title: Bumble bees regulate their intake of essential protein and lipid pollen macronutrients.
abstract: Bee population declines are linked to the reduction of nutritional resources due to land-use intensification, yet we know little about the specific nutritional needs of many bee species. Pollen provides bees with their primary source of protein and lipids, but nutritional quality varies widely among host-plant species. Therefore, bees might have adapted to assess resource quality and adjust their foraging behavior to balance nutrition from multiple food sources. We tested the ability of two bumble bee species, Bombus terrestris and Bombus impatiens, to regulate protein and lipid intake. We restricted B. terrestris adults to single synthetic diets varying in protein:lipid ratios (P:L). The bees over-ate protein on low-fat diets and over-ate lipid on high-fat diets to reach their targets of lipid and protein, respectively. The bees survived best on a 10:1 P:L diet; the risk of dying increased as a function of dietary lipid when bees ate diets with lipid contents greater than 5:1 P:L. Hypothesizing that the P:L intake target of adult worker bumble bees was between 25:1 and 5:1, we presented workers from both species with unbalanced but complementary paired diets to determine whether they self-select their diet to reach a specific intake target. Bees consumed similar amounts of proteins and lipids in each treatment and averaged a 14:1 P:L for B. terrestris and 12:1 P:L for B. impatiens These results demonstrate that adult worker bumble bees likely select foods that provide them with a specific ratio of P:L. These P:L intake targets could affect pollen foraging in the field and help explain patterns of host-plant species choice by bumble bees.
authors.affiliation: Department of Entomology, Center for Pollinator Research, The Pennsylvania State University, 501 ASI Building, University Park, PA 16802, USA adv124@psu.edu.
authors.forename: A D
authors.identifier: 0000-0001-5268-5580
authors.initials: AD
authors.lastname: Vaudo
authors.affiliation: Centre for Behaviour and Evolution, Institute of Neuroscience, Henry Wellcome Building for Neuroecology, Newcastle University, Framlington Place, Newcastle Upon Tyne NE2 4HH, UK.
authors.forename: D
authors.initials: D
authors.lastname: Stabler
authors.affiliation: Department of Entomology, Center for Pollinator Research, The Pennsylvania State University, 501 ASI Building, University Park, PA 16802, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Patch
authors.affiliation: Department of Entomology, Center for Pollinator Research, The Pennsylvania State University, 501 ASI Building, University Park, PA 16802, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Tooker
authors.affiliation: Department of Entomology, Center for Pollinator Research, The Pennsylvania State University, 501 ASI Building, University Park, PA 16802, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Grozinger
authors.affiliation: Centre for Behaviour and Evolution, Institute of Neuroscience, Henry Wellcome Building for Neuroecology, Newcastle University, Framlington Place, Newcastle Upon Tyne NE2 4HH, UK.
authors.forename: G A
authors.initials: GA
authors.lastname: Wright
mesh_terms: D000818:Animals; D001516:Bees / Q000187:drug effects / Q000502:physiology*; D001681:Biological Assay; D004032:Diet; D004041:Dietary Fats / Q000494:pharmacology*; D004044:Dietary Proteins / Q000494:pharmacology*; D005247:Feeding Behavior / Q000187:drug effects; D008055:Lipids / Q000737:chemistry*; D011058:Pollen / Q000187:drug effects / Q000378:metabolism*; D016016:Proportional Hazards Models; D016019:Survival Analysis
chemical_list: D004041:Dietary Fats; D004044:Dietary Proteins; D008055:Lipids
keywords: Foraging behavior; Geometric framework; Nutrient regulation; Nutritional ecology; Pollination; Pollinator health