February 2025 BIBBA Monthly

Key takeaways – and hard truths

• Varroa resistance is a stable trait in local bees. It appears to be a dormant ability controlled by epigentics. (Treatment-free practitioners realised this several years ago, but now it’s been confirmed by scientists.)
• It’s a strongly conserved trait. Martin et al have discovered it’s inherited down the queen line. (Ron Hoskins told me this around 2015-2016, but never documented it.)
• Varroa resistance is primarily due to the uncapping-recapping trait. This is new work by Riley, Martin and a few others and in my opinion, the only genuinely novel and significant advance in varroa control in the last 30 years. It is straightforward to monitor how much this is expressed in colonies by regularly examining the debris under a mesh floor (Steve’s book and the website varroaresistant.uk explain how – tracking mite drop rates and examining other clues), then propagate from the colonies which express it most strongly, e.g. requeen colonies with many mites, with queens from these.
• Paradigm shift: Steve Riley & Stephen Martin methodically tracked mite levels in a colony and found brood breaks and grooming seemed to have less impact than previously thought, and hygiene and mite biting may even have zero impact on overall mite levels. However, sometimes these traits overlap uncapping-recapping and some create similar debris, so we (and I include myself here) have been misattributing why some colonies have low mite levels!
• This means beekeepers finally have a straightforward, reliable way to select for mite resistant bees, in a way similar to their existing practises, because uncapping-recapping is a straightforward thing to spot and select. This is why it’s attracting so much attention as a path to treatment-free.
• The speakers advocating conventional breeding/selection techniques cautioned that it takes 3-5 years. However, an awkward fact: After going completely, full-on treatment-free I just used swarms from free living colonies to populate my hives, and within 2 years the mite drops were so low that when the speakers said “less than 5 a day is acceptable” I thought that sounded very high. And I used no directed selection at all, just “black box beekeeping”, simply letting the failing colonies die. This could be because I was only selecting for survival, not honey yield or temperament. It could be I started with better genetics. But I’m not the only one who has found 2 years to get effectively no varroa, so it strongly implies that directed breeding hinders, rather than helps, bees developing varroa resistance…!
• Repeatedly importing queens to an area dilutes useful traits and delays re-establishing the widespread, but dormant, mite resistance traits.
• The BBKA is beginning to update its training to include information about hygienic traits in its advanced courses (new syllabus due Nov 2025).
• About 25% of UK beeks now have at least some TF colonies. Winter losses seem to only be 5% higher than for colonies treated with miticides.
• You can tell if your bees are expressing VSH or just “normal” hygienic behaviour by the appearance of the ejected pupae:
  • Normal anti-disease hygiene results in bees throwing out dead / dying larvae which are discoloured and/or “melted” looking.
  • If the larvae (or the dismembered parts of them) are a healthy white and clearly segmented, it’s Varroa Sensitive Hygiene (VSH) like uncapping-recapping. Specialist bees are targeting the smell of the varroa damage (octopamine), not the smell of death.
• With VSH, “Sniffer” bees which are particularly sensitive to the scent of octopamine remove caps of suspect cells. Then “Remover” bees, which are a bit less sensitive to octopamine, can smell it and remove the infested pupa, interrupting the varroa breeding cycle. Finally “Recapper” bees, least sensitive to octopamine rebuild the cap.

The day was packed with interesting stuff. We heard how “bite marks” on varroa turn out to actually be dents in the carapace from birth deformities; how the American method of alcohol washes to estimate mite numbers is potentially misleading; and how Bald Brood is actually a good thing to see, as a patch of uncapped cells indicates hygienic or VSH behaviour (a line of uncapped cells indicates wax moth damage).

Throughout, the speakers acknowledged research by others such as Grindrod, Oddie et alia, and several name-checked Ron Hoskins as the godfather of resistant bees in the UK. Ron would have loved knowing his work was now canon! I was sitting next to several people from Reading BKA who had been trained by Ron and they were very moved by this.

I recommend you look at varroaresistant.uk to learn more details about uncapping-recapping.

There were also a lot of fascinating people among the attendees. Some I already knew, or had heard of. Others had interesting stories like “I had medical issues and couldn’t open my hives for 18 months, I noticed they were fine”. Great crowd!

Thanks to Karl Colyer for the heavy lifting of organising this complex event, and the local Stratford Bee Keeping Association for the calm, quiet background running of the event – many tasks from car park stewards to prepping vast amounts of cake.

By Paul Honigmann [author of The Observant Beekeeper]

Original Article - Varroa Resistance and Treatment Free becoming mainstream | Oxfordshire Natural Beekeeping Group