“Distribution of colours and sugar rewards in the bee’s natural environment”.

WERTLEN, A. M.; HEMPEL DE IBARRA, N.; COCUCCI A. A.; SÉRSIC, A.; KREISCH, W.; RISTOW, M.

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Congreso; 3rd European Congress on Social Insects - Meeting of European Sections of the IUSSI; 2005

3rd European Congress on Social Insects - Meeting of European Sections of the IUSSI St. Petersburg, Russia 22-27 . 2005  Distribution of colours and sugar rewards in the bee’s natural environment   Anna M. Wertlen1 N. Hempel de Ibarra1,2 A.A. Cocucci3 A. Sersic3 W. Kreisch4 and M. Ristow5  1 Free University of Berlin, Institute of Biology, Neurobiology, Königin-Luise-Str.28/30, 14195 Berlin, Germany; e-mail: AMWertlen@gmx.net, nhempel@neurobiologie.fu-berlin.de 2 University of Sussex, School of Life Sciences, Brighton, Falmer, BN1 9QG, UK 3 National University of Cordoba, Facultad de Ciencias Exactas, Físicas y Naturales, Ob. Trejo 242, Av. Haya de la Torre, Córdoba, Argentina   4 Free University of Berlin, Botanical Museum, Königin-Luise-Str.6-8, 14195 Berlin, Germany  5 University of Potsdam, Institute of Biochemistry and Biology, Maulbeerallee 2, 14469 Potsdam, Germany  Keywords: bee, colour, vision, flower, reward, foraging  Bees choose their preferred food source on the basis of profitability, but floral food sources advertise themselves in a wide range of colours. Thus during foraging a bee has to sample a number of colour-reward pairings in a flower patch in order to find the most profitable ones. Since sampling represents a cost, it would be reasonable for a short-living insect to have efficient sampling strategies or biases. One sampling bias may manifest itself as a so-called innate colour preference, which has been described for honeybees under experimental conditions in the laboratory (Giurfa et al. 1995). That finding is mitigated by the fact that honeybees can rapidly learn any colour and recall it for a long time (Menzel 1967). Consequently, the hypothesis was suggested that innate colour preferences lead inexperienced foragers to the best-rewarding flowers, ultimately benefiting the young bees (Giurfa et al. 1995). Alternatively, we suggest that colour-reward pairings in the bee’s environment might occur as non-continuous patterns, thus reducing the cost of sampling. To test these assumptions, we surveyed the floral colours as perceived through bee eyes, and the nectar rewards in natural areas. We recorded reflectance spectra, display sizes, abundance, types of flower shape, nectar properties and pollinator visits of 10-15 co-flowering species over 5-10 days in each of eight areas. Colour properties were described using the RNL-model of honeybee colour vision (Vorobyev et al. 2001). We found a large range of colours and rewards in simultaneously flowering plants in each area. Subsequent analyses showed that flowers with colours innately preferred by bees are not easier to detect; visiting them does not guarantee the highest probability of finding best or most abundant rewards. We describe how pollinators may rapidly assess colour-reward pairings based on colour generalisation and an averaging reward evaluation (Fülöp and Menzel 2000).   References  Fülöp, A. and R. Menzel, 2000. Risk-indifferent foraging behaviour in honeybees. Anim. Behav., 60: 657-666.