Tenors Not Sopranos: Bio-Mechanical Constraints on Calling Song Frequencies in the Mediterranean Field-Cricket

Male crickets and their close relatives bush-crickets (Gryllidae Tettigoniidae, respectively; Orthoptera Ensifera) attract distant females by producing loud calling songs. In both families, sound is produced stridulation, the rubbing together of forewings, whereby plectrum one wing rapidly passed over a serrated file on opposite wing. The resulting oscillations are amplified resonating regions. A striking difference between Gryllids Tettigoniids lies in morphology composition song frequency: Crickets produce mostly low-frequency (2–8 kHz), pure tone signals with highly bilaterally symmetric wings, while use asymmetric wings for high-frequency (10–150 kHz) calls. evolutionary reasons this acoustic divergence unknown. Here, we study actively stridulating male field-crickets ( Gryllus bimaculatus ) present vibro-acoustic data suggesting biophysical restriction to song. Using laser Doppler vibrometry (LDV) brain-injections neuroactivator eserine elicit singing, recorded topography vibrations during active production. freely vibrating each region resonated differently. When coupled these differences vanished all regions at an identical frequency, that narrow-band (∼5 kHz). However, imperfections wing-coupling caused phase shifts resonators, introducing destructive interference increasing differences. effect (amplitude reduction) was observed be minimal typical low frequency calls crickets, maintaining vibration below 80°. We show that, imperfect coupling observed, cricket production two resonators becomes acoustically inefficient above ∼8 kHz. This evidence reveals bio-mechanical constraint whilst using provides explanation as why unlike bush-crickets, have not evolved exploit ultrasonic