Behavioural overdominance of honeybee colonies kept simultaneously on standard-cell and small-cell combs

Overdominance is often observed in the case of intergenic interactions and is referred to as one of the major factors determining hybrid vigour or heterosis. Placing combs built on both a wax foundation with small cells (cell size of 4.9 mm) and a wax foundation with standard cells (cell size of 5.5 mm) in the brood chamber resulted in the emergence of the behavioural overdominance of such colonies. In order to investigate this phenomenon in terms of the use value of bee colonies kept simultaneously on two types of combs, they were compared to colonies kept exclusively on small-cell combs and to colonies kept exclusively on combs built on a standard-cell wax foundation. Increasing the variation in cell size in honey bee colony nests by placing both small-cell combs and standard-cell combs in it resulted in overdominance in terms of functional properties, i.e. an increase in the productivity of colonies. Therefore, modifying the inanimate element of the bee colony nest environment, specifically the comb, produced an outcome analogous to hybrid vigour or heterosis, which is the result of increased intraindividual genetic variation. In addition to polyandry, the different cell sizes in the combs, where colonies raise their workers, may be an additional factor in the nest environment that increases the phenotypic variation of workers, which may translate into a more effective division of labour expressed by better adaptation and higher productivity of bee colonies. The role of combs, which are a non-living element of the nest environment, in the functioning of the superorganism of a honey bee colony remains both poorly understood and underestimated.