Project Scope Varroa Infestation Measuring Methods (VIMM)
Project Target Establish and improve methods to determine the Varroa infestation level in a colony.
Current Status, Assumptions and Proposed solution
– Problem definition
– Current solutions
– Expected future solutions, trends.
– Proposed solution
To determine the level of Varroa resistance of a colony, it is of major importance that one can measure the amount of Varroa in the colony (infestation level). Most of the current techniques are laborious or give variable results. There can be different objectives for measuring the Varroa level:
– Determine optimal timing for – mite treatment.
– Determine treatment effectiveness.
– Determine the growth of the Varroa in the colony over time (as an indication of Varroa resistance).
– Determine the level of Varroa resistance of a specific trait (like removal of Varroa infested brood).
Methods can be either tailored for use by institutions or beekeepers or both.Currently, the most used methods are:
– Counting the dead mites on the bottom-board over time (beekeeper, institute).
– Counting the mites on a sample of bees by washing or using sugar powder (beekeeper, institute)
– Determining the amount of fertile an infertile mites in brood (institute).
– Determining the level of brood removal of brood introduced in a colony from another highly Varroa infested colony by opening 200 cells just after capping and 200 other cells one week later (institute).
The first two methods require repeated measurements if one needs to get a measurement of the level of Varroa resistance and will need a large part of a season to make a final judgment. The third and fourth methods give a quicker assessment but need special training and maintenance of highly infested colonies for the brood removal method.Arista Bee Research will focus its selection program on the brood-removal trait of resistant honey bees for which the 3rd and 4th methods would be the default methods of choice. These methods have proven valuable while establishing and monitoring the Varroa Sensitive Hygiene (VSH) line at the USDA in Baton Rouge, Louisiana, USA. However, these methods need a large amount of labor and rely on a continued stream of high-infested colonies. The amount of labor and infested colonies is the biggest bottleneck in a breeding program with a planned selection of hundreds of queens.The described methods will be established in the new foundation to ensure that the other projects can be supported and that promising leads can be investigated. Arista Bee Research will work with its partners to get these methods in place and where possible improved. In addition, to ensure that a large amount of queens can be tested, research will be started to develop a new method which will permit easier assessments of large numbers of colonies.As a first lead we will investigate is the use of Computerized Tomography (CT) Scanning. Ideally we would be able to scan frames with recently capped brood and measure the Varroa infestation without opening or damaging the cells. If it is possible to locate the infested cells by this CT scanning, these cells could be investigated again a week later and it would then be possible to establish possible removal of each of the mites/pupae. As this would be a paired observation, a relative low infestation level would be sufficient (e.g., 2-3% of 500-1000 cells, compared to 10-20% in 200 cells). Because this would not require highly infested colonies (the major bottleneck), a large number of colonies could be tested with very reliable results.
Science & Technology
– Target Technology: available, required
– Approach, Methodology, Tools
CT-scanning was developed for diagnosing human health. The development of very fast and affordable computerized systems has also enabled the development of smaller scanners for R&D purposes at acceptable price levels. One of the latest models has been acquired by Wageningen University (one of the partners) and can be rented by Arista Bee Research. Given the size of the scanner, relatively small frames will be used (Mini-plus, 16×22 cm). In a pilot test we will investigate whether we can “visualize” Varroa mites in the brood and will establish the accuracy by validating the scan results by manual inspection of individual brood cells. A next step would be the automation and interpretation of the scan results to determine which cells are Varroa infested. This will be mainly software development.
In addition we will have to validate/establish the minimum infestation level at which we get reliable results as there might be a threshold infestation level at which the bees will remove the infested cells.
Project Evaluation
– Potential value
– Probability of success
Any method which can speed up or improve the assessment of queens/colonies for Varroa resistance is of very high value in any breeding-selection program – if not the major key. The proposed CT-technology itself is very well established, available in Wageningen and is not a risk for the project. However, this particular biological application has to be proven. The resolution of the CT-scanner used is around 0.1 mm. A mite is around 1 mm broad and <0.5 mm high. So the size of the mite, having a similar density as a bee, is on the border of detection. We will need to use the 3D features of CT-scanning to maximize the resolution and the probability of detection. We judge the probability of success as medium (3 on a scale of 5). Combined with the high potential value (5 on a scale of 5), this project becomes a high priority project.
Project Planning & Resources
– Planning
– Resources & Partners
CT-scanning: The pilot phase of the CT part of the project has started and will take around a year to be completed. Project leader for this part of the project is Hans Middelbeek (0.2 FTE). He will cooperate with the Wageningen University for the scanningwork and with the software company Nspyre for developing software for automated interpretation of scan data (most likely Neural network based).

For establishment of the conventional methods, we have obtained and wintered untreated colonies in hives that have adapted bottom boards and Mini-plus frames.

Once funding becomes available, the overall project will be fully resourced with 2 FTE and is expected to run for at least 5 years. Partners for this project are: Wageningen University (CT-scanning), Kirchhain Institute (infested brood) and USDA-Baton Rouge (infested brood).