![]() Drones follow the virgin queen in a comet-like swarm and engage in a scramble competition, each individual struggling for the most promising position to approach and mate with the queen 38. As soon as a virgin queen is present, many drones are attracted to her, both by olfactory signals (the mandibular gland sex pheromone, 9-oxo-2-decenoic acid, 9-ODA) and by visual cues at shorter range 12, 38. Then, about one hour after the peak of drones’ departure, virgin queens leave the hive and fly to the vicinity of the drone congregation 7, 25, 37. These drone congregations can contain as many as 11,000 drones from up to 240 different colonies 33, 34, 35, 36. During the mating season, and on favourable weather conditions, honeybee males, the drones, fly out and gather high in the air at discrete congregation areas located usually 10–40 m above ground, with a diameter of 30–200 m 7, 31, 32, 33. Honeybees display a particularly striking mating behaviour 24, 25, 26, 27, 28, 29, 30. Honeybees are eusocial insects, characterized by a reproductive division of labor between one fertile female, the queen and thousands of facultatively sterile females, the workers 17. A good example is the honeybee Apis mellifera, a worldwide economically valuable pollinator and a main-stream scientific model in diverse fields such as genetics, physiology, ethology, neurobiology and animal cognition 16, 17, 18, 19, 20, 21, 22, 23. Even in some well-studied species their existence and role are still unclear. The importance of male-produced pheromones for bee reproduction has long been underestimated, probably because they were less intensively studied. ![]() These spots are attractive to females but also to conspecific males in some Andrenidae 13, and Apidae, like carpenter bees 9, bumble bees 14 and orchid bees 15. In some cases, the male secretions produced by the mandibular glands or the labial glands are also used to mark spots along male flight paths. They induce male attraction in some Colletidae 4, Andrenidae 8 and Apidae like carpenter bees 9, stingless bees 10, bumble bees 11 and honey bees 12. Female exocrine secretions from the mandibular glands are the most common bee sex pheromones. ![]() Bees have large glandular systems allowing both females and males to produce sex pheromones which attract conspecifics. Sex pheromones are defined as odours, produced by either males or females, which stimulate behavioural reactions and/or induce physiological effects in the opposite sex, bringing the sexes together for the purpose of mating 2. Despite this diversity of mating strategies, many bee species are known to use sex pheromones for reproduction 2. Colletes cunicularius 4 and Centris pallida 5), others at resource-based sites ( Anthidium manicatum 6), while still others use nuptial flyways ( Apis species 7). Some species mate at the female emergence site (e.g. Similar content being viewed by othersīees (Hymenoptera: Apoidea: Anthophila) represent more than 20,000 species, from solitary to eusocial, which display a wide spectrum of mating behaviours 1, 2, 3. Interpreted in the context of mating, these results may suggest that virgin queens use volatile olfactory cues from the drones to find the congregations. In addition, non-sexually receptive females (workers) of the same age are not attracted to the drone odour bouquet. They are not attracted to the bouquet from a group of workers. We show that sexually-mature virgin queens are attracted to the odour bouquet from a group of living drones. We thus tested virgin queens’ olfactory orientation on a walking simulator in which they have full control over odour stimulation. Beside visual cues for long-range orientation, queens may use olfactory cues. It is still unclear which sensory cues help virgin queens find drone congregations in the first place. Virgin queens join the vicinity of the congregation after it has formed, and mate with as many as 20 males in mid-air. Converging evidence suggests that drones emit a pheromone that can attract other drones, thereby increasing the size of the congregation. During the mating season, honeybee males, the drones, gather in congregations 10–40 m above ground. Although the honeybee is a crucial agricultural agent and a prominent scientific model organism, crucial aspects of its reproductive behaviour are still unknown.
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