Invasion ofVarroa jacobsonsinto honey bee brood cells: a matter of chance or choice?

Abstract

SUMMARYInvasion of Varroa jacobsoni into honey bee (Apis mellifera) brood cells was studied in three initially mite-free colonies. Frames with emerging worker brood, heavily infested with mites, were introduced into each colony and removed the next day. During the experiments ample worker brood was available for the mites to invade. Invasions into brood cells started immediately after the introduction of the mite-infested combs, showing that mites do not necessarily have to have a period on adult bees before invading a cell. However, as most mites stayed on the bees for several days or even several weeks, the average rate of invasion was rather low. In addition, replicate experiments in the three colonies showed much variation: 50% of the mites invaded brood cells within 2.0 days in the first replicate, within 8.3 days in the second replicate and within 4.3 days in the third replicate. Possible causes for the low and variable invasion rates are discussed.