 ER - TY - JOUR T1 - Chamber music: an unusual Helmholtz resonator for song amplification in a Neotropical bush-cricket (Orthoptera, Tettigoniidae) JF - The Journal of Experimental Biology Y1 - 2017 A1 - Jonsson, Thorin A1 - Robson Brown, Kate A1 - Sarria-S, Fabio A. A1 - Walker, Matthew A1 - Montealegre-Z, Fernando KW - acoustic resonator KW - bioacoustics KW - bush-cricket KW - finite element modelling KW - laser Doppler vibrometry KW - micro computed tomography AB -

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.

VL - 220 UR - http://jeb.biologists.org/lookup/doi/10.1242/jeb.160234 IS - 16 JO - J Exp Biol ER - TY - JOUR T1 - Wing resonances in a new dead-leaf-mimic katydid (Tettigoniidae: Pterochrozinae) from the Andean cloud forests JF - Zoologischer Anzeiger - A Journal of Comparative Zoology Y1 - 2017 A1 - Baker, Andrew A1 - Sarria-S, Fabio A. A1 - Glenn K. Morris A1 - Jonsson, Thorin A1 - Montealegre-Z, Fernando KW - bush-cricket KW - katydid KW - mimetism KW - resonance KW - stridulation AB -

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.

VL - 270 UR - http://linkinghub.elsevier.com/retrieve/pii/S0044523117300748 JO - Zoologischer Anzeiger - A Journal of Comparative Zoology ER - TY - JOUR T1 - Morphological determinants of carrier frequency signal in katydids (Orthoptera): a comparative analysis using biophysical evidence JF - Journal of Evolutionary Biology Y1 - 2017 A1 - Fernando Montealegre-Zapata A1 - Ogden, Jessica A1 - Jonsson, Thorin A1 - Soulsbury, Carl D. AB -

Male katydids produce mating calls by stridulation using specialized structures on the forewings. The right wing (RW) bears a scraper connected to a drum-like cell known as the mirror and a left wing (LW) that overlaps the RW and bears a serrated vein on the ventral side, the stridulatory file. Sound is generated with the scraper sweeping across the file, producing vibrations that are amplified by the mirror. Using this sound generator, katydids exploit a range of song carrier frequencies (CF) unsurpassed by any other insect group, with species singing as low as 600 Hz and others as high as 150 kHz. Sound generator size has been shown to scale negatively with CF, but such observations derive from studies based on few species, without phylogenetic control, and/or using only the RW mirror length. We carried out a phylogenetic comparative analysis involving 94 species of katydids to study the relationship between LW and RW components of the sound generator and the CF of the male's mating call, while taking into account body size and phylogenetic relationships. The results showed that CF negatively scaled with all morphological measures, but was most strongly related to components of the sound generation system (file, LW and RW mirrors). Interestingly, the LW mirror (reduced and non-functional) predicted CF more accurately than the RW mirror, and body size is not a reliable CF predictor. Mathematical models were verified on known species for predicting CF in species for which sound is unknown (e.g. fossils or museum specimens).

UR - http://doi.wiley.com/10.1111/jeb.13179 JO - J. Evol. Biol. ER - TY - JOUR T1 - Wing mechanics, vibrational and acoustic communication in a new bush-cricket species of the genus Copiphora (Orthoptera: Tettigoniidae) from Colombia JF - Zoologischer Anzeiger - A Journal of Comparative Zoology Y1 - 2016 A1 - Sarria-S, Fabio A. A1 - Buxton, Kallum A1 - Jonsson, Thorin A1 - Fernando Montealegre-Zapata KW - bioacoustics KW - biotremology KW - bush-cricket KW - laser Doppler vibrometer KW - resonance KW - tremulation KW - ultrasound AB -

Male bush-crickets produce acoustic signals by wing stridulation to call females. Several species also alternate vibratory signals with acoustic calls for intraspecific communication, a way to reduce risk of detection by eavesdropping predators. Both modes of communication have been documented mostly in neotropical species, for example in the genus Copiphora. In this article, we studied vibratory and acoustic signals and the biophysics of wing resonance in Copiphora vigorosa, a new species from the rainforest of Colombia. Different from other Copiphora species in which the acoustic signals have been properly documented as pure tones, C. vigorosa males produce a complex modulated broadband call peaking at ca. 30 kHz. Since males of this species do rarely sing, we also report that substratum vibrations have been adopted in this species as a persistent communication channel. Wing resonances and substratum vibrations were measured using a μ-scanning Laser Doppler Vibrometry. We found that the stridulatory areas of both wings exhibit a relatively broad-frequency response and the combined vibration outputs fits with the calling song spectrum breadth. The broadband calling song spectrum results from several wing resonances activated simultaneously during stridulation. Under laboratory conditions the calling song duty cycle is very low and males spend more time tremulating than singing.

VL - 263 UR - http://linkinghub.elsevier.com/retrieve/pii/S0044523116300584 JO - Zoologischer Anzeiger - A Journal of Comparative Zoology ER - TY - JOUR T1 - Functional morphology of tegmina-based stridulation in the relict species Cyphoderris monstrosa (Orthoptera: Ensifera: Prophalangopsidae) JF - The Journal of Experimental Biology Y1 - 2017 A1 - BĂ©thoux, Olivier A1 - Sarria-S, Fabio A. A1 - Jonsson, Thorin A1 - Mason, Andrew C. A1 - Fernando Montealegre-Zapata AB -

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.

VL - 220 UR - http://jeb.biologists.org/lookup/doi/10.1242/jeb.153106https://syndication.highwire.org/content/doi/10.1242/jeb.153106 IS - 6 JO - J Exp Biol ER - TY - JOUR T1 - Ultrasonic reverse stridulation in the spider-like katydid Arachnoscelis (Orthoptera: Listrosceledinae) JF - Bioacoustics Y1 - 2014 A1 - Benedict D. Chivers A1 - Jonsson, Thorin A1 - Cadena-Castaneda, Oscar J. A1 - Fernando Montealegre-Zapata KW - biomechanics KW - Colombia KW - elastic energy KW - stridulation KW - ultrasound AB -

This paper illustrates the biomechanics of sound production in the neotropical predaceous katydid Arachnoscelis arachnoides (Insecta: Orthoptera: Tettigoniidae). Described and previously known from only one male specimen, this genus of predaceous katydids resembles spiders in their general body appearance. To call distant females, male katydids produce songs by stridulation where one forewing possessing a sclerotized file rubs against a row of teeth (scraper) on the other wing. In most katydid species, the songs are produced during the wing-closing phase of the stridulation. Morphological comparative studies of the stridulatory apparatus of the type specimen of Arachnoscelis arachnoides and males of other closely related species suggest that this insect sings with a frequency of ca. 80 kHz to attract conspecific females. We found an abundant population of A. arachnoides in Central Northeast of Colombia and undertook a complete analysis of the biomechanics of stridulation in this species. Using ultrasound-sensitive equipment and high-speed video, we determined that male A. arachnoides sing at ca. 74 kHz and use elastic energy and wing deformation to reach such ultrasonic frequencies. In contrast to most katydids, males of this species produce their calls during the opening phase of the wing; this form of stridulation is discussed.

VL - 23 UR - http://www.tandfonline.com/doi/abs/10.1080/09524622.2013.816639 IS - 1 JO - Bioacoustics ER -