Drs. David Peck, Steve Walsh and I are in the very final stages of finalizing a Varroa Action Plan (VAP) for Newfoundland and Labrador, which remains Varroa-free as you know.  As part of the VAP, we conducted a pathways analysis and risk assessment regarding the spread of Varroa across the province in the wake of an initial Varroa incursion.  The role of drones in the spread is of significant importance.

The scientific literature has a range of distances that drones will travel to DCAs, and the distances between apiaries at which drones and queens will mate. Here's some examples: “Drones can mate with queens from colonies up to 16.2 km away” (Currie 1987: 138). “It has been shown in the foregoing that some queens can mate with drones when their colonies are separated by 10.1 miles [16.2 km]” (Peer 1957: 109). Currie gets his distance figure from Peer.

For the south Peace River region of Alberta, Tibor Szabo reported the drones and queens mated at distances up to 20 km from drone colonies. However, matings at those distances were rare. “Successful matings at up to 10 km distance were common in our experiments. At greater distance cross-matings were very rare and probably would not happen in nature if drones are plentiful. Therefore isolation distances of 18-25 km used in our closed-population breeding programme…may be considered adequate” (1986: 231).

This one by Mortenson, et al., of course, is not about distances per se, but simply confirms infestations of Varroa on drones in congregation areas.

https://link.springer.com/article/10.1007%2Fs00436-018-6035-z?fbclid=IwAR1jjfucPqq6evs1RmHpWmwmyRjb1is0C-tktfEVKxXvO95GgO9wuK0f9z4

The 16.2 km re. mating distance reported by Peer must combine both drone and queen travel.  I don't know what the max distances for queen travel are.

BUT, if Szabo concluded that isolation distances 18-25 for breeding purposes are required, why would this not also apply to Varroa transmission (without direct human assistance) and the design of quarantine boundaries?

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