Ultrasonic reverse stridulation in the spider-like katydid Arachnoscelis (Orthoptera: Listrosceledinae)

Abstract

This paper illustrates the biomechanics of sound production in the neotropical predaceous katydid Arachnoscelis arachnoides (Insecta: Orthoptera: Tettigoniidae). Described and previously known from only one male specimen, this genus of predaceous katydids resembles spiders in their general body appearance. To call distant females, male katydids produce songs by stridulation where one forewing possessing a sclerotized file rubs against a row of teeth (scraper) on the other wing. In most katydid species, the songs are produced during the wing-closing phase of the stridulation. Morphological comparative studies of the stridulatory apparatus of the type specimen of Arachnoscelis arachnoides and males of other closely related species suggest that this insect sings with a frequency of ca. 80 kHz to attract conspecific females. We found an abundant population of A. arachnoides in Central Northeast of Colombia and undertook a complete analysis of the biomechanics of stridulation in this species. Using ultrasound-sensitive equipment and high-speed video, we determined that male A. arachnoides sing at ca. 74 kHz and use elastic energy and wing deformation to reach such ultrasonic frequencies. In contrast to most katydids, males of this species produce their calls during the opening phase of the wing; this form of stridulation is discussed.

Keywords::

• ultrasound
• elastic energy
• Colombia
• stridulation
• biomechanics

Acknowledgements

This work was in part funded by the Human Frontiers Science Programme (Cross Disciplinary Fellowship LT00024/2008-C to FM-Z). We also thank the School of Life Science, University of Lincoln for logistic support. Thanks also to Michael Shaw for technical assistant and guide using the Scanning Electron Microscope at Lincoln. We thank Prof. Daniel Robert (University of Bristol) for letting us use his equipment and Dr Oliver Bethoux (MNHN, Paris) for confirming the identification of wing veins.

Notes

^1. These authors contributed equally to this paper.