ORIGINAL PAPER Evidence of red sensitive photoreceptors in Pygopleurus israelitus (Glaphyridae: Coleoptera) and its implications for beetle pollination in the southeast Mediterranean J. Martı ´nez-Harms • M. Vorobyev • J. Schorn • A. Shmida • T. Keasar • U. Homberg • F. Schmeling • R. Menzel Received: 4 October 2011 / Revised: 22 March 2012 / Accepted: 26 March 2012 / Published online: 18 April 2012 Ó Springer-Verlag 2012 Abstract A very well-documented case of flower-beetle interaction is the association in the Mediterranean region between red bowl-shaped flowers and beetles of the family Glaphyridae. The present study examines the visual mechanisms by which Pygopleurus israelitus (Glaphyri- dae: Scarabaeoidea: Coleoptera) would perceive the colors of flowers they visit by characterizing the spectral sensi- tivity of its photoreceptors. Our measurements revealed the presence of three types of photoreceptors, maximally sen- sitive in the UV, green and red areas of the spectrum. Using color vision space diagrams, we calculated the distribution of beetle-visited flower colors in the glaphyrid and hon- eybee color space and evaluated whether chromatic dis- crimination differs between the two types of pollinators. Respective color loci in the beetle color space are located on one side of the locus for green foliage background, whereas in the honeybee the flower color loci surround the locus occupied by green foliage. Our results represent the first evidence of a red sensitive photoreceptor in a flower- visiting coleopteran species, highlighting Glaphyridae as an interesting model group to study the role of pollinators in flower color evolution. Keywords Coleoptera  Pollination  Color vision  Flower colors  Color space Introduction According to the concept of pollination syndromes, com- binations of floral traits reflect specialization to certain type of pollinators. Along this idea, some authors have proposed that the tendency of pollination systems to specialize (Stebbins 1970; Crepet 1983, 1984) leads to tight co-evo- lution between plants and pollinators (Gilbert and Raven 1975). Floral colors play a key role in flower/pollinator interactions and under a scenario of mutual specialization, some authors have speculated on the potential for adapta- tion of pollinators’ color vision to optimize flower detec- tion (Chittka 1996; Vorobyev and Menzel 1999). Despite the fact that the color vision of the two most exten- sively studied insect pollinator groups, hymenopterans and lepidopterans, allows good discrimination of a wide range of colors, systematic studies have not revealed clear trends of spectral tuning of their color vision to the spectral properties of the flowers they visit (Chittka and Menzel 1992; Vorobyev and Menzel 1999; Briscoe and Chittka 2001; Vorobyev et al. 2001a, b; Stavenga and Arikawa 2006). Regardless of the lifestyle of the particular species, J. Martı ´nez-Harms (&)  J. Schorn  R. Menzel FU Biologie, Institut fu ¨ r Biologie-Neurobiologie, Freie Universita ¨t Berlin, Ko ¨nigin-Luise Str. 28/30, 14195 Berlin, Germany e-mail: j.martinez-harms@fu-berlin.de M. Vorobyev Department of Optometry and Vision Science, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand A. Shmida Department of Ecology, Evolution and Behavior, Center for the Study of Rationality, The Hebrew University, 91904 Jerusalem, Israel T. Keasar Department of Biology and Environment, University of Haifa-Oranim, 36006 Tivon, Israel U. Homberg  F. Schmeling Fachbereich Biologie-Neurobiologie/Ethologie, Philipps-Universita ¨t Marburg, Karl von Frisch Str. 8, 35032 Marburg, Germany 123 J Comp Physiol A (2012) 198:451–463 DOI 10.1007/s00359-012-0722-5