title: Host choice in a bivoltine bee: how sensory constraints shape innate foraging behaviors.
abstract: BACKGROUND
  Many insects have multiple generations per year and cohorts emerging in different seasons may evolve their own phenotypes if they are subjected to different selection regimes. The bivoltine bee Andrena bicolor is reported to be polylectic and oligolectic (on Campanula) in the spring and summer generations, respectively. Neurological constraints are assumed to govern pollen diet in bees. However, evidence comes predominantly from studies with oligolectic bees. We have investigated how sensory constraints influence the innate foraging behavior of A. bicolor and have tested whether bees of different generations evolved behavioral and sensory polyphenism to cope better with the host flowers available in nature when they are active.
  
  
  RESULTS
  Behavioral and sensory polyphenisms were tested in choice assays and electroantennographic analyses, respectively. In the bioassays, we found that females of both generations (1) displayed a similar innate relative reliance on visual and olfactory floral cues irrespective of the host plants tested; (2) did not prefer floral cues of Campanula to those of Taraxacum (or vice versa) and (3) did not display an innate preference for yellow and lilac colors. In the electroantennographic analyses, we found that bees of both generations responded to the same set of compounds.
  
  
  CONCLUSIONS
  Overall, we did not detect seasonal polyphenism in any trait examined. The finding that bees of both generations are not sensory constrained to visit a specific host flower, which is in strict contrast to results from studies with oligolectic bees, suggest that also bees of the second generation have a flexibility in innate foraging behavior and that this is an adaptive trait in A. bicolor. We discuss the significance of our findings in context of the natural history of A. bicolor and in the broader context of host-range evolution in bees.
authors.affiliation: Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Helmholtzstraße 10-1, 89081, Ulm, Germany. miletpinheiro@hotmail.com.|Departamento de Química Fundamental, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, s/n, Recife, 50670-901, Brazil. miletpinheiro@hotmail.com.
authors.forename: Paulo
authors.initials: P
authors.lastname: Milet-Pinheiro
authors.affiliation: Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Helmholtzstraße 10-1, 89081, Ulm, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Herz
authors.affiliation: Department of Ecology and Evolution, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Dötterl
authors.affiliation: Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Helmholtzstraße 10-1, 89081, Ulm, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Ayasse
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology*; D029422:Campanulaceae; D003118:Color Perception; D003463:Cues; D005247:Feeding Behavior; D005260:Female; D005518:Food Preferences; D008297:Male; D055696:Olfactory Perception; D012677:Sensation; D031205:Taraxacum
keywords: Andrena bicolor; Campanula; Olfactory and visual cues; Oligolecty; Polylecty; Seasonal polyphenism