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Psyche
Volume 2009 (2009), Article ID 631030, 8 pages
http://dx.doi.org/10.1155/2009/631030
Research Article

Functional Morphology of Secretion by the Large Wax Glands (Sensilla Sagittiformia) Involved in Tick Defense

1Department of Biology, Wittenberg University, Springfield, OH 45501, USA
2Department of Entomology, The Ohio State University, Columbus, OH 43210, USA

Received 10 March 2009; Accepted 4 June 2009

Academic Editor: D. Bruce Conn

Copyright © 2009 Jay A. Yoder et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ticks are protected against ants by release of an allomonal defense secretion from the large wax glands (or type 2 glands) that line their bodies. To explore how the large wax glands operate, before and after microscopic observations of these glands (nonsecreted versus secreted test groups), mass determinations were made for Rhipicephalus sanguineus that had been exhausted of secretion by repeated leg pinching to simulate attack by a predator. Prior to secretion, the glandular organ is fully intact histologically and matches the sensillum sagittiforme, a key taxonomic structure described in the 1940s. The large wax gland is innervated and responds to pressure stimulation as a proprioceptor that stimulates the secretory response. Histological observations after secretion has occurred show that the entire glandular contents and associated cells are jettisoned out of the gland like a syringe. The glandular cellular components are subsequently rebuilt by underlying hypodermal cells within a few days so that secretion can take place again. Presumably, the active allomonal ingredients (hydrocarbons) are released when these derived epidermal cells reach and burst onto the cuticular surface. Our conclusion is that the large wax glands are holocrine and feature intermittent regeneration.