Honeybee drones are attracted by groups of consexuals in a walking simulator

Abstract

During the mating season, honeybee males, the drones, gather in congregation areas 10-40 m above ground. When a receptive female, a queen, enters the congregation, drones are attracted to her by queen-produced pheromones and visual cues and attempt to mate with the queen in mid-air. It is still unclear how drones and queens find the congregations. Visual cues on the horizon are most probably used for long-range orientation. For shorter-range orientation, however, attraction by a drone-produced aggregation pheromone has been proposed, yet so far its existence has not been confirmed conclusively. The low accessibility of congregation areas high up in the air is a major hurdle and precise control of experimental conditions often remains unsatisfactory in field studies. Here, we used a locomotion compensator-based walking simulator to investigate drones' innate odor preferences under controlled laboratory conditions. We tested behavioral responses of drones to 9-oxo-2-decenoic acid (9-ODA), the major queen-produced sexual attractant, and to queen mandibular pheromone (QMP), an artificial blend of 9-ODA and several other queen-derived components. While 9-ODA strongly dominates the odor bouquet of virgin queens, QMP rather resembles the bouquet of mated queens. In our assay, drones were attracted by 9-ODA, but not by QMP. We also investigated the potential attractiveness of male-derived odors by testing drones' orientation responses to the odor bouquet of groups of 10 living drones or workers. Our results demonstrate that honeybee drones are attracted by groups of other drones (but not by workers), which may indicate a role of drone-emitted cues for the formation of congregations.

Virgin queen attraction toward males in honey bees

“…‘during’ phase). Our system was designed to provide clear criteria for measuring whether or not a bee is attracted to an odour and to allow maximal control over experimental conditions 50 . Indeed in the preliminary experiment, appetitively conditioned bees clearly chose to remain in the odour quadrant and walked longer distances in this quadrant compared to control bees (Supplementary Experiment 1).…”

“…However, due to the difficulties of testing these ideas in natural mating conditions, research in this direction has little progressed since then. Recently, we tested this hypothesis in the laboratory by using tethered drones freely-walking on an air-suspended trackball 50 . Our study demonstrated that honeybee drones are indeed attracted to the odour bouquet from a group of drones 50 .…”

“…Recently, we tested this hypothesis in the laboratory by using tethered drones freely-walking on an air-suspended trackball 50 . Our study demonstrated that honeybee drones are indeed attracted to the odour bouquet from a group of drones 50 . These data clearly suggest that a drone-produced attractive odour substance may be involved in the formation of drone congregations.…”

“…If this is the case, an especially interesting possibility is that virgin queens may also use such a cue when orienting toward drone congregations. In the present study, we thus explored the olfactory preferences of virgin queens under controlled experimental conditions using our walking simulator 50 . As a preliminary step, we demonstrated with an olfactory information transfer experiment on workers that the attractiveness of an odorant is translated in the walking simulator by an increase in the time spent and in the distance travelled by the animal in the odour (Supplementary Experiment 1).…”

Walking patterns induced by learned odors in the honeybee,Apis melliferaL.

“…We used a locomotion compensator-based walking simulator similar to other designs (Brandstaetter et al, 2014). It consisted of a Styrofoam sphere (5 cm in diameter, 2.2 g) positioned in a modified plastic funnel and suspended on an air cushion formed by air flowing into the funnel from its neck (Fig.…”