Varroa mites continue to plague beekeepers in BC resulting in colony losses, but groups like the Comox Valley Beekeepers Association continue to look for methods to reduce the mites. Previously effective methods like using chemicals such as Apivar are becoming less effective as the Varroa mites grow resistance. As part of their 2023/24 Bee BC project, the Comox Valley Beekeepers Association looked to alternative, non-chemical methods of reducing varroa mites and how they could share this information with BC beekeepers.

The association built upon their project from last year which introduced two biotechnical varroa control methods: Drone Brood Removal Method (with a split drone frame) and Varroa Trap Method (with a frame cage). This year they introduced two more Biotechnical Varroa Control Methods called Artificial Brood Break (with a queen cage) and Complete Brood Removal.

How do these found biotechnical methods work?

  1. Drone Brood Removal Method with a custom split drone frame. Using the split drone frame allows the continuous removal of mites via drone brood while returning the frozen and uncapped half combs for exchange, which minimizes any draw on the colonies resources. This method should be applied routinely during the breeding season and is, therefore, considered rather a best management practice than a Varroa control method based on integrated pest management thresholds. The practical experience is that the Drone Brood Removal Method can reduce the development of the Varroa mite population below the treatment threshold until later in the summer, when additional Varroa control methods can be applied.
  2. Varroa Trap Method with a special frame cage. This method combines the concepts of the complete brood removal technique with that of a brood break. The queen is separated for 27 days with the aid of a frame cage, whereby she can only lay eggs in the comb within the frame cage. This trap comb inside the frame cage will be exchanged three times and removed once the brood cells are capped, thereby trapping the mites. Studies show that it is possible to eliminate 90% of varroa mites without chemicals. No detrimental effects on the queen or colony performance are known to exist. The frame cage for this method can be built with queen excluder material or purchased commercially.
  3. Artificial Brood Break Method with a walk-through queen cage. This method prevents the queen completely from laying eggs. After 25 days at the latest, the colony is completely brood-free and can effectively be treated with Oxalic Acid. As a chemical-free alternative, a trap comb with brood that is ready to be capped can be used to remove the phoretic mites. Studies have shown that there is neither a higher queen mortality, nor a weakening of the hive. Already one month after the brood break, the hives have more brood than the control hives. The queen cages for this method are commercially available ‘walk-through cages’ with queen excluder size grids in which the worker bees can enter and leave the cage.
  4. Complete Brood Removal Method. This method eliminates all brood and the Varroa mites within the closed cells at once. The varroa mites left in the colony are the ones on the bees, so that a subsequent Oxalic Acid treatment will be very effective. Again, as a chemical-free alternative, a trap comb with brood that is ready to be capped can be used to remove the phoretic mites. Even so the complete brood removal seems to be a drastic intervention into the colony it is based on the natural separation of brood and bees during swarming. Experience has shown that this method is well tolerated by the colonies and that the bees compensate for the loss of brood very quickly.

Biotechnical control methods originate from Europe and have only recently been adopted in BC; as a result, there are few English guidelines on these methods available to BC beekeepers. Club members Sibylle Walkemeyer P.Ag., MSc.agr and Wolfram Wollenheit volunteered to translate and prepare English versions of the materials. The Bee Research Institute in Kirchhain, Germany has been developing these methods since the 80’s so with consent from the institute, Sibylle and Wolfram translated and adapted the materials for BC beekeepers.

With the new materials, the club created resources to share with beekeepers in the Comox Valley Region and across BC. Over the past year, the group created flyers and held workshops introducing the four methods to beekeepers. They hosted two workshops in January 2024 and had members from various bee clubs across the province join.

In addition to creating resources, the association acquired 25 medium and 25 deep frame cages through the Bee BC program. The cages are available to the association’s members to loan to try the non-chemical methods.

The Comox Valley Beekeepers Association’s project provides beekeepers in the surrounding area with resources they would not have had access to before. While Varroa mites continue to plague beekeepers, the work being done by the Association is a step in the right direction. For more information on these methods, visit the Comox Valley Beekeepers Associations website.