2.1. Test Organisms

Twenty inseminated queens, originated from the same mother-queen and inseminated with the semen of drones from the same father-queen colony, were individually introduced into 20 queenless colonies. After checking egg-laying, 10 mothers were randomly selected and kept in isolators with empty Dadant combs. Each mother was kept in one insulator (n = 10, 435 × 300 mm). Isolators with the bee frames were placed in a bee family of Apis mellifera carnica (Pollmann, 1879), in which bee mothers were placed for 12 h. After 24 h of egg-laying, the queens were released, and isolators containing combs with eggs were left within the colonies for further worker-brood rearing. On the 19th day of apian development, the combs with the already sealed worker brood were transferred to the incubator (temperature of 34.4 °C ± 0.5 °C and relative humidity of 70% ± 5%) in which they were maintained within individual chambers for 1 day old bees workers to emerge. The research material consisted of 2 day old honeybee workers.