Wing mechanics, vibrational and acoustic communication in a new bush-cricket species of the genus Copiphora (Orthoptera: Tettigoniidae) from Colombia

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 C. 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. Such a broadband spectrum results from several wing resonances activated simultaneously during stridulation. 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. Under laboratory conditions the calling song duty cycle is very low and males spend more time tremulating than singing

Shrinking wings for ultrasonic pitch production: hyperintense ultra-short-wavelength calls in a new genus of neotropical katydids (Orthoptera: tettigoniidae)

This article reports the discovery of a new genus and three species of predaceous katydid (Insecta: Orthoptera) from Colombia and Ecuador in which males produce the highest frequency ultrasonic calling songs so far recorded from an arthropod. Male katydids sing by rubbing their wings together to attract distant females. Their song frequencies usually range from audio (5 kHz) to low ultrasonic (30 kHz). However, males of Supersonus spp. call females at 115 kHz, 125 kHz, and 150 kHz. Exceeding the human hearing range (50 Hz–20 kHz) by an order of magnitude, these insects also emit their ultrasound at unusually elevated sound pressure levels (SPL). In all three species these calls exceed 110 dB SPL rms re 20 µPa (at 15 cm). Males of Supersonus spp. have unusually reduced forewings (<0.5 mm2). Only the right wing radiates appreciable sound, the left bears the file and does not show a particular resonance. In contrast to most katydids, males of Supersonus spp. position and move their wings during sound production so that the concave aspect of the right wing, underlain by the insect dorsum, forms a contained cavity with sharp resonance. The observed high SPL at extreme carrier frequencies can be explained by wing anatomy, a resonant cavity with a membrane, and cuticle deformation

Data from: Non-invasive biophysical measurement of travelling waves in the insect inner ear

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

Supplementary Figure 3 from Non-invasive biophysical measurement of travelling waves in the insect inner ear

Cuticle transparency in a glass bush-cricket Phlugis sp. (a) Lateral view of the femur, the acoustic trachea is clearly visible through the cuticle without manipulation of the animal. (b) Dorsal view of the hearing organ. The cap cells (scolopidia) are visible through the cuticle

Supplementary Figure 1 from Non-invasive biophysical measurement of travelling waves in the insect inner ear

Examples of cuticle dissections for quantification of cuticle thickness. (a) Dorsal view of the ear, red line indicates location of cross section dissection. (b) Copiphora vigarosa. (c) Copiphora gorgonensis. (d) Phlugis poecila. (e) Acantheremus sp. (f) Nastonotus foreli

Measurements (in mm) of some morphological structures of <i>Supersonus</i> spp. F = fore, M = mid, H = hind, S = subgenital.

<p>Measurements (in mm) of some morphological structures of <i>Supersonus</i> spp. F =  fore, M =  mid, H =  hind, S =  subgenital.</p

Wing resonance in <i>S. piercei</i> as measured with Laser Doppler Vibrometry.

<p>(<b>A–D</b>) Scanned area and defection shapes of the right wing (RW). A and B show the orientation image relating wing topology to the position of the scanning latice. (<b>C</b>, <b>D</b>) Area scans of mirror deflection at best response (122 kHz in this species). Wings scanned in normal position close to the body. Note how the mirror membrane strongly deflects while the rest of the wing veins and folded membranes rest in position. (<b>E</b>) Displacement and resonances of the left wing (LW) and RW. (<b>F</b>) Phase gain response of RW vibration. (<b>G</b>) Coherence across the frequency range measured for the RW response. (<b>H</b>) Expected and observed radiator size optimal for the frequencies used by <i>Supersonus</i> spp.</p

Acoustical and biomechanical measurements of <i>Supersonus</i> spp., mean values (refer to text for standard errors).

<p>Acoustical and biomechanical measurements of <i>Supersonus</i> spp., mean values (refer to text for standard errors).</p

Male right wing morphology of <i>Supersonus piercei</i> (right side view).

<p>Male right wing morphology of <i>Supersonus piercei</i> (right side view).</p

Morphological comparision of <i>Supersonus</i> spp. habitus.

<p>(A, B) Male and female of <i>S. aequoreus</i>. (C, D) Male and female of <i>S. piercei</i>, and (E, F) Male and female of <i>S. undulus</i>. (A) Under a CC BY license, with permission from Natasha Mhatre, original copyright 2010. (C, D) Under a CC BY license, with permission from Manuel Jara, original copyright 2014. (B, E, F) Under a CC BY license, with permission from Fernando Vargas-Salinas, original copyright 2011.</p