>Furthermore, they mention that AHB populations in Brazil had higher levels
of infestation in cooler regions.

To add just a bit more to the post made by Peter Borst–here is a quote from
the Morse/Flottum book: Honey Bee Pests Predators & Diseases (p. 298):

“...the infestation level of bee colonies in a cool climate at an altitude
of 1,400 meters was as much as 10 times as high as that of colonies kept in
a warmer region at 300 meters above sea level, even though the two
locations were within 150 km of each other and the colonies were headed by
sister queens.”

I can say also that varroa is unfortunately alive and well in Alaska. The
only AHB in Alaska is the Alaskanized Honey Bee that some of us are hoping
will develop. So far, it hasn’t been a stellar success.

Regards,
Dick