Tactile learning in resin foraging honeybees
Honeybees harvest and use plant resins in a mixture called propolis to seal cracks and smooth surfaces in the nest architecture. Resins in the nest may be important in maintaining a healthy colony due to their antimicrobial properties. This study had two main objectives: (1) Provide initial insight on the learning capabilities of resin foraging honeybees; (2) analyze the sensitivity of resin foraging honeybees to tactile stimuli to elucidate its possible role as a mechanism behind resin foraging. The first objective provides insight into the phenotype of these bees as compared to other forager types, while the second creates a starting point for further work on behavioral mechanisms of resin foraging. Using tactile proboscis extension response conditioning, we found that resin foragers learned to associate two different tactile stimuli, the presence of a gap between two plates and a rough sandpaper surface, with a sucrose reward significantly better than pollen foragers. The results of differential tactile conditioning exhibited no significant difference in the ability of resin foragers to discriminate between smooth and rough surfaces as compared to pollen foragers. We also determined that the sucrose response thresholds (SRTs) of returning resin foragers were lower compared to returning pollen foragers, but both resin foragers and pollen foragers learned a floral odor equally well. This is the first study to examine SRTs and conditioning to tactile and olfactory stimuli with resin foraging honeybees. The results provide new information and identify areas for future research on resin collectors, an understudied foraging phenotype.