INVASION OF VARROA-JACOBSONI INTO DRONE BROOD CELLS OF THE HONEY-BEE, APIS-MELLIFERA

Invasion of Varroa mites into drone brood cells of honey bees was studied in colonies without worker brood. The probability for a mite to invade was dependent on the brood/bees ratio, which is defined as the number of drone brood cells capped per kg of bees. When compared with invasion in colonies with exclusively worker cells, Varroa mites invaded drone cells 11.6 times more frequently. This suggests that the biased distribution of mites over drone and worker cells in colonies with both types of brood cells results predominantly from the higher rate of invasion into a drone cell per se, when compared to that into a worker cell per se. Since the rate of invasion is high in drone cells, a trapping method using drone combs may be very effective in controlling the Varroa mite. When no other brood is present, 462 drone cells are estimated to be sufficient to trap 95% of the mites in a colony of 1 kg of bees.