Observations of the ectoparasitic bee mite Varroa destructor in honey bee (Apis mellifera) cells infected with chalkbrood (Ascosphaera apis)
Diana Sammataro and Jennifer Finley
28 to 30
We have observed an interesting phenomenon: the survival of varroa on mummified larvae infected with the fungus Ascosphaera apis. In the summer of 2003 we conducted a varroa study where frames of drone foundation were shipped to eight co-operators in six US states (AZ, CA, FL, ME, MI, ND). The frames were placed in colonies highly infested with varroa until the foundation was drawn and eggs were laid. Once the drone larvae were capped (time varied depending on the co-operator) the frames were shipped to our lab via overnight courier. When we received the frames, they were immediately placed in an incubator (29.4 °C, 80% RH). We collected varroa from these frames within 2 days by pulling out all the brood from the frames with forceps and harvesting the mites off the larvae/pupae with slim probes. By the middle of the summer, we observed that on some frames 25 to 50% of the brood cells showed symptoms of chalkbrood disease and in those cells varroa was living. As we were looking only for mites and not the fungus, we neither recorded nor had any prior information on the chalkbrood levels in these colonies. Chalkbrood was identified by visual observation of the mummified remains of the brood in the cells.