• John Mackay

Col Loss at a Glance…

UNDER THE MICROSCOPE BROUGHT TO YOU BY dnature

By John Mackay

By now, I hope everyone has had a chance to look at the new Colony Loss Survey results. No excuse, Landcare Research even produce the ‘at a glance’ infographic that gives the information in a nutshell. If you haven’t seen it, I’ll wait . . .

John Mackay.

https://www.mpi.govt.nz/dmsdocument/50224-2021-Colony-Loss-Survey-infographic

My thoughts for previous years have been losses have been “fairly static at around 10 percent”. And yes, if those words ‘fairly static’ convey a certain complacency then, guilty.

However, the latest results show a marked increase in colony losses this past year – up by 20%, from 11.6% to 13.6%.

Predicted losses varied around the country – from a low of less than 9% in lower North Island, up to almost 19% in middle North Island. In our work looking at bee viruses, nosemas and AFB, we have heard of major losses in many areas of the country and so we would expect these losses to be a minimum at best.

For the first time, losses due to varroa have been the major contributor, with varroa-related causes surging by 50% to 5.3%. Given that many of the queen issues reported may also be due to varroa (viral infection of the queen for example) then varroa may be responsible for over half the total losses. With the reports of beekeepers walking away from hives or unable to afford treatments in the current economic climate then perhaps these results aren’t surprising. Looking at the varroa-related data more closely however does show some interesting information:

- 4.4% of beekeepers did not treat at all.

Was this question missed on the survey? Or are these the beekeepers who could not afford to treat?

- 13% of beekeepers treated their hives with only Bayvarol (synthetic pyrethroid) – not a best practice exercise as it promotes the evolution of resistance in varroa (genetic changes in the varroa which lead to Bayvarol not working at all). And yes, while 10% of beekeepers treated with solely amitraz products and ~10% with oxalic acid and other products, resistance to these has not been reported elsewhere in the world.

- Given the inaccuracies in monitoring varroa levels with methods such as sticky boards (the varroa get removed by something looking for a snack), then it is fair to say that most beekeepers are not adequately monitoring varroa levels in their beehives (only 31% doing sugar shakes or alcohol washes).

Two reasons are usually given for monitoring – one is to indicate when levels are high enough to warrant treating (rather than calendar timing). However, often treatment time availability is governed by the need to get treatment off before collecting a crop (especially if using amitraz in Spring) or the desire to have treatments out before winter. Therefore, one might question the need to monitor before treatment, given that you’re probably treating anyway. However, to know if a treatment has worked to reduce varroa to appropriately low levels then monitoring after treatment should be performed as a best practice. For more on this, check out the Mite Monitor program from Martin Laas and Rae Butler covered in another article here.

So, should we be alarmed? The increase is sharp and varroa has become the major cause (if it wasn’t before). Perhaps more alarming is the lack of industry’s ability to mitigate these issues. We are reliant on hope: hope that scientists will be sufficiently interested in the issue to obtain their own funding to work on the area, perhaps hope as well that the economics of the industry improve and effective treatment becomes more commonplace. Unfortunately, hope tends not to make the most sustainable of business models.

John Mackay is a molecular biologist and the technical director of Gisborne-based lab dnature diagnostics and logistics, as well as a hobby beekeeper.


0 comments

Recent Posts

See All