title: Electrophysiological and behavioural characterization of gustatory responses to antennal 'bitter' taste in honeybees.
abstract: We combined behavioural and electrophysiological experiments to study whether bitter taste is perceived at the antennal level in honeybees, Apis mellifera. Our behavioural studies showed that neither quinine nor salicin delivered at one antenna at different concentrations induced a retraction of the proboscis once it was extended in response to 1 M sucrose solution delivered to the opposite antenna. Bees that extended massively their proboscis to 1 M sucrose responded only partially when stimulated with a mixture of 1 M sucrose and 100 mM quinine. The mixture of 1 m sucrose and 100 mM salicin had no such suppressive effect. No behavioural suppression was found for mixtures of salt solution and either bitter substance. Electrophysiological recordings of taste sensillae at the antennal tip revealed sensillae that responded specifically either to sucrose or salt solutions, but none responded to the bitter substances quinine and salicin at the different concentrations tested. The electrophysiological responses of sensillae to 15 mM sucrose solution were inhibited by a mixture of 15 mM sucrose and 0.1 mM quinine, but not by a mixture of 15 mM sucrose and 0.1 mM salicin. The responses of sensillae to 50 mM NaCl were reduced by a mixture of 50 mm NaCl and 1 mM quinine but not by a mixture of 50 mM NaCl and 1 mM salicin. We concluded that no receptor cells for the bitter substances tested, exist at the level of the antennal tip of the honeybee and that antennal bitter taste is not represented as a separate perceptual quality.
authors.affiliation: Centre de Recherches sur la Cognition Animale (UMR 5169), CNRS--Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse cedex 4, France. debrito@cict.fr
authors.forename: Maria Gabriela
authors.initials: MG
authors.lastname: de Brito Sanchez
authors.forename: Martin
authors.initials: M
authors.lastname: Giurfa
authors.forename: Theo Rolla
authors.initials: TR
authors.lastname: de Paula Mota
authors.forename: Monique
authors.initials: M
authors.lastname: Gauthier
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001516:Bees / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D001592:Benzyl Alcohols / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005960:Glucosides; D011803:Quinine / Q000494:pharmacology; D012679:Sense Organs / Q000166:cytology*; D012965:Sodium Chloride / Q000494:pharmacology; D013395:Sucrose / Q000494:pharmacology; D013549:Sweetening Agents / Q000494:pharmacology; D013649:Taste / Q000187:drug effects / Q000502:physiology*; D013650:Taste Buds / Q000187:drug effects / Q000502:physiology; D013652:Taste Threshold
chemical_list: D001592:Benzyl Alcohols; D005960:Glucosides; D013549:Sweetening Agents; D012965:Sodium Chloride; C005696:salicin; D013395:Sucrose; D011803:Quinine