title: Perception of floral volatiles involved in host-plant finding behaviour: comparison of a bee specialist and generalist.
abstract: Specialist and generalist bees use olfactory and visual cues to find and recognise flowering plants. Specialised (oligolectic) bees rely on few host plants for pollen collection. These bee species are suggested to use specific volatiles, but it is unknown whether they have dedicated adaptations for these particular compounds compared to bees not specialised on the same plants. In the present study, we investigated the perception of host odorants and its neuronal substrate with regard to host-plant finding behaviour in oligolectic bees. We reconstructed the antennal lobes (AL) in the Salix specialist, Andrena vaga, and counted about 135 glomeruli and thereby less than the approximately 160 in honeybees. Using calcium imaging experiments to measure neural activity in the bee brain, we recorded odorant-evoked activity patterns in the AL of A. vaga and, for comparison, in the generalist honeybee, Apis mellifera. Our physiological experiments demonstrated that A. vaga bees were particularly sensitive to 1,4-dimethoxybenzene, a behaviour-mediating odorant of Salix host flowers. We found more sensitive glomeruli in the specialised bees as compared to generalist honeybees. This neural adaptation might allow oligolectic A. vaga bees to effectively locate host plants from distances.
authors.affiliation: Institute of Experimental Ecology, University of Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany. hannah.burger@uni-ulm.de
authors.forename: Hannah
authors.initials: H
authors.lastname: Burger
authors.forename: Manfred
authors.initials: M
authors.lastname: Ayasse
authors.forename: Stefan
authors.initials: S
authors.lastname: Dötterl
authors.forename: Sabine
authors.initials: S
authors.lastname: Kreissl
authors.forename: C Giovanni
authors.initials: CG
authors.lastname: Galizia
mesh_terms: D000818:Animals; D000840:Anisoles / Q000494:pharmacology; D057506:Arthropod Antennae / Q000187:drug effects / Q000294:innervation* / Q000378:metabolism; D001516:Bees / Q000145:classification / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects; D020013:Calcium Signaling; D003463:Cues; D004305:Dose-Response Relationship, Drug; D005071:Evoked Potentials; D035264:Flowers; D009812:Odorants; D009833:Olfactory Pathways / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D055696:Olfactory Perception / Q000187:drug effects; D032108:Salix / Q000378:metabolism*; D012903:Smell / Q000187:drug effects; D013997:Time Factors
chemical_list: D000840:Anisoles; C031200:1,4-dimethoxybenzene