Hi,
I donīt have the exact reference, but I read that Apis mellifera was
imported into Japan in the 1950īs or 60īs (I think); these bees were
infested by sharing flowers with Apis cerana, robbing, etc.
Both species even have similar ferhomones, so even mating is possible
between them, only that itīs an infertile mating.
Varroasis scape diagnosis for a time, and Apis mellifera bees were
exported from Japan, altogether with Varroa mite, and since then itīs
been spreading all over the world.