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Facing the loss of meliferous bee colonies, beekeepers are becoming more and more interested in genetic improvement to increase productivity and rusticity of their colonies. The biological particularities of the domestic bee polyandry and haplo-diploïdy) and the complexity of economically important apiculture traits (expressed by thousand of wxorkers and their queen within a colony) makes the development of efficient selection plans difficult in comparison with classical wild species. The impact of polyandry on the evolution of cross-breeding and conony performances was evaluated using stochastic simulation.

The efficacity of a selection program is based on many parameters depending in part on the biological constraints of the species and the means available to the breeder. Approximately ten days after emerging, the young queens leave their colonies to mate during several mating flights with 12 to 16 haploid drones. She then stores the sperm collected for the rest of her life. To control reproduction, the queens and drones are isolated in mating stations or artificial insemination is practiced. This method makes monoandry possible by insemination with ony one male. The drones, since they are haploid, produce identical gametes and the colonies produced are genetically homogenous. By modeling the individual genetic values of the queens, drones, groups of workers and complex phenotypes that result at the colony's scale, we explored the effects of monoandry vs polyandry on the evolution of performances and inbreeding. Two selection strategies were considered (mass vs maternal within-family selection) along with other diverse genetic parameters, notably the genetic correlation between direct effects (effect of workers) and maternal effects (effect of the queen on the colony's performance). The results show that a selection program that would use insemination on only one male for 20 years would increase inbreeding rate by 50% as compared to a polyandry scheme without significantly improving performances. In fact, monoandry favors the genetic improvement of direct effects to the detriment of maternal effects.

Contact :

• Tristan Kistler (tristan.kistler@inrae.fr)
• Florence Phocas (florence.phocas@inrae.fr)