@article {52657, title = {Vocalization in caterpillars: a novel sound-producing mechanism for insects}, journal = {The Journal of Experimental Biology}, volume = {221}, year = {2018}, month = {May-20-20182236}, pages = {jeb169466}, abstract = {

Insects have evolved a great diversity of sound-producing mechanisms largely attributable to their hardened exoskeleton, which can be rubbed, vibrated or tapped against different substrates to produce acoustic signals. However, sound production by forced air, while common in vertebrates, is poorly understood in insects. We report on a caterpillar that \‘vocalizes\’ by forcing air into and out of its gut. When disturbed, larvae of the Nessus sphinx hawkmoth (Sphingidae: Amphion floridensis) produce sound trains comprising a stereotyped pattern of long (370 ms) followed by multiple short-duration (23 ms) units. Sounds are emitted from the oral cavity, as confirmed by close-up videos and comparing sound amplitudes at different body regions. Numerical models using measurements of the caterpillar foregut were constructed to test hypotheses explaining sound production. We propose that sound is generated by ring vortices created as air flows through the orifice between two foregut chambers (crop and oesophagus), a mechanism analogous to a whistling kettle. As air flows past the orifice, certain sound frequencies are amplified by a Helmholtz resonator effect of the oesophagus chamber. Long sound units occur during inflation, while short sound units occur during deflation. Several other insects have been reported to produce sounds by forced air, but the aeroacoustic mechanisms of such sounds remain elusive. Our results provide evidence for this mechanism by showing that caterpillars employ mechanisms similar to rocket engines to produce sounds.

}, keywords = {acoustics, Amphion floridensis, defence, Forced air, Helmholtz resonators, Pulsating jet flows}, issn = {0022-0949}, doi = {10.1242/jeb.169466}, url = {http://jeb.biologists.org/lookup/doi/10.1242/jeb.169466https://syndication.highwire.org/content/doi/10.1242/jeb.169466https://syndication.highwire.org/content/doi/10.1242/jeb.169466}, author = {Rosi-Denadai, Conrado A. and Scallion, Melanie L. and Merrett, Craig G. and Yack, Jayne E.} } @article {40433, title = {Sound production in primitive Orthoptera from Western Australia: sounds used in defence and social communication in Ametrus sp. and Hadrogryllacris sp. (Gryllacrididae: Orthoptera)}, journal = {Journal of Natural History}, volume = {31}, year = {1997}, month = {Jan-07-1997}, pages = {1127 - 1141}, abstract = {

Sound production in two undescribed species of Gryllacrididae belonging to the genus Ametrus sp. and Hadrogryllacris sp. takes the form of defensive stridulation and intra-specific signalling by drumming on the substrate. Defensive stridulation is produced as part of an elaborate visual display, by femoro-tergal stridulation. Two rows of spines on abdominal tergites II and III of both species are rubbed by an elongate area of tubercules on the inner femoral surface of the hind legs. Analysis showed that the motion of the leg relative to the abdomen involves a complex counter-rotation of the leg between leg and abdomen. The defensive display may be performed in day light. Social signalling in both species occurs after dark, and involves drumming on the substrate by both hind legs in loose synchrony. Drumming is rhythmic and species\&$\#$39; specific. Males respond to playback calls and females duet with males. The evolution of this calling behaviour is discussed and comparisons are made with the other primitive ensiferan family known to produce both tergo-abdominal defensive stridulation and femoral drumming behaviour, the Stenopelmatidae.

}, keywords = {defence, duetting, social communication, sound production, substrate vibration}, issn = {0022-2933}, doi = {10.1080/00222939700770591}, url = {http://www.tandfonline.com/doi/abs/10.1080/00222939700770591}, author = {Field, L.H. and Winston J. Bailey} }