Possibility to change the body size in worker bees by a combination of small-cell and standard-cell combs in the same nest

Abstract

The aim of the study was to investigate the impact of the combination of the colony type (kept on small-cell or standard-cell combs) and the width of worker comb cells (small-cell or standard-cell combs) on the body weight and morphometric traits of worker bees. The values of morphometric parameters of worker bees changed within a substantially lower range than the width of their rearing cells. This indicates that the worker body size is relatively constant, and manipulation with the cell width is not a good method for modeling the body size of workers. The reduction in the thorax weight was proportional to the decrease in the comb cell width, and this part of the body proved to be most susceptible to weight reduction caused by the use of small-cell combs. The rearing of workers in small-cell combs in the colony kept on standard-cell combs resulted in an increase in the value of the fill factor (thorax width to cell width ratio). The relatively constant body size of workers in combination with the use of small-cell combs resulting in an increase in the fill factor may be one of the determinants of increased resistance of the insects to Varroa destructor. The values of the morphometric traits commonly used for identification of honeybee subspecies, i.e., the length of the fore wing, the sum of the widths of 3rd and 4thth tergites, and the proboscis length, were inconsiderably altered vs. the changes in the comb cell width, which confirms their high suitability for identification of honeybee subspecies.

Dead Brood of Apis mellifera Is Removed More Effectively from Small-Cell Combs Than from Standard-Cell Combs

“…The more efficient removal of dead brood from the SMCombs may have been caused by the higher concentration of pheromones inside the cells, i.e., in the air filling the space between the pupa and the cell walls, which enabled workers to better identify dead brood. The higher concentration of pheromones may be related to the fact that, despite the 8–12% smaller width of the small versus standard cells, the honeybee body does not decrease in proportion to the cell width, as the thorax width decreases only by 0.8–4.4% [ 28 , 37 , 38 ]. This results in tighter filling of the cell by the pupa, and thus the presence of a smaller volume of air in the free space between the pupa and the cell walls.…”

“…This results in tighter filling of the cell by the pupa, and thus the presence of a smaller volume of air in the free space between the pupa and the cell walls. The fill factor, i.e., the thorax width to cell width ratio, is a measure of cell filling by the pupa [ 28 , 37 , 38 ]. At a similar level of secretion, the smaller air volume inside small-width cells is characterized by a higher degree of saturation with pheromones.…”

“…The colonies were kept in Dadant Blatt hives. The Buckfast bee colonies kept in our apiary are very well adapted to living on small-cell combs [ 37 ], hence we used these bees in our experiment. Each colony was kept in one brood chamber with 10 frames (435mm × 300 mm) and two honey supers, each with 10 frames (435mm × 150 mm).…”

“…Each comb in which the brood was pierced was marked and, after young bees emerged, the cells with open brood were photographed in the centre of each comb quarter on one side of the comb. Next, in each quarter, the widths of 10 adjacent cells contacting with vertical side walls were measured [ 37 ].…”

“…However, it has been shown that keeping colonies on small-cell combs exerts a significant effect on the morphological traits and the biology of worker bees. This results in a decrease in the thorax weight, head width and height, thorax width and length, width and length of fore wings, and width of the 3rd and 4th tergites [ 28 , 37 , 38 ]; additionally, it contributes to a higher effectiveness of hygienic behaviour [ 25 ] and a higher rate of springtime colony development [ 33 ] as well as extension of the lifespan of workers [ 39 ].…”