Biology subjects

Montealegre-Z, F.

Publications and source records attributed to Montealegre-Z, F..

5 recordsLinked to original sources

bioRxiv2025

Comparative analysis of morphological and acoustic correlates of bush-cricket tympanic membranes

Bush-crickets exhibit remarkable auditory diversity, having the ears in the forelegs, where the tympana could be exposed or covered by cuticular flaps known as auditory pinnae. These tympanic membranes receive sound either directly or internally via an acoustic tracheal tube. Despite extensive research on auditory tuning, the relationships between tympanal structure, body size, and acoustic traits remain unclear. In this study, {micro}CT reconstructions with AI-assisted segmentation and phylogenetically informed regressions across 18 bush-cricket species were used to investigate how tympanal surface area and mean cross-sectional thickness relate to body size, carrier frequency, and the presence of auditory pinnae. Tympanal surface area scaled positively with body size, whereas thickness was independent of size. Carrier frequency decreased with increasing body size but showed no direct association with tympanal properties. Among 14 species with auditory pinnae, tympanal dimensions showed no correlation with peak cavity resonance frequency, indicating semi-independent evolution of pinna cavity and tympanal traits. Across species, pinnae did not alter tympanal surface area, although unilateral pinnae were linked to thicker tympana. Within these unilateral species, the pinna-covered tympanum remained consistently larger in area but thinner than the exposed side. Overall, these findings indicate that tympanal evolution reflects a balance of scaling constraints and localised effects of auditory pinnae. Summary StatementThe tympanal morphology in bush-crickets reflects a balance of scaling and pinna effects. Surface area scales with body size and unilateral pinnae generate consistent asymmetries.

biophysics↗

bioRxiv2025

First high-fidelity scaled 3D-printed models of insect tympanic membrane and acoustic trachea preserving their acoustic function

Miniature dual-input hearing in katydids underpins communication and bat evasion, yet its microscale anatomy hinders acoustic studies. With {micro}CT imaging, AI-assisted segmentation and multi-material 3D printed assembly, scaled copies of high-fidelity pinna-tympanum assembly and a complete acoustic trachea of the neotropical katydid Copiphora gorgonensis were fabricated. Flexible TPU membranes reproduce similar tympanal vibrations compared to actual insect and pairing with rigid PLA pinnae mimicked the outer-ear motion, providing ultrasonic gain at 70-110 kHz matching in vivo bat-detection bands. Separately, the pressure mapping of the scaled acoustic trachea confirms the spiracle as a spectral filter and the exponential canal as a 17-21 dB amplifier, in line with simulations, preserving the 1.3 cycle phase shift seen at 23 kHz in living insects. These matching results justify the use of scaled biomimicking replicas as reusable, 3Rs-aligned substitutes for living insect acoustic studies in search bioinspired applications.

biophysics↗

bioRxiv2023

Effects of age and noise on tympanal displacement in the Desert Locust.

Insect cuticle is an evolutionary-malleable exoskeleton that has specialised for various functions. Insects that detect the pressure component of sound bear specialised sound-capturing tympani evolved from cuticular thinning. Whilst the outer layer of insect cuticle is composed of non-living chitin, its mechanical properties change during development and aging. Here, we measured the displacements of the tympanum of the desert Locust, Schistocerca gregaria, to understand biomechanical changes as a function of age and noise-exposure. We found that the stiffness of the tympanum decreases within 12 hours of noise-exposure and increases as a function of age, independent of noise-exposure. Noise-induced changes were dynamic with an increased tympanum displacement to sound within 12 hours post noise-exposure. Within 24 hours, however, the tone-evoked displacement of the tympanum decreased below that of control Locusts. After 48 hours, the tone-evoked displacement of the tympanum was not significantly different to Locusts not exposed to noise. Tympanal displacements reduced predictably with age and repeatably noise-exposed Locusts (every three days) did not differ from their non-noise-exposed counterparts. Changes in the biomechanics of the tympanum may explain an age-dependent decrease in auditory detection in tympanal insects.

biophysics↗

bioRxiv2021

The ultrasound guide: katydid ear pinnae code for bat call detection

Early predator detection is a key component of the predator-prey arms race, and has driven the evolution of multiple animal hearing systems. Katydids (Insecta) have sophisticated ears, each consisting of paired tympana on each foreleg that receive sound directly externally, and internally via a narrowing ear canal through the acoustic spiracle. These ears are pressure-time difference receivers capable of sensitive and accurate directional hearing across a wide frequency range, despite the small size of katydids. Many katydid species have cuticular pinnae which form cavities around the outer tympanal surfaces, but their function is unknown. We investigated pinnal function in the katydid Copiphora gorgonensis by combining experimental biophysics and numerical modelling using 3D ear geometries. Results show that the pinnae in C. gorgonensis do not assist in directional hearing for specific call frequencies, but instead pinnae act as ultrasound detector devices. Pinnae induced large sound pressure gains that enhanced sound detection at high ultrasonic frequencies (> 60 kHz), matching the echolocation range of co-occurring insectivorous bats. Comparing pinnal mechanics of sympatric katydid species supports these findings, and suggests that pinnae evolved in katydids primarily for enhanced predator detection. Audiograms (both behavioural and neural) and tympanal cavity resonances obtained from living specimens corroborate our findings.

biophysics↗

bioRxiv2019

Recording of \"sonic attacks\" on U.S. diplomats in Cuba spectrally matches the echoing call of a Caribbean cricket

Beginning in late 2016, diplomats posted to the United States embassy in Cuba began to experience unexplained health problems--including ear pain, tinnitus, vertigo, and cognitive difficulties1-4--which reportedly began after they heard1,2 strange noises in their homes or hotel rooms. In response, the U.S. government dramatically reduced1-3 the number of diplomats posted at the U.S. embassy in Havana. U.S. officials initially believed1,2,5 a sonic attack might be responsible for their ailments. The sound linked to these attacks, which has been described as a \"high-pitched beam of sound\", was recorded by U.S. personnel in Cuba and released by the Associated Press (AP). Because these recordings are the only available non-medical evidence of the sonic attacks, much attention has focused on identifying health problems6-11 and the origin12-17 of the acoustic signal. As shown here, the calling song of the Indies short-tailed cricket (Anurogryllus celerinictus) matches, in nuanced detail, the AP recording in duration, pulse repetition rate, power spectrum, pulse rate stability, and oscillations per pulse. The AP recording also exhibits frequency decay in individual pulses, a distinct acoustic signature of cricket sound production. While the temporal pulse structure in the recording is unlike any natural insect source, when the cricket call is played on a loudspeaker and recorded indoors, the interaction of reflected sound pulses yields a sound virtually indistinguishable from the AP sample. This provides strong evidence that an echoing cricket call, rather than a sonic attack or other technological device, is responsible for the sound in the released recording. Although the causes of the health problems reported by embassy personnel are beyond the scope of this paper, our findings highlight the need for more rigorous research into the source of these ailments, including the potential psychogenic effects, as well as possible physiological explanations unrelated to sonic attacks.

biophysics↗