Authors: Sarah Papiorek Katja Rohde Klaus Lunau
Publish Date: 2013/05/31
Volume: 100, Issue: 7, Pages: 633-643
Abstract
Variability in flower colour of animalpollinated plants is common and caused inter alia by interindividual differences in pigment concentrations If and how pollinators especially bees respond to these small differences in pigment concentration is not known but it is likely that flower colour variability impacts the choice behaviour of all flower visitors that exhibit innate and learned colour preferences In behavioural experiments we simulated varying pigment concentrations and studied its impact on the colour choices of bumblebees and honeybees Individual bees were trained to artificial flowers having a specific concentration of a pigment ie Acridine Orange or Aniline Blue and then given the simultaneous choice between three test colours including the training colour one colour of lower and one colour of higher pigment concentration For each pigment two setups were provided covering the range of low to middle and the range of middle to high pigment concentrations Despite the small beesubjective perceptual contrasts between the tested stimuli and regardless of training towards medium concentrations bees preferred neither the training stimuli nor the stimuli offering the highest pigment concentration but more often chose those stimuli offering the highest spectral purity and the highest chromatic contrast against the background Overall this study suggests that bees choose an intermediate pigment concentration due to its optimal conspicuousness It is concluded that the spontaneous preferences of bees for flower colours of high spectral purity might exert selective pressure on the evolution of floral colours and of flower pigmentation
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