Brood removal or queen caging combined with oxalic acid treatment to control varroa mites (Varroa destructor) in honey bee colonies (Apis mellifera)

Few studies of honey bee colonies exist where varroa mite control is achieved by integrating broodless conditions, through either total brood removal or queen caging, in combination with oxalic acid (OA) applications. We observed significant varroa mortality after total brood removal or caging the queens and OA applications in broodless colonies, as well as in colonies with brood that received four consecutive OA applications. In laboratory tests, we recorded higher mortality of caged bees exposed to Apistan® compared to oxalic acid or untreated control bees. However, this mortality is not believed to negatively impact the colony. We therefore recommend combining OA applications with artificial broodless colony conditions achieved either by brood removal or queen caging as an effective management strategy for varroa mites.