Caste-specific proboscis extension responses in honey bees to sucrose and royal jelly stimuli

Understanding the nutritional preferences of honey bees (Apis mellifera) is essential for comprehending their behavioral ecology and the division of labor within a colony. While gustatory sensitivity to sucrose is well-documented in workers, a significant research gap exists regarding the sensory responses of queens and their reactions to caste-specific nutrition such as royal jelly. This study utilized the proboscis extension response (PER) assay to compare the food preferences of three distinct bee categories: foragers, 1-day-old workers, and queens. Subjects were presented repeatedly, in a pseudorandom order, with water, sucrose, royal jelly, and a sucrose-royal jelly mixture as gustatory stimuli. Foragers exhibited a high responsiveness to sucrose and showed uniformly low responsiveness to other stimuli. Although 1-day-old workers showed high responsiveness to sucrose, unlike foragers, they also responded to the sucrose-royal jelly mixture. Queens displayed a unique response profile, with near-ceiling responsiveness to both royal jelly and the mixture, followed by response to sucrose solution without habituation. Additionally, responsiveness to the sucrose was higher in foragers than in 1-day-old workers. These findings suggest that the honey bee gustatory and sensory system is tuned to the specific nutritional requirements of caste and age.