Multispectral images of flowers reveal the adaptive significance of using long-wavelength-sensitive receptors for edge detection in bees.
Many pollinating insects acquire their entire nutrition from visiting flowers, and they must therefore be efficient both at detecting flowers and at recognizing familiar rewarding flower types. A crucial first step in recognition is the identification of edges and the segmentation of the visual field into areas that belong together. Honeybees and bumblebees acquire visual information through three types of photoreceptors; however, they only use a single receptor type-the one sensitive to longer wavelengths-for edge detection and movement detection. Here, we show that these long-wavelength receptors (peak sensitivity at ~544 nm, i.e., green) provide the most consistent signals in response to natural objects. Using our multispectral image database of flowering plants, we found that long-wavelength receptor responses had, depending on the specific scenario, up to four times higher signal-to-noise ratios than the short- and medium-wavelength receptors. The reliability of the long-wavelength receptors emerges from an intricate interaction between flower coloration and the bee's visual system. This finding highlights the adaptive significance of bees using only long-wavelength receptors to locate flowers among leaves, before using information provided by all three receptors to distinguish the rewarding flower species through trichromatic color vision.
Bee Sensory and Behavioural Ecology Lab, School of Biological and Chemical Sciences, Queen Mary University of London, London, UK. v.vasas@qmul.ac.uk.
Vera
http://orcid.org/0000-0001-8538-0206
V
Vasas
Department of Biology, Long Island University - Post, Brookville, NY, USA.
Daniel
D
Hanley
School of Environmental Sciences, University of Guelph, Guelph, ON, N3C 2W1, Canada.
Peter G
PG
Kevan
Bee Sensory and Behavioural Ecology Lab, School of Biological and Chemical Sciences, Queen Mary University of London, London, UK.
Lars
L
Chittka
D000818:Animals; D001516:Bees / Q000502:physiology*; D003118:Color Perception / Q000502:physiology*; D055253:Color Vision / Q000502:physiology*; D035264:Flowers; D017711:Nonlinear Dynamics; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology*; D054817:Pollination; D017603:Signal Detection, Psychological; D059629:Signal-To-Noise Ratio
Color processing; Receptor adaptation; Signal-to-noise ratio; Visual ecology; Visual processing