Octopamine affects gustatory responsiveness and may enhance learning in bumble bees

Octopamine has broad roles within invertebrate nervous systems as a neurohormone, neurotransmitter, and neuromodulator. It orchestrates foraging behavior in many insect taxa via effects on feeding, gustatory responsiveness, and appetitive learning. Knowledge of how this biogenic amine regulates bee physiology and behavior is based largely on study of a single species, the honey bee, Apis mellifera. Until recently, its role in the foraging ecology and social organization of diverse bee taxa had been unexplored. Bumble bees (Bombus spp.) are a model for research into the neural basis of foraging and learning, but whether octopamine similarly affects sensory and cognitive performance in this genus is not known. To address this gap, we explored the effects of octopamine on gustatory responsiveness and associative learning in Bombus impatiens via conditioning of the proboscis extension reflex (PER) using a visual (color) cue. We found that octopamine had similar effects on bumble bee behavior as previously reported in honey bees; however, higher doses were required to induce these effects. At this higher dose, octopamine lowered bees' gustatory responsiveness and appeared to enhance associative learning performance during the early phase of our experiment. Adding to recent studies on stingless bees (Meliponini), these findings support the idea that octopamine's role in reward perception and processing is broadly conserved across Apidae, while pointing towards some differences across systems worth exploring further.

Automated summary

Octopamine has diverse effects on invertebrate nervous systems and plays a role in foraging behavior and learning. The role of octopamine in bumble bees, a model species for foraging and learning research, was explored. It was found that octopamine had similar effects on bumble bees as honey bees, but higher doses were required.