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First published online October 7, 2005
Journal of Experimental Biology 208, 3925-3931 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01861
The role of UV in crab spider signals: effects on perception by prey and predators
1 Department of Biological Sciences, Macquarie University, North Ryde, 2109
NSW Australia
2 Centre for the Integrative Study of Animal Behaviour, Macquarie
University, North Ryde, 2109 NSW Australia
3 School of Biological Sciences, Queen Mary College, University of London,
Mile End Road, London E1 4NS, UK
* Author for correspondence (e-mail: astrid.heiling{at}univie.ac.at)
Accepted 25 August 2005
Australian crab spiders Thomisus spectabilis sit on the petals of flowers and ambush prey such as honeybees. White-coloured T. spectabilis reflect in the UV (UV+ spiders) and previous research has shown that their presence, curiously, attracts honeybees to daisies. We applied an UV-absorber (Parsol®) to create UV-absorbing (UV) spiders that did not reflect any light below 395 nm wavelength. These physical changes of visual signals generated by crab spiders caused honeybees to avoid flowers with UV spiders on their petals. They also affected the perception of UV spiders by honeybees and a potential avian predator (blue tits). Compared to UV+ spiders, UV spiders produced less excitation of the UV-photoreceptors in honeybees and blue tits, which translated into a reduced UV-receptor contrast and a reduced overall colour contrast between UV spiders and daisy petals. Our results reveal that a clean physical elimination of reflection in the UV range affects perception in predators and prey and ultimately changes the behaviour of prey.
Key words: Thomisus spectabilis, Apis mellifera, communication, vision, colour signal, ultraviolet