Earlier in the week I was going to post something to the effect that Australia has nothing to worry about. Much as the media loves a good terror story, the recent incursion of two V. jacobsonii on a small hive of Apis cerena in Townsville, Queensland is less scary than many other close calls we've had over the past decade - for instance, in 2012 when biosecurity caught a hive in the port of Sydney with 150 V. destructor on it, or last year when the Varroa-resistant queens we started importing had V. destructor on their attendants. After all, V. jacobsonii doesn't parasitise European honey bees, does it? That was part of the reason for differentiating jacobsonii from destructor sixteen years ago (Anderson 2000; Anderson & Trueman 2000).
Except that in 2008 some researchers in P.N.G. found out that V. jacobsonii had successfully "jumped" species from Apis cerena to A. mellifera (Roberts, Anderson, and Tay 2015). The impact on A. mellifera is still unknown, but probably not good. The sub-population of V. jacobsonii that made the jump actually underwent a pretty significant speciation event, and are now unable to breed on A. cerena (which thankfully means, though basic logical inference, that the ones in Townsville can't be the infectious ones). They published their results in 2015 in the journal of Molecular Ecology, but a lot of people (myself included) didn't hear about it because it's hard to get a copy of the article without paying for it unless you work in a university. How this basically went under the radar in Australia just goes to show that there needs to be more communication between scientists and people working in the industry. I realize that the government leans on the side of caution when it comes to biosecurity, and I think that's smart, but I wish they had been more specific about why they were being cautious in this case.
Apis cerena swarms much more readily than A. mellifera. Until we know more about the specific genetics of the jacobsonii mites found I (sort of) understand why everyone at biosecurity is on tenterhooks.
The fact that the hive in Townsville was landside and more than two years old is a justifiable worry. If the hive did swarm, and it was carrying varroa, then we may have had varroa on the continent for over a year already. The upshot is that - like the mites in PNG - it may take these mites another 30 years to evolve a subgroup capable of moving into our commercial bees.
Anderson DL (2000) Variation in the parasitic bee mite Varroa jacobsoni Oud. Apidologie, 31, 281–292.
Anderson DL, Trueman JWH (2000) Varroa jacobsoni (Acari: Varroidae) is more than one species. Experimental and Applied Acarology, 24, 165–189.
Roberts JMK, Anderson DL, Tay WT (2015) Multiple host shifts by the emerging honeybee parasite,Varroa jacobsoni. Molecular Ecology, 24, 2379–2391.