02488nas a2200253   4500008004100000022001400041245008000055210006900135260002000204300001400224490000800238520158900246653001401835653002401849653001201873653001501885653002501900653002401925100003001949700002601979700002302005700002002028856018602048       2018                        eng d  a0022-094900aVocalization in caterpillars: a novel sound-producing mechanism for insects0 aVocalization in caterpillars a novel soundproducing mechanism fo  cMay-20-20182236  ajeb1694660 v2213 a<p>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 &lsquo;vocalizes&rsquo; 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.</p>
10aacoustics10aAmphion floridensis10adefence10aForced air10aHelmholtz resonators10aPulsating jet flows1 aRosi-Denadai, Conrado, A.1 aScallion, Melanie, L.1 aMerrett, Craig, G.1 aYack, Jayne, E.  uhttp://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