Generation of extreme ultrasonics in rainforest katydids

Abstract

129·kHz (the highest calling note produced by an Arthropod). Paradoxically, these extremely highfrequency sound waves are produced by a low-velocity movement of the stridulatory forewings. Sound production during a wing stroke is pulsed, but the wings do not pause in their closing, requiring that the scraper, in its travel along the file, must do so to create the pulses. We hypothesize that during scraper pauses, the cuticle behind the scraper is bent by the ongoing relative displacement of the wings, storing deformation energy. When the scraper slips free it unbends while being carried along the file and its deformation energy contributes to a more powerful, higher-rate, one-tooth one-wave sound pulse, lasting no more than a few waves at 129·000·Hz. Some other katydid species make pure-tone ultrasonic pulses. Wing velocities and carriers among these pure-tone species fall into two groups: (1) species with ultrasonic carriers below 40·kHz that have higher calling frequencies correlated with higher wing-closing velocities and higher tooth densities: for these katydids the relationship between average tooth strike rate and song frequency approaches 1:1, as in cricket escapement mechanisms; (2) a group of species with ultrasonic carriers above 40·kHz (that includes the Meconematinae): for these katydids closing wing velocities are dramatically lower and they make short trains of pulses, with intervening periods of silence greater than the duration of the pulses they separate. This signal form may be the signature of scraper-stored elastic energy.

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

“…Similar to C. (Belwood, 1988(Belwood, , 1990Belwood and Morris, 1987;Morris et al, 1994;Römer et al, 2010). Eavesdropping seems to explain why some bush-crickets use such bewilderingly high principal carriers (Belwood and Morris, 1987;Falk et al, 2015;Montealegre-Z et al, 2006;Montealegre-Z et al, 2011b;Morris et al, 1994;Sarria-S et al, 2014). Several of these species using ultrasonic carriers and pure tones alternate their low-duty-cycle acoustic signals with substratum vibrations (Morris et al 1994, F. Sarria-S personal observations).…”

Lack of correlation between vertical distribution and carrier frequency, and preference for open spaces in arboreal katydids that use extreme ultrasound, in Gorgona, Colombia (Orthoptera: Tettigoniidae)

“…The use of extremely high frequencies by South American katydids suggests unknown acoustic mechanisms responsible for the acoustic energy and the tuning of these signals (Montealegre-Z, Morris & Mason, 2006). Typically, calling songs are is produced by males to attract conspecific females (Morris, 1999).…”

“…Katydids on the other hand use more diverse signals and exploit a large range of frequencies (Heller, 1988, Pierce, 1948Suga, 1966 ;Montealegre-Z, 2009). Some species produce only pure tones, some use broadband loud sounds (Morris, Mason, Wall & Belwood, 1994) and at frequencies ranging from very low, as in crickets, to extremely high ultrasonic frequencies above 100kHz (Mason & Bailey, 1998;Montealegre-Z et al, 2006;Morris et al, 1994;Römer, Spickermann & Bailey, 1998). in these species, the speed of wing movement required to move the plectrum along the file at a rate corresponding to the sound frequency is too high to be achieved by simple muscular contraction.…”

“…in these species, the speed of wing movement required to move the plectrum along the file at a rate corresponding to the sound frequency is too high to be achieved by simple muscular contraction. These species make use of a mechanism that combines muscle-driven wing movement with stored elastic energy from bending cuticular structures (Montealegre-Z et al, 2006).…”

Changing resonator geometry to boost sound power decouples size and song frequency in a small insect

“…Little is known, however, about the relationship between temperature, the stridulatory mechanism, and wing resonances in Oecathines (23,26). Even less is known about the evolutionary reasons for their remarkable wings and the consequences of having sound radiators that are so different from those of the previously studied field crickets (27,28) and katydids (29,30).…”