Hornworm counterattacks: defensive strikes and sound production in response to invertebrate attackers

Publication Type:Journal Article
Year of Publication:2018
Authors:Sugiura, S, Takanashi, T
Journal:Biological Journal of the Linnean Society
Pagination:496 - 505
Date Published:May-18-2018

Caterpillars (i.e. lepidopteran larvae) have evolved multiple defences against predators, with some large caterpillars showing aggressive defences (e.g. strikes and/or sound production). Although such behaviours can startle or warn vertebrate predators, defences against invertebrates remain unclear. We investigated the behavioural responses of the hornworm Langia zenzeroides (Lepidoptera: Sphingidae) against the invertebrate attacker Calosoma maximowiczi (Coleoptera: Carabidae). Fifth (last) instars of L. zenzeroides exhibited a striking response, in which the larva rapidly bent its head and thorax towards the body part stimulated by C. maximowiczi attacks. Strikes were also accompanied by opening of the mandibles, followed by sound production or regurgitation. In some cases, L. zenzeroides larvae caught the legs of C. maximowiczi and threw the beetles using their mandibles. Such counterattacks completely defended against attackers. The sounds that L. zenzeroides generated (pulse durations, 82–314 ms; dominant frequencies, 5.0–8.7 kHz; sound pressure level, 44.0–56.9 dB SPL) were produced by forcing air through the eighth pair of abdominal spiracles. Our results indicate that hornworm larvae are able to deter predacious invertebrates using multiple defences.

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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith