Damaged Varroa mites in the debris of honey bee (Apis mellifera L) colonies with and without hatching brood

The proportion of damaged Varroa mites within the debris of honey bee colonies is dis cussed as a possible tolerance factor of the host. We investigated the rate of damaged Varroa females in honey bee colonies with and without hatching brood. Additionally, in some colonies sealed brood combs were treated by the use of heat or formic acid to kill the mites within the brood cells to quantify the behaviour of the bees towards dead mites. In 17 experimental honey bee colonies (Apis mellifera) at two different study sites, the debris was checked at 12-h intervals. Nearly 5000 mites were individually analyzed for three different types of damages. The percentage of damaged mites varied on average from 44 to 63% depending on experimental conditions. No significant differences in the damage rates of 'phoretic mites' and 'brood mites' could be found. Dead mites from the treated brood combs were damaged to a slightly lesser extent. The significance of these results for the use of the parameter 'damaged mites' in selection programs is discussed.