I am Dr. Rogan Tokach the honey bee research and extension specialist at North Dakota State University. In this quarterly column, I will provide updates on what we are doing at the NDSU Honey Bee Lab, highlight lab members, or share interesting research findings from the honey bee world that might be relevant to North Dakota beekeepers.
For this quarter’s NDBA newsletter, I thought I would take the time to give a little information on what research projects we have lined up for the summer of 2026. Overall, the NDSU Honey Bee Lab will be conducting four different projects. Three projects will be focused on Varroa mites while the fourth will be focused on sunflowers. Bear with me since the names of these projects are still being workshopped, but below I have highlighted each project and our hopeful expected outcomes.
Project 1: Season long Varroa control beginning with splits in California
First, I would like to thank the North Dakota Department of Agriculture, your Honey Bee Promotional funds, and beekeepers on the grant review board for providing the funding for this project. This project is being conducted by my M.S. graduate student Catherine Crosier who some of you may have met from her BIP days in ND or at the NDBA meeting this past fall.
The goal of this project is to evaluate various Varroa mite treatments in an attempt to find what treatments are most effective for different North Dakota beekeepers at different times of the year. Additionally, this project has a resistant queen stock component incorporated into it. Overall, this project is being broken down into two separate parts which are detailed below.
Project 1 Part 1: Treating colonies as splits with queen cells
While it is likely not a surprise to many of you, most Varroa mite treatments are more effective when there is less capped brood in the colony. Because most of our treatments rely on contact to kill mites, having mites in the dispersal phase and not protected underneath a wax cell capping can significantly increase treatment effectiveness. However, finding a time with limited capped brood after almonds before colonies begin their normal decline in October is almost impossible. One area of possible exploitation though comes with splits using queen cells. Naturally, when making a split and using a queen cell, there is a slight lag time in capped brood area occurring as the original queen’s brood emerges while the new queen begins laying. This creates an optimal treatment window where there is limited capped brood in the colony and a majority of Varroa mites are in the dispersal phase. My colleague Dr. Dan Aurell at Auburn University published a paper last year detailing the efficacy of treating newly made splits using queen cells with various Varroa control products. The full paper detailing the results of all seven treatment groups can be found HERE, but, in summary, he found multiple treatment groups effectively controlled Varroa including Apivar 1.0 and HopGuard 3 put in at the time of the queen cell, an oxalic acid (OA) dribble 18 days after initial colony establishment, and an amitraz emulsified concentrate (Bovitraz) group given one treatment 30 days after initial colony establishment. Additionally, he found no differences in queen establishment between any of the treatment groups This is likely not news to some of you as I know treating new splits with Apivar 1.0 is a common practice in some commercial beekeeping operations.
Where our research comes in is looking to build off that previous work performing a similar trial testing new treatments on their impact on Varroa control and queen establishment while also factoring in a Varroa resistant queen genetics component. In partnership with a commercial beekeeper who runs from CA to ND, we established 250 nucleus colonies. Half of the colonies received a traditional queen cell from a commercial queen breeder while the other half received a cell grafted from a queen with known Varroa resistant traits. Colonies were further broken up into five different groups with 25 colonies per queen type (50 total) receiving treatments that include an untreated control, Apivar 2.0, VarroxSan, one pouch of Norroa (500 mL), and an OA dribble. For the Apivar 2.0, VarroxSan, and Norroa groups, all treatments were given at time of cell placement while the OA dribble group received their treatment 18 days after initial nucleus colony establishment. Colonies were recently reassessed in ND.
This project is being conducted in collaboration with Dr. Meghan Milbrath of Michigan State University and Dr. Katie Lee of University of Minnesota. With their assistance another trial with almost identical methods is being conducted looking at an alternative commercial beekeeping pollination route from GA to MI. In this trial, colonies were split into single deeps rather than nucleus colonies giving further information on the impact these treatments might have on Varroa infestations and queen establishment in various conditions.
Project 1 Part 2: Management during honey production into fall clean-up
Managing for Varroa during the summer has become an arduous task for beekeepers. Because of the increases in amitraz resistant Varroa mites seen within some operations, it is becoming increasingly difficult to significantly drop Varroa infestations later in the year. Most research shows it is much more manageable to keep Varroa infestations low throughout the year rather than trying to drop them prior to overwintering. However, there remains questions as to the most effective treatment to use during this time which is further complicated by the fact that honey is a consumable product thus limiting treatment options when supers are on.
The second portion of this trial using the same, preestablished colonies as Part 1 looks to evaluate three different products for their effectiveness on controlling Varroa mite infestations and their impact on honey production when colonies are treated in June when supers are added. One treatment to be tested is Varroa Destructor, an extended-release OA treatment out of Canada. Meanwhile, previously conducted research in ND is being analyzed and commercial beekeepers are being consulted to determine what other two treatments are of interest. After honey production, colonies will again be assessed, and three final treatments will be implemented to assist in comparing what treatments help provide the cleanest honey bees going into the overwintering period.
Project 2: Evaluating new treatments against Varroa during honey production in ND
Similar to Project 1 Part 2, this project will evaluate different Varroa treatments during the honey production season in ND. This project will also be led by Catherine, and we are thankful for the support of the California State Beekeepers Association for providing funding to conduct this work. Again, in partnership with another commercial beekeeper, we will look to evaluate the impact of different Varroa mite treatments during honey production on Varroa infestation. Treatments for this trial include Varroa Destructor (the extended-release OA product from Canada), VarroxSan (extended-release OA), MBG-2X5G (a new L-glutamic acid based product from Mite-Bee-Gone), and an off-label extended-release OA treatment with a surfactant using SplillTech pads. Treatments will be implemented prior to supers being added and colonies will be monitored multiple times during the honey production season. The trial will conclude after honey is pulled when beekeepers would perform their typical fall management. This project is being performed in conjunction with Dr. Elina Niño at UC Davis to assist in future registration of these products in CA, and to provide additional information regarding what weather conditions they perform best under.
Project 3: Assessing Norroa pre-almonds through honey production
As previously mentioned, it can be difficult to keep Varroa mite infestations in check after almond pollination in CA through the honey production season in ND. A new, promising mite treatment called Norroa is hopefully able to provide a solution to this issue. Norroa is delivered to colonies as a sugar feed in pouches. This sugar feed contains double stranded RNA (dsRNA) that perform RNAi or RNA interference. In short, Norroa works when honey bees consume the sugar syrup. The dsRNA in the sugar feed is then transported to the brood food when it is produced by the nurse bees which the Varroa mite submerges itself in prior to its reproduction during honey bee pupation. The mite uptakes these dsRNAs resulting in RNAi very similar to how human bodies combat a virus. Overall, the mite’s reproduction is stopped, but the mite does not die. This is important to note because Norroa only suppresses mite reproduction, it does not actually kill mites in the dispersal phase meaning it should only be used during times of low mite infestation.
One of the times of low mite infestation when Norroa could be applied is when colonies are coming out of sheds. Project 3 involves assessing Varroa mite infestation from January through honey production in August in colonies treated with one of three treatments. Once again in partnership with a commercial beekeeper, treatments of Norroa (4 pouches and 2 L total), Apivar 2.0, and VarroxSan were put into double deep colonies recently removed from sheds in late January. Colonies were reassessed in mid-March. Colonies were assessed again and retreated with the same three treatments in May before supers will be added in June. Lastly, colonies will receive a final assessment after supers are removed in August. Overall, impact on Varroa infestation, colony strength and honey production will all be evaluated to determine if Norroa or another treatment from this study are viable for long-term use from January throughout the majority of the beekeeping season.
Project 4: Understanding impacts of colonies near sunflowers
When I made some rounds last summer meeting with beekeepers, a somewhat consistent thing I heard was that colonies no longer performed well near sunflower fields. While not every beekeeper reported this as an issue, a somewhat consistent theme emerged with multiple beekeepers relaying a similar story. Some commonalities that I heard were as follows. In the past, commercial beekeepers actively sought out sunflower fields since they provided a beneficial late season source of pollen and nectar; however, about ten years ago, some beekeepers noticed seeing a decline in sunflower honey production, and in the past five years, that decline has escalated to colonies near sunflower fields having a higher percentage of mortality compared to others within their operation. Colony losses in apiaries near sunflowers have now reached the point that some beekeeping operations are actively avoiding or moving away from sunflowers, a beekeeping practice that would have been unheard of just one decade ago. While many believe pesticides to be an issue, there is no singular consensus as to the causes of these issues near sunflowers as there could be multiple contributing factors.
This summer, a pilot study will be conducted in partnership with a commercial beekeeper looking at multiple colony metrics to further understand what may be causing these colony issues near sunflowers. This project, being led by my other M.S. student Kylie Mac Ewen, will follow colonies in apiaries either near sunflower fields or in apiaries without a sunflower field within normal honey bee flight distance. Colonies will be assessed pre- during and post-sunflower bloom for Varroa infestation and colony strength. Additionally, pollen will be collected during these time points and sent to our collaborator Dr. Pierre Lau at the USDA in Stoneville, MS. There, Pierre will break down pollen by type and analyze it for nutritional value as well as heavy metal content, both metrics that sunflower pollen has historically been known to be poor in. Lastly, pollen collected during those time points will also be sent to a lab for pesticide analysis to see what pesticides may have impacted colony performance. In total, this project will look to identify primary differences between colonies from the different sites allowing for an opportunity in future years to perform projects looking to alleviate some of the stressors sunflowers may inflict on colonies in nearby apiaries.
Overall
In summation, we have four exciting, applied honey bee research projects designed at providing answers to issues beekeepers in North Dakota are dealing with. The first three projects focus on evaluating several different Varroa mite products and treatment strategies at various timepoints to understand what, when, and how treatments can be most effectively applied. Meanwhile, our fourth project looks to take the first steps in understanding what may be the causes of poor performance for colonies near sunflowers providing us with a hopeful building block to address the issues with future work.
If you have any questions about our upcoming work, please feel free to reach out. I also hope to see many ND beekeepers at the joint NDBA meeting in Fargo this July where we will provide a further update on these projects and let you know what our preliminary results are. I hope your beekeeping season is off to a great start, and safe travels to all your colonies coming into the state!
Rogan Tokach
Assistant Professor
North Dakota State University
(701) 231-5761
rogan.tokach@ndsu.edu