Varroa Resistance Conference Nov 15
When I stopped treating the first colony for varroa 10 years ago, it was exciting to see how it would fare over the winter. No treatment, no drone brood removal. Equally exciting was the coming spring development. No negative surprises.
Every year, I stopped treating more colonies. Every coming winter was just as exciting. Usually, it was other colonies that did not survive rather than those that did not receive any varroa treatment. But winter losses remained around 10%. Barely 15% at most, 3% at least.
When I stopped treating completely five years ago, it felt a little exciting again to see what the statistics would be, and the losses were around 5%. When the last colonies had been treatment-free for three years, I relaxed.
In the last two years, I have only seen a couple of mites when looking at the drone brood between brood boxes. Individual colonies in apiaries closest to other types of bees have exhibited various problems, such as slightly virus-damaged wings. However, some colonies must be the worst in various respects and become candidates for having their queens replaced, for example, in terms of development, temperament, and honey harvest.
With the entire area dominated by gentle, varroa-resistant bee colonies, queen replacement is easy. The old queen is removed and the colony is given a mature queen cell, and the new queen is allowed to mate residing in the colony in its apiary.
I am confident in what I know about how our varroa resistant stock in Hallsberg works. I don’t get worried if I receive an odd report that a queen’s colony is not behaving as expected. Though I am interested in trying to find out why, in order to understand how the bees (and perhaps the beekeepers) have behaved.
One positive thing is that varroa resistance seems to become more strongly “embedded” in the genome the more years a colony has been treatment-free. Not just in the queen’s genome through different genetic ways as changes in nucleus DNA and in epigenetics, but also in the entire colony, which seems to be passed on in some way. This is probably due to the mixture of microbes (bacteria, viruses, fungi, etc.) that play a role in the immune system. All creatures have a mixture of microbes (called microbiome) that can be damaged, for example by antibiotics or, as in the case of bees, treatment chemicals. However, sometimes one feels compelled to use them anyway.
The immune system growing stronger, can manifest itself for example, in bee colonies showing a small natural decline in amount of mites, especially at the end of October (and no bees with damaged wings), even though there may be 10-30 treated colonies spread across several apiaries belonging to different beekeepers 500-1000 m away from your own, with only 5 colonies of yours, two of which are treated (an actual example). This gives hope for the possibility of most beekeepers starting up and establish treatment-free apiaries.
The safest way to start a treatment-free apiary, which many have the opportunity to do, is to buy 2-3 splits from an apiary that has been treatment-free for a couple of years, or almost as good, buy 2-3 queens from treatment-free bees.
The 2-3 colonies/splits should preferably be placed 2-3 km away from other bees and no other bee colonies in the becoming treatment free apiary. Keep track of the infestation rate using a shake jar (e.g., EasyCheck) in June-August. Natural downfall tests for example over 3 days, every 14 days/weekly from September until the end of October.
If the infestation rate exceeds 3% (9 mites/1 dl of bees, approx. 300), treatment with thymol can be recommended. Concerning natural downfall of mites in September-October, you want to see a reduction by the end of October.
The splits with the new queens are fed with sugar dough until winter to make them strong. And also colonies/splits with replaced queens. A apiary with only splits from untreated bees most likely does not need treatment. An apiary with replaced queens may need treatment, at least in the first year.
On November 15, 2025, we will hold our 7th annual treatment free conference in Hallsberg to share advice and experiences. Welcome!