Natural Comb Management of Honey Bees for Varroa Control

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2007: $15,000.00
Projected End Date: 12/31/2009
Region: Southern
State: Tennessee
Principal Investigator:


  • Animals: bees


  • Crop Production: application rate management
  • Education and Training: demonstration

    Proposal summary:

    The parasitic mite, Varroa destructor is a serious threat to honey bee colonies. The southeast has a very strong beekeeping economy including honey production, bee package production, queen production, and pollination of many crops grown in the southeast and beyond. Southeastern beekeeping products and services are shipped throughout the United States. Varroa mites have caused massive loss of honey bee colonies and the need for miticide applications, often done twice a year. The economic impact of Varroa mites on beekeeping in the south has been great. Due to the need for pollination in many other agricultural pursuits, this economic impact is continually felt across the agriculture economy as pollination prices increase due to the increased cost of managing hives with Varroa mites. There have been many strategies developed to deal with Varroa destructor. After the initial spread of Varroa mites, which wiped out many beekeepers, miticides where developed to deal with them. Over time, however Varroa mites have become resistant to some of the chemicals used. In addition, the chemicals have been shown to contaminate the wax comb that they come in contact with, thereby creating a potential for honey contamination and toxin buildup which can affect queen viability. Organic miticides have been developed, but these too must be kept separate from honey supers, create a yearly expense, can potentially leave some residue in honey, and some are difficult to apply. Changes in management of honey bee colonies have been developed to deal with the mites also. “Drone comb trapping” traps and kills Varroa mites without pesticides, but it takes a very significant amount of labor that is unrealistic for most beekeepers. Queens have been developed with genetics that help the workers deal with the mites better, but their availability is limited, and there is an increase in management ensuring that all colonies remain headed by mite resistant queens. Genetic mite resistance is also inconsistent once these queens are put into commercial queen rearing protocols and open mated. A more immediate way to deal with Varroa mites without the application of pesticides, or significant increases in labor and expense is needed. Varroa mites reproduce inside the brood cells of honey bee colonies. The size of the cell and factors it changes may have an effect on the reproduction of the Varroa mites in bee hives. As a result, many beekeepers are moving towards using a foundation with smaller cell sizes. Foundation is what is used to get the bees started building their comb at a predetermined size. Small cell success may be attributed to reduced larvae capping, and brood emergence times. Varroa mites only invade brood cells during a short period at the end of the brood cycle, and mature just before emergence, so reducing these brood development times could reduce Varroa populations. One major problem for beekeepers wanting to move towards small cell foundation is that beekeepers often find honeybees do not easily accept the smaller sized foundation and build comb on it properly. Partially in response to difficult acceptance of small cell foundation, beekeepers have begun developing hives without the use of foundation to try and get “small cell bees”. There is some historical discussion and research that questions whether or not the current standard foundation cell size of 5.4mm is larger than what the bees would naturally build. In addition to affecting the cell size, raising bees without foundation creates other differences between conventional bee hives and “foundationless” bee hives. When bees are kept without foundation, much more of the hive is devoted to drone comb. Drone (male honey bees) cells are larger in size than worker cells, and the preference of Varroa towards drones is well documented. This additional amount of drone comb must have some effect on Varroa populations. Due to the reported success of beekeepers keeping bees without foundation, and without Varroa treatments, this effect may in fact be positive for the survival of colonies, in addition to the smaller worker cell sizes. Both established and new beekeepers often start new colonies with small colony splits where they add frames and boxes to build up to a standard, full size hive. In following years, drawn comb is often removed from the brood area to make additional splits for resale or expansion. If during this process, removing the use of foundation is found to be beneficial in dealing with the Varroa mites, it will reduce the costs of beekeeping by saving money on foundation and pesticides while also removing the possibility of contamination of honey, the beekeeper, and the environment by Varroa mite pesticides. Not using foundation creates the need for subtle management changes which we will also explore and document. For this experiment, we want to establish an easily reproduced protocol to develop bee hives without the influence of predetermined cell sizes on foundation. We additionally want to manage these colonies, mirroring the configuration of dissected feral honey bee colonies. This configuration consists of about 17% drone comb located on the outside edges of the colony, brood comb in the center of the colony, and honey storage above. In the 2nd year, we will continually remove frames, with larger cell sizes in the worker comb, brood nest area and replace them with empty frames for the bees to build more comb on. This will replicate the process some “natural cell” beekeepers use to get their bees to build small cell sizes. If observations on new foundationless hives are correct, these larger cell frames should be the older frames. The smaller cells are constructed after the bees have had more time without the influence of foundation. We can determine if this is true or not by marking the date on the frames. Beekeepers often mark the year on their frames to be able to determine the age of the comb and could use this as a guide for the “regression” process. A verbal report will be given at the Anderson County Beekeepers Association. A PowerPoint presentation will be developed for this purpose. The presentation will also be given at Roane/Morgan, Knox County, Blount County Beekeeping Association and a Crossville beekeeping group. We should be able to additionally address the Tennessee Beekeepers Association at their annual meeting. We will set up two study groups, at two different locations consisting of a total of 20 hives. Queens will be used from the same supplier. Each frame in all hives will be assigned a unique number. Group one will have 10 hives starting as 5 deep frame nucs made up from standard, 5.4mm comb hives, and be built up to “double deep” colonies. At another location, the 2nd group will have 10 hives started as 6 medium frame nucs from hives that where developed as foundationless hives the previous year. These will be built up to “3 medium” hives. Both groups will be developed over 2 years. The 2nd group, foundationless hives will have gone 3 years without the influence of foundation at the end of the 2nd year of the study. Five of these hives at each location will be the control groups and will use regular, 5.4mm sized wax foundation in frames added to the hives as they grow. In the 5 test hives at each location, added frames will be modified by removing the “wedge” and replacing it perpendicular to the top bar and coating it with wax. This will create a wooden “starter strip”. This encourages the bees to build comb in alignment with the frames. When frames have been added and the hive is built up with additional comb, the original frames of the nuc will be removed and replaced with, foundationless frames. The control hives will also have the original nuc frames removed, but replaced with new wax foundation frames. Once built up, the foundationless hives will be manipulated by removing each frame and identifying them as either “worker comb”, “drone comb”, or “honey storage comb”. Percentages of each will be calculated. All combs will be digitally photographed with a metric ruler placed across the comb on each side. Cell diameter will be measured, and averaged. These hives will be organized with about %17 drone comb on the sides, honey storage comb on top and worker comb in the middle brood nest area. This process will be mimicked in the control hives. In the second year, foundationless hives will have the largest cell sizes in the brood nest area removed and replaced with empty foundationless frames. This will give the bees the opportunity to develop more combs without the influence of foundation and should get even smaller cells. This will be mimicked in the control hives. Foundationless comb built in the second year will be measured as stated above. Each year, average “24hr mite drop counts” will be done on all hives to determine the level of infestation. This will be done with sticky boards that are placed under the hive's screened bottom boards. After a period of 3 days the tray will be removed and the mites counted to find 24hr average. This will be done 10 times from June through October to get an idea of trends in mite levels. Hive inspection notes will also help determine infestation levels.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.