KIRKTON, R*; THORN, R.S.: Turning On Smell: Nitic Oxide and the Maturation of the Honeybee Olfactory System

Freshly eclosed honeybees, Apis mellifera, are known to have poor sensitivity to odor, but subsequently ‘turn on’ their olfactory system within 5-10 days after emergence. We repeated these behavioral experiments and found that young bees can distinguish odors by contact within a day after they emerge, but need 4-6 days to develop responsiveness to airborne odors. Electroantennagrams (EAGs) correlated a reduced sensory cell response with this lack of sensitivity to airborne chemicals. NOS figures prominently in the bee olfactory system, where it aids odor memory. When we examined young bee brains for distribution and levels of NOS, they were lower in young bee antennal lobes. If young bees were forced to mature quickly by isolation from the hive, they showed increased sensitivity to airborne odors, an increased EAG response, and elevated NOS levels. Since NOS in the antennal lobe is from antennal sensory cells, these results suggest that young bees must modify these cells’ chemical sensitivity and NOS levels in order to become sensitive to airborne odors. Whether these events are causative or merely correlative remains to be investigated.