Ear pinnae in a neotropical katydid (Orthoptera: Tettigoniidae) function as ultrasound guides for bat detection

Pulver, Christian Adlai, Celiker, Emine, Woodrow, Charlie , Geipel, Inga, Soulsbury, Carl, Cullen, Darron, Rogers, Stephen, Veitch, Daniel and Montealegre-Z, Fernando (2022) Ear pinnae in a neotropical katydid (Orthoptera: Tettigoniidae) function as ultrasound guides for bat detection. eLife, 11 . ISSN 2050-084X

Full content URL: https://doi.org/10.7554/eLife.77628

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Ear pinnae in a neotropical katydid (Orthoptera: Tettigoniidae) function as ultrasound guides for bat detection
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Abstract

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 both externally, through the air, and internally via a narrowing ear canal running through the leg from an acoustic spiracle on the thorax. These ears are pressure-time difference receivers capable of sensitive and accurate directional hearing across a wide frequency range. 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. We found that the pinnae in C. gorgonensis do not assist in directional hearing for specific call frequencies, but instead act as ultrasound detectors. Pinnae induced large sound pressure gains (20–30 dB) that enhanced sound detection at high ultrasonic frequencies (> 60 kHz), matching the echolocation range of co-occurring insectivorous bats. These findings were supported by behavioural and neural audiograms and tympanal cavity resonances from live specimens, and comparisons with the pinnal mechanics of sympatric katydid species, which together suggest that katydid pinnae primarily evolved for the enhanced detection of predatory bats.

Keywords:bushcricket, bioacoustics, ultrasound hearing, 3D printing, bat predation
Subjects:C Biological Sciences > C180 Ecology
B Subjects allied to Medicine > B140 Neuroscience
F Physical Sciences > F361 Laser Physics
C Biological Sciences > C910 Applied Biological Sciences
G Mathematical and Computer Sciences > G120 Applied Mathematics
B Subjects allied to Medicine > B120 Physiology
D Veterinary Sciences, Agriculture and related subjects > D322 Animal Physiology
Divisions:College of Science > School of Life and Environmental Sciences > Department of Life Sciences
ID Code:50624
Deposited On:09 Sep 2022 13:28

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