title: Bees use honest floral signals as indicators of reward when visiting flowers.
abstract: Pollinators visit flowers for rewards and should therefore have a preference for floral signals that indicate reward status, so called 'honest signals'. We investigated honest signalling in Brassica rapa L. and its relevance for the attraction of a generalised pollinator, the bumble bee Bombus terrestris (L.). We found a positive association between reward amount (nectar sugar and pollen) and the floral scent compound phenylacetaldehyde. Bumble bees developed a preference for phenylacetaldehyde over other scent compounds after foraging on B. rapa. When foraging on artificial flowers scented with synthetic volatiles, bumble bees developed a preference for those specific compounds that honestly indicated reward status. These results show that the honesty of floral signals can play a key role in their attractiveness to pollinators. In plants, a genetic constraint, resource limitation in reward and signal production, and sanctions against cheaters may contribute to the evolution and maintenance of honest signalling.
authors.affiliation: Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland.
authors.forename: A C
authors.initials: AC
authors.lastname: Knauer
authors.forename: F P
authors.initials: FP
authors.lastname: Schiestl
mesh_terms: D000079:Acetaldehyde / Q000031:analogs & derivatives / Q000032:analysis; D000818:Animals; D001516:Bees / Q000502:physiology*; D001522:Behavior, Animal; D029741:Brassica rapa / Q000033:anatomy & histology / Q000502:physiology*; D003463:Cues; D035264:Flowers / Q000033:anatomy & histology / Q000502:physiology; D057048:Plant Nectar; D011058:Pollen; D054817:Pollination; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D057048:Plant Nectar; D055549:Volatile Organic Compounds; D000079:Acetaldehyde; C013192:phenylacetaldehyde
keywords: Floral evolution; learning; phenylacetaldehyde; pollination; volatile; volatile organic compounds (VOC)