Another study from the Nordic countries, besides Gotland research, that grooming or VSH plays play no role in varroa resistance when natural selection has been used. This study also ruled our brood volatiles as the explaining factor by putting only susceptible brood in the tested colonies.
Beekeeper in Ostlandet Norway has been treatment free since 1997, 19 years. In the beginning big losses, but last 10 years losses below region average.
Peter Neumann is propably the most respected bee researcher in Europe.