TY - JOUR T1 - Sound-induced tympanal membrane motion in bushcrickets and its relationship to sensory output Y1 - 2011 A1 - Hummel, J. A1 - Kossl, M. A1 - Nowotny, M. KW - insect hearing KW - katydid KW - laser-Doppler vibrometer KW - Mecopoda elongata KW - spiracle KW - tympanal nerve AB -

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.

UR - http://jeb.biologists.org/cgi/doi/10.1242/jeb.054445 ER - TY - JOUR T1 - Low-pass filters and differential tympanal tuning in a paleotropical bushcricket with an unusually low frequency call Y1 - 2013 A1 - Rajaraman, K. A1 - Mhatre, N. A1 - Jain, M. A1 - Postles, M. A1 - Rohini Balakrishnan A1 - Daniel Robert KW - auditory KW - katydid KW - laser vibrometry KW - Onomarchus uninotatus KW - Orthoptera KW - pseudophylline KW - tettigoniid KW - trachea KW - tympanum AB -

Low-frequency sounds are advantageous for long-range acoustic signal transmission, but for small animals they constitute a challenge for signal detection and localization. The efficient detection of sound in insects is enhanced by mechanical resonance either in the tracheal or tympanal system before subsequent neuronal amplification. Making small structures resonant at low sound frequencies poses challenges for insects and has not been adequately studied. Similarly, detecting the direction of long-wavelength sound using interaural signal amplitude and/or phase differences is difficult for small animals. Pseudophylline bushcrickets predominantly call at high, often ultrasonic frequencies, but a few paleotropical species use lower frequencies. We investigated the mechanical frequency tuning of the tympana of one such species, Onomarchus uninotatus, a large bushcricket that produces a narrow bandwidth call at an unusually low carrier frequency of 3.2 kHz. Onomarchus uninotatus, like most bushcrickets, has two large tympanal membranes on each fore-tibia. We found that both these membranes vibrate like hinged flaps anchored at the dorsal wall and do not show higher modes of vibration in the frequency range investigated (1.5–20 kHz). The anterior tympanal membrane acts as a low-pass filter, attenuating sounds at frequencies above 3.5 kHz, in contrast to the high-pass filter characteristic of other bushcricket tympana. Responses to higher frequencies are partitioned to the posterior tympanal membrane, which shows maximal sensitivity at several broad frequency ranges, peaking at 3.1, 7.4 and 14.4 kHz. This partitioning between the two tympanal membranes constitutes an unusual feature of peripheral auditory processing in insects. The complex tracheal shape of O. uninotatus also deviates from the known tube or horn shapes associated with simple band-pass or high-pass amplification of tracheal input to the tympana. Interestingly, while the anterior tympanal membrane shows directional sensitivity at conspecific call frequencies, the posterior tympanal membrane is not directional at conspecific frequencies and instead shows directionality at higher frequencies.

UR - http://jeb.biologists.org/cgi/doi/10.1242/jeb.078352https://syndication.highwire.org/content/doi/10.1242/jeb.078352 ER - TY - JOUR T1 - Discovery of an acoustically locating parasitoid with a potential role in divergence of song types among sympatric populations of the bush cricket Mecopoda elongata Y1 - 2019 A1 - Dutta, Rochishnu A1 - Reddy, Manjunatha A1 - Tregenza, Tom KW - cryptic species KW - katydid KW - speciation KW - Tachinidae AB -

The bush cricket Mecopoda elongata provides a striking example of sympatric intraspecific divergence in mating signals. Five completely dis- tinct song types are found in various parapatric and sympatric locations in South India. While there is convincing evidence that population diver- gence in M. elongata is being maintained as a result of divergence in acous- tic signals, cuticular chemical profiles, and genital characters, the causes of the evolution of such divergence in the first place are unknown. We describe the discovery of a tachinid parasitoid with an orthopteroid hear- ing mechanism affecting M. elongata. This parasitoid may have a role in driving the extraordinary divergence that had occurred among M. elongata song types. Over two years we sampled individuals of three sympatric song types in the wild and retained individuals in captivity to reveal rates of parasitization. We found that all three song types were infected with the parasitoid but that there were significant differences among song types in their probability of being infected. The probability of tachinid parasitiza- tion also differed between the two sampling periods. Therefore, it is pos- sible that parasitoid infection plays a role in song type divergence among sympatric bush cricket populations.

UR - https://jor.pensoft.net/article/34115/ ER - TY - JOUR T1 - Synonymies of Wasp-Mimicking Species within the Katydid Genus Aganacris (Orthoptera: Tettigoniidae: Phaneropterinae) JF - Journal of Orthoptera Research Y1 - 2012 A1 - Nickle, David A. KW - katydid KW - mimicry KW - Pompilidae KW - Sphecidae AB -

Five neotropical wasp-mimicking species of the genus Aganacris—two known only from females and three from males—are reviewed. Based on observation of interspecific interactions and morphological comparison, it is shown that sexual dimorphism occurs within species, and that female species are conspecific with sympatric male species. This is reinforced by field observations in northern Peru of a pairing between A. pseudosphex and A. nitida, wherein the male was in the process of secreting a spermatophore. Aganacris sphex and A. pseudosphex are morphologically nearly identical and probably represent variants of a single species. Since those species known from females only are both senior to sympatric male species, the number of species is reduced from five to two – A. nitida (A. pseudosphex and A. sphex designated herein as junior synonyms) and A. velutina (A. insectivora designated herein as a junior synonym).

VL - 21 UR - http://www.bioone.org/doi/abs/10.1665/034.021.0209 IS - 2 JO - Journal of Orthoptera Research ER - TY - JOUR T1 - High-speed duetting – latency times of the female acoustic response within the bush-cricket genera Leptophyes and Andreiniimon (Orthoptera, Phaneropteridae) JF - ZooKeys Y1 - 2018 A1 - Klaus-Gerhard Heller A1 - Olga S. Korsunovskaya A1 - Massa, Bruno A1 - Ionuț Ștefan Iorgu KW - duet KW - female acoustic signals KW - katydid KW - Phaneropterinae KW - stridulatory movement AB -

To find a mate, male and female bush-crickets of the family Phaneropteridae typically engage in duets. The male sings and the female responds. For mutual recognition, the amplitude pattern of the male song and the species-specific timing of the female response have been shown to be very important. In the seven studied species, belonging to the genera Leptophyes and Andreiniimon, these duets are extremely fast and nearly completely in the ultrasonic range. The females produce very short sounds by fast closing movements of the tegmina. They respond with species-specific delays of 20 to 150 ms after the beginning of the male song. The different latency times are probably not important for species recognition, since in sympatric species they are quite similar.

VL - 750 UR - https://zookeys.pensoft.net/articles.php?id=23874 JO - ZK 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 - Acoustic and Molecular Differentiation between Macropters and Brachypters of Eobiana engelhardti engelhardti (Orthoptera: Tettigonioidea) JF - Zoological Studies Y1 - 2011 A1 - Yinliang Wang A1 - Jian Zhang A1 - Xiao-Qiang Li A1 - Bing-Zhong Ren KW - insect songs KW - katydid KW - toothed files KW - wing dimorphism AB - This study focused on the wing dimorphism of Eobiana engelhardti engelhardti (Uvarov 1926). To examine acoustic differences between macropters and brachypters, we recorded and analyzed the calling songs of the 2 forms. Moreover, the vocal organs of E. e. engelhardti were also observed under optical and scanning electric microscopy. As a result, there were 3 “dynamic” song traits which had signi cant differences between the 2 forms, but no obvious differences were observed in vocal organs. For macropters, we assumed that differentiation of these calling songs showed compensation for a reproductive disadvantage. Finally, some molecular biology experiments were conducted to examine differences between the 2 forms at the molecular biology level; as a result, brachypterous insects were grouped in a clade, while macropterous insects were grouped into another, which indicates that these molecular differences had already occurred before these macropters migrated. VL - 50 IS - 5 ER - TY - JOUR T1 - Maintaining acoustic communication at a cocktail party: heterospecific masking noise improves signal detection through frequency separation JF - Journal of Experimental Biology Y1 - 2013 A1 - Siegert, M. E. A1 - Heiner Römer A1 - Hartbauer, M. KW - ambient noise KW - auditory interneuron KW - insects KW - katydid KW - novelty detection KW - selective encoding AB -

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’.

VL - 216 UR - http://jeb.biologists.org/cgi/doi/10.1242/jeb.089888https://syndication.highwire.org/content/doi/10.1242/jeb.089888 IS - 24 JO - Journal of Experimental Biology ER - TY - JOUR T1 - Panoploscelis specularis (Orthoptera: Tettigoniidae: Pseudophyllinae): extraordinary female sound generator, male description, male protest and calling signals JF - Journal of Orthoptera Research Y1 - 2003 A1 - Fernando Montealegre-Zapata A1 - Guerra, Patrick A. A1 - Glenn K. Morris KW - acoustics KW - Colombia KW - defense KW - Ecuador KW - katydid KW - stridulation AB -

Females of Panoploscelis specularis present a dramatic modification of their forewings for stridulation. The female generator is illustrated and its distinct form contrasted with that of males. The physical form of the signals that females might produce is inferred; male calling and protest signals are characterized. The male of P. specularis is described for the first time.

VL - 12 UR - http://www.bioone.org/doi/abs/10.1665/1082-6467%282003%29012%5B0173%3APSOTPE%5D2.0.CO%3B2 IS - 2 JO - Journal of Orthoptera Research ER -