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Abstract

Male Katydids (Orthoptera: Tettigoniidae) rub together their specialised forewings to produce sound, a process
known as stridulation. During wing closure, a lobe on the anal margin of the right forewing (a scraper), engages
with a teeth-covered file on the left forewing. The movement of the scraper across the file produces vibrations
which are amplified by a large wing cell adjacent to the scraper, the mirror. Katydids are known to stridulate
with either sustained or interrupted sweeps of the file, generating resonant pure-tone (narrowband frequency)
or non-resonant (broadband frequencies) calls. However, some species can conserve some purity in their calls
despite incorporating discrete pulses and silent intervals. This mechanism is exhibited by many Pseudophyllinae,
such as Nastonotus spp., Cocconotus spp., Triencentrus spp. and Eubliastes spp. This study aims to measure and
quantify the mechanics of wing stridulation in Nastonotus foreli, a Neotropical katydid that can produce complex,
relatively narrowband calls at ≈20kHz. It was predicted that this species will use a stridulatory mechanism
involving elastic energy whereby the scraper bends and flicks along the file in periodic bursts. The calling behaviour
and wing mechanics of seven males were studied using a combination of technologies (e.g. micro-scanning
laser Doppler vibrometry, advanced microscopy, ultrasound-sensitive equipment and optical motion detectors)
to quantify wing mechanics and structure. Analysis of recordings revealed no clear relationship between wing
velocity and carrier frequency, and a pronounced distinction between wing velocity and scraper velocity during
wing closure, suggesting that the scraper experiences considerable deformation. This is characteristic of the elastic
scraper mechanism of stridulation. Curiously, N. foreli might have evolved to employ elastic energy to double
the duration of the call, despite possessing muscles that can reach velocities high enough to produce the same
frequency without the help of elastic energy.

Available Versions of this Item

• Complex wing motion during stridulation in the katydid Nastonotus foreli (Orthoptera: Tettigoniidae: Pseudophyllinae). (deposited 11 Apr 2019 13:22)
  • Complex wing motion during stridulation in the katydid Nastonotus foreli (Orthoptera: Tettigoniidae: Pseudophyllinae). (deposited 11 Apr 2019 13:26) [Currently Displayed]