01941nas a2200205 4500008004100000245007600041210006900117520123000186653001401416653001201430653001501442653001801457653001401475653001701489100002601506700002001532700002401552700002801576856013101604 2017 eng d00aStructural biomechanics determine spectral purity of bush-cricket calls0 aStructural biomechanics determine spectral purity of bushcricket3 a

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.

10abroadband10aEntropy10aOrthoptera10apath analysis10apure-tone10astridulation1 aChivers, Benedict, D.1 aJonsson, Thorin1 aSoulsbury, Carl, D.1 aMontealegre-Z, Fernando uhttps://royalsocietypublishing.org/doi/10.1098/rsbl.2017.0573https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2017.057302113nas a2200145 4500008004100000245013500041210006900176260001600245520156700261100003301828700001901861700002001880700002401900856004301924 2017 eng d00aMorphological determinants of carrier frequency signal in katydids (Orthoptera): a comparative analysis using biophysical evidence0 aMorphological determinants of carrier frequency signal in katydi cApr-09-20183 a

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).

1 aMontealegre-Zapata, Fernando1 aOgden, Jessica1 aJonsson, Thorin1 aSoulsbury, Carl, D. uhttp://doi.wiley.com/10.1111/jeb.1317902036nas a2200157 4500008004100000245008500041210006900126260001600195300001200211490000600223520143000229100002401659700002401683700003301707856013801740 2017 eng d00aNon-invasive biophysical measurement of travelling waves in the insect inner ear0 aNoninvasive biophysical measurement of travelling waves in the i cJul-18-2017 a170-1710 v43 a

Frequency analysis in the mammalian cochlea depends on the propagation of frequency information in the form of a travelling wave (TW) across tonotopically arranged auditory sensilla. TWs have been directly observed in the basilar papilla of birds and the ears of bush-crickets (Insecta: Orthoptera) and have also been indirectly inferred in the hearing organs of some reptiles and frogs. Existing experimental approaches to measure TW function in tetrapods and bush-crickets are inherently invasive, compromising the fine-scale mechanics of each system. Located in the forelegs, the bush-cricket ear exhibits outer, middle and inner components; the inner ear containing tonotopically arranged auditory sensilla within a fluid-filled cavity, and externally protected by the leg cuticle. Here, we report bush-crickets with transparent ear cuticles as potential model species for direct, non-invasive measuring of TWs and tonotopy. Using laser Doppler vibrometry and spectroscopy, we show that increased transmittance of light through the ear cuticle allows for effective non-invasive measurements of TWs and frequency mapping. More transparent cuticles allow several properties of TWs to be precisely recovered and measured in vivo from intact specimens. Our approach provides an innovative, non-invasive alternative to measure the natural motion of the sensilla-bearing surface embedded in the intact inner ear fluid.

1 aSarria-S, Fabio, A.1 aSoulsbury, Carl, D.1 aMontealegre-Zapata, Fernando uhttp://rsos.royalsocietypublishing.org/lookup/doi/10.1098/rsos.170171https://syndication.highwire.org/content/doi/10.1098/rsos.170171