EN
The study was aimed at investigating whether keeping colonies on small-cell combs (cell width of 4.93 mm), in combination with natural selection resulting from the lack of V. destructor treatment, leads to an intensification of hygienic behaviour. We also sought to determine whether the very transfer of colonies treated against V. destructor (without natural selection) onto small-cell combs causes an intensification of hygienic behaviour. Hygienic behaviour was monitored in both varroatosis-treated and untreated colonies kept on small-cell combs, as well as in two control groups consisting respectively of varroatosis-treated and untreated colonies kept on combs with standard size cells (cell width of 5.56 mm). Regardless of whether they had been treated or not, the colonies kept on the small-cell combs removed dead pupae (needle test) faster than the colonies kept on the standard-cell combs, both treated and untreated. In this way, we demonstrated that hygienic behaviour can be intensified by transferring colonies onto small-cell combs, even without natural survival selection resulting from the lack of treatment against V. destructor. The practical use of this method, however, requires further studies of various bee populations, as they may differ significantly in the intensity of hygienic behaviour and, possibly, in their aptitude for being kept on small-cell combs.