Somatotopic Organization of Sensory Inputs From Taste Appendages in the Subesophageal Zone and Brain of the Honey Bee Apis mellifera

ABSTRACT

The study of gustatory pathways from the periphery to the brain offers valuable insights into the neural mechanisms underlying taste processing and foraging choices, particularly in ecologically and economically relevant species such as the honey bee, Apis mellifera . While the neural substrates of other sensory modalities in bees, notably olfaction and vision, have been thoroughly characterized, the organization principles of gustatory pathways in the primary gustatory center (the subesophageal zone, SEZ) and brain of this species remain largely unexplored. Using anterograde mass staining with dextran‐coupled fluorescent tracers applied into the main gustatory appendages (antennae, mouthparts, and foreleg tarsi), we identified the projection areas of their sensory afferents within the SEZ. Our results show that sensory circuits are confined to specific, distinct regions of the SEZ, suggesting the presence of somatotopic “maps” corresponding to the different appendages. Overlaps between projections, reflecting potential information exchange between appendicular domains in the SEZ, were most evident among inputs originating from similar appendages (e.g., between mouthparts—proboscis and mandibles) and were limited between domains of different appendages (e.g., antennae and mouthparts). We also confirm the subesophageal‐calycal tract (SCT) as the main output of the SEZ. Combined retrograde staining of the SCT and anterograde staining of taste appendages revealed that SCT dendrites overlap specifically with sensory input from the maxillae in the SEZ. The functional significance of these findings is discussed in the context of gustatory information processing during bee feeding behavior, and the results are considered within a comparative framework across insect taxa.