title: Assessment of gustatory responses to different sugars in harnessed and free-moving bumblebee workers (Bombus terrestris).
abstract: For bumblebee colony survival, sugar responses are crucial as nectar is the main carbohydrate source and flower choice is likely determined by sugar composition. This study used a bioassay both with harnessed and with free-moving workers of the bumblebee Bombus terrestris to study the gustatory response to the 3 major plant sugars by both groups. In harnessed workers of B. terrestris, a concentration of 5.5% of fructose and glucose was required to induce the proboscis extension reflex in 50% of the workers, whereas for sucrose, a much higher concentration of 40% was needed. In contrast, free-moving workers given a choice between 30% glucose, 30% sucrose, 30% fructose, and water showed a strong preference for sucrose (66% of individuals) compared with 18% for glucose and 16% for fructose; water was never chosen. Familiarization with 30% fructose provoked a significant increase in preference toward fructose, indicating plasticity. In addition, by amputation of the tarsi, it was found that tarsi plays a role in the sugar response with especially the foreleg tarsi being involved in the response to fructose. Our results demonstrated that sugar response is different in free-moving versus harnessed bumblebee workers and that tarsi plays a role in sugar perception.
authors.affiliation: Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
authors.forename: Veerle
authors.initials: V
authors.lastname: Mommaerts
authors.forename: Felix
authors.initials: F
authors.lastname: Wäckers
authors.forename: Guy
authors.initials: G
authors.lastname: Smagghe
mesh_terms: D000818:Animals; D001516:Bees / Q000187:drug effects* / Q000502:physiology*; D002241:Carbohydrates / Q000494:pharmacology*; D005632:Fructose / Q000494:pharmacology; D007103:Immobilization; D009068:Movement / Q000502:physiology*; D055697:Taste Perception / Q000187:drug effects* / Q000502:physiology*
chemical_list: D002241:Carbohydrates; D005632:Fructose
keywords: Bombus terrestris; harnessed bumblebees; plant sugars; sugar response; tarsi; taste