摘要In the European honey bee(Apis mellifera),the olfactory system is essential for foraging and intraspecific communication via pheromones.Honey bees are equipped with a large repertoire of olfactory receptors belonging to the insect odorant receptor(OR)family.Previous studies have indicated that the transcription level of a few OR types in-cluding OR11,a receptor activated by the queen-released pheromone compound(2E)-9-oxodecenoic acid(9-ODA),is significantly higher in the antenna of males(drones)than in female workers.However,the number and distribution of antennal cells expressing male-biased ORs is elusive.Here,we analyzed antennal sections from bees by in situ hybridiza-tion for the expression of the male-biased receptors OR11,OR18,and OR170.Our results demonstrate that these receptors are expressed in only moderate numbers of cells in the antennae of females(workers and queens),whereas substantially higher cell numbers ex-press these ORs in drones.Thus,the reported male-biased transcript levels are due to sex-specific differences in the number of antennal cells expressing these receptors.De-tailed analyses for OR11 and OR 18 in drone antennae revealed expression in two distinct subsets of olfactory sensory neurons(OSNs)that in total account for approximately 69％of the OR-positive cells.Such high percentages of OSNs expressing given receptors are reminiscent of male-biased Ors in moths that mediate the detection of female-released sex pheromone components.Collectively,our findings indicate remarkable similarities between male antennae of bees and moths and support the concept that male-biased Ors in bee drones serve the detection of female-emitted sex pheromones.