title: Impact of pollen resources drift on common bumblebees in NW Europe.
abstract: Several bee species are experiencing significant population declines. As bees exclusively rely on pollen for development and survival, such declines could be partly related to changes in their host plant abundance and quality. Here, we investigate whether generalist bumblebee species, with stable population trends over the past years, adapted their diets in response to changes in the distribution and chemical quality of their pollen resources. We selected five common species of bumblebee in NW Europe for which we had a precise description of their pollen diet through two time periods ('prior to 1950' and '2004-2005'). For each species, we assessed whether the shift in their pollen diet was related with the changes in the suitable area of their pollen resources. Concurrently, we evaluated whether the chemical composition of pollen resources changed over time and experimentally tested the impact of new major pollen species on the development of B. terrestris microcolonies. Only one species (i.e. B. lapidarius) significantly included more pollen from resources whose suitable area expanded. This opportunist pattern could partly explain the expansion of B. lapidarius in Europe. Regarding the temporal variation in the chemical composition of the pollen diet, total and essential amino acid contents did not differ significantly between the two time periods while we found significant differences among plant species. This result is driven by the great diversity of resources used by bumblebee species in both periods. Our bioassay revealed that the shift to new major pollen resources allowed microcolonies to develop, bringing new evidence on the opportunist feature of bumblebee in their diets. Overall, this study shows that the response to pollen resource drift varies among closely related pollinators, and a species-rich plant community ensures generalist species to select a nutrient-rich pollen diet.
authors.affiliation: Research Institute for Biosciences, University of Mons (UMONS), Place du Parc 20, B-7000, Mons, Belgium.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Roger
authors.affiliation: Research Institute for Biosciences, University of Mons (UMONS), Place du Parc 20, B-7000, Mons, Belgium.|Evolutionary Biology & Ecology, Université Libre de Bruxelles (ULB), Av. F.D. Roosevelt 50, B-1050, Brussels, Belgium.
authors.forename: Romain
authors.initials: R
authors.lastname: Moerman
authors.affiliation: Departamento de Ecologia, Universidade de Brasília, Campus Universitário Darcy Ribeiro, Brasília - DF, 70910-900, Brazil.|Center for Ecology, Evolution and Environmental Changes (CE3C), Faculdade de Ciencias da Universidade de Lisboa, 1749-016, Lisboa, Portugal.
authors.forename: Luísa Gigante
authors.initials: LG
authors.lastname: Carvalheiro
authors.affiliation: Naturalis Biodiversity Center, Biodiversity Dynamics, postbus 9517, 2300 RA, Leiden, The Netherlands.|Institute for Biodiversity and Ecosystems Dynamics (IBED) -Computational Geo-Ecology, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Jesús
authors.initials: J
authors.lastname: Aguirre-Guitiérrez
authors.affiliation: Earth and Life Institute - Research group Genetics, Reproduction, Populations, University of Louvain, Croix du Sud 2, Box L7.05.14, 1348, Louvain-la-Neuve, Belgium.
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Jacquemart
authors.affiliation: Alterra, Center for Ecosystem studies, Droevendaalsesteeg 3, P.O. Box 47, 6700 AA, Wageningen, The Netherlands.|Nature Conservation and Plant Ecology Group, Wageningen University, Bornsesteeg 69, 6708 PD, Wageningen, The Netherlands.
authors.forename: David
authors.initials: D
authors.lastname: Kleijn
authors.affiliation: Unit of Analytical Chemistry, University of Liège, Gembloux Agro-Bio Tech, Passage des Déportés 2, B-5030, Gembloux, Belgium.
authors.forename: Georges
authors.initials: G
authors.lastname: Lognay
authors.affiliation: Earth and Life Institute - Research group Genetics, Reproduction, Populations, University of Louvain, Croix du Sud 2, Box L7.05.14, 1348, Louvain-la-Neuve, Belgium.
authors.forename: Laura
authors.initials: L
authors.lastname: Moquet
authors.affiliation: Earth and Life Institute - Research group Genetics, Reproduction, Populations, University of Louvain, Croix du Sud 2, Box L7.05.14, 1348, Louvain-la-Neuve, Belgium.
authors.forename: Muriel
authors.initials: M
authors.lastname: Quinet
authors.affiliation: Research Institute for Biosciences, University of Mons (UMONS), Place du Parc 20, B-7000, Mons, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Rasmont
authors.affiliation: Industrial Biological Chemistry unit, University of Liège, Gembloux Agro-Bio Tech, Passage des Déportés 2, B-5030, Gembloux, Belgium.
authors.forename: Aurore
authors.initials: A
authors.lastname: Richel
authors.affiliation: Research Institute for Biosciences, University of Mons (UMONS), Place du Parc 20, B-7000, Mons, Belgium.
authors.forename: Maryse
authors.initials: M
authors.lastname: Vanderplanck
authors.affiliation: Research Institute for Biosciences, University of Mons (UMONS), Place du Parc 20, B-7000, Mons, Belgium.
authors.forename: Denis
authors.initials: D
authors.lastname: Michez
mesh_terms: D000818:Animals; D001516:Bees; D004032:Diet; D005060:Europe; D005247:Feeding Behavior; D010944:Plants; D011058:Pollen
keywords: bumblebee; diet performance; floral resources; food choices; land-use change; pollen