1. Landratsamt Heidenheim Veterinärwesen und Verbraucherschutz, Heidenheim, Germany
2. Wageningen Plant Research, Wageningen University and Research, Wageningen, AA, Netherlands
3. Honey Bee Research and Extension Laboratory, Entomology and Nematology Department, University of Florida, Gainesville, FL, USA
4. National Reference Laboratory for Bee Diseases, Friedrich-loeffler-institut (FLI), Federal Research Institute for Animal Health, Greifswald, Insel-Riems, Germany