Comportement reproducteur et communication sexuelle phéromonale chez les abeilles du genre Apis.

par Florian Bastin

Projet de thèse en Sciences de la vie et de la santé

Sous la direction de Jean-christophe Sandoz.

Thèses en préparation à Paris Saclay , dans le cadre de Structure et Dynamique des Systèmes Vivants , en partenariat avec Évolution, Génomes, Comportement et Écologie (laboratoire) , EVOLBEE - Evolution et comportements de l'abeille (equipe de recherche) et de Université Paris-Sud (établissement de préparation de la thèse) depuis le 01-11-2012 .


  • Résumé

    Pour la reproduction, les mâles d'abeilles se regroupent dans des zones de congrégation. Ensuite les reines vierges rejoignent les congrégations et s'accouplent avec une douzaine de mâles. Nous avons démontré qu'il existe une interattraction des mâles et une attraction des reines vierges envers les mâles. Ces résultats expliquent la formation des congrégations et suggèrent une possible existence d'une phéromone de mâles que nous cherchons à déterminer chimiquement. Nous proposons aussi un atlas détaillé du premier centre de traitement de l'information olfactive (le lobe antennaire) des 3 castes d'abeilles, les reines, ouvrières et mâles. La stratégie caractéristique d'accouplement des abeilles est la même chez les 9 espèces du genre Apis. Cependant il existe des variations chimiques dans la phéromone de reine propre à chaque espèce. Notre étude des lobes antennaires montre des différences dans le nombre et la position des macroglomérules des mâles abeilles du genre Apis.

  • Titre traduit

    Mating behaviour and pheromonal sex communication in honey bees of the Apis genus


  • Résumé

    The domesticated honeybee, Apis mellifera, is the economically most valuable animal pollinator for a majority of fruit, nut, vegetable, and seed crops world-wide. Due to this social insect's rich behavioral repertoire and cognitive abilities, honeybees have also become a main-stream animal model for scientific studies in fields such as ethology, neurobiology, and animal cognition. Yet, for all the knowledge acquired on this model organism, crucial aspects of its reproductive behavior, knowledge of which is essential for optimization of beekeeping strategies, still remain elusive. During mating season, several thousand male honeybees, the drones, gather in drone congregation areas (DCA) 10-40 m above ground. When a receptive female, a virgin queen, enters the DCA, drones are attracted to her first by olfactory cues (pheromones) and on shorter range by visual cues. Drones compete for the queen in flight, scrambling for a good position to approach her and within 15-30 minutes the queen mates in mid-air with typically 10-20 drones, who die after copulation. It is not fully understood yet, how drones and virgin queens find the DCAs; horizontal cues are most probably important and the possible existence of drone-produced aggregation pheromones has been proposed, but was never demonstrated. We investigated innate odor preferences of drones under controlled laboratory conditions using a locomotion compensator based walking simulator. First, we tested the behavioral responses of drones to 9-oxo-2-decenoic acid (9-ODA), the main component of queen sex pheromone, and to queen mandibular pheromone (QMP), which contains additional queen-derived components and is known to be an important social regulator of queen-worker interaction. While 9-ODA is highly abundant in the odor bouquet of virgin queens, QMP rather resembles the odor bouquet of a mated queen and a differential behavioral response would be adaptive for drones. Indeed, drones were attracted by 9-ODA, but not by QMP in our behavioral assay. Next, we investigated attractive effects of male-derived odors and their possible role in the formation of DCAs. We used odor bouquet of groups of living drones or workers and tested drones' behavioral responses in the walking simulator. Our results confirm for the first time, that honeybee drones are attracted by groups of other drones but not by workers (Brandstaetter et al., In press). Drones are composing a caste specially adapted for mating and their olfactory system is tuned for sex communication. The drone, Apis mellifera, antennal lobe (AL), the primary olfactory center of the insect brain, features 4 hypertrophied functional units, the macroglomeruli. Recently, the largest macroglomerulus MG2 has been shown to respond specifically to 9-ODA. But it is not known how odors, involved in sex communication, are processed in the AL of drones and to which odors the 3 remaining macroglomeruli respond to. The main aspects of mating behavior are apparently conserved in bees of the different species, with 9-ODA seeming generally attractive to drones. However, it is found that ratio and chemical blend of mandibular gland pheromones in virgin queens differ within Apis gender. The AL study of drones from different Apis species will help us to understand the evolution of mating behavior. Our results indicate an apparent complexification of AL between so-called ancestral species (dwarf and giant honeybees) and the most derived one (cavity-nesting honeybees). Brandstatetter, A.S., Bastin F., Sandoz J-C. (In press). Honeybee drones are attracted by groups of consexuals in a walking simulator. The Journal of Experimental Biology