Response of Apis mellifera L colonies infested with Varroa jacobsoni Oud

The response of A mellifera colonies to Varroa-infested brood cells has been investigated. Using special combs which guaranteed that the structure of the cell cap remained undamaged in the process of infestation, we infested worker brood cells with 1 or 2 mites each. The artificially infested cells were detected, uncapped and removed to various degrees by the worker bees of different carnica strains. Brood cells infested with 1 mite were removed from 5.5% (min) up to 95.8% (max) those with 2 Varroa from 4.8% (min) up to 100% (max) till 10 d after infestation. Figure 1 shows the means of the removed brood cells infested with one mite. The removal rates of the 2 infestation levels differed (P ≤ 0.01). Those colonies with a high removal response to brood cells infested with 1 mite also showed a high removal response to brood cells infested with two mites and vice versa (r = 0.76; P ≤ 0.001). Varroa mites escaped or were possibly killed. The signals which cause the removal are unknown. We do not know to what extent the method influences the magnitude of the removal behavior