Hygienic Testing Your Honey Bees

Where we are at now:

Over the past 10 years, hygienic testing of honey bees have revealed that the average bees across the country have increased resistance to varroa mites. This may be due to better breeding efforts on the part of the bee industry, and also the natural selection process at work in feral colonies.

Many are working hard to speed up the hygienic selection process of the honey bee. Mites have been a major problem for over twenty years now. And the faster we get to a point where bees can survive without chemical and non-chemical treatments, and survive on their own without beekeeper assistance, the better for all. Some have been keeping bees without traditional mite treatments for many years now. But losing an acceptable winter loss is probably built into their operation. Hopefully one day, no losses due to varroa mites will the norm for all beekeepers.

Freeze killed brood hygienic testing:

This hygienic test involves freezing a portion of comb (approx. 100-150 cells) taken from the hive and placed into a freezer. Freeze the comb for 24 hours. Then you replace the comb back into the comb "hole" you created when you cut out the comb. Most indicate a 48 hour testing time in determining the hygienic behavior of your bees. Previous testing has set the standard of 95% of the previously frozen cells being cleaned out for a good hygienic colony.

Using liquid nitrogen:

This hygienic test involves the same procedure as the comb freeze method but instead of cutting out the comb section, you use a three inch cylinder pushed into the comb, then pour liquid nitrogen onto the comb, freezing the brood. You must be certain to use enough liquid nitrogen to kill the brood. After replacing the frame back in the hive and waiting 48 hours, you then would count the number of cells removed from the three inch circle. 95% is the standard for a good hygienic hive. You can do a simple internet search for detailed past testing and full procedures on liquid nitrogen testing.

Other Considerations:

Many beekeepers are not going to buy liquid nitrogen or take the time to cut chunks of comb out of their frames. And for the backyard beekeeper with a few hives and just wanting to raise a few queens, the following are a few suggestions that make selecting the best queen you have, still possible. They may not focus on the same genetic traits the bees display in the comb freeze and liquid nitrogen tests, but help select bees that still use effective means to survive.

Paper Towel Testing:

Years ago, when we were playing with around with FGMO (Food Grade Mineral Oil) for mite control, the protocol called for soaking cotton cords in FGMO and placing them on the top of the frames. We observed three distinct reactions from different hives. 1) The bees would ignore the cords. 2) The bees would coat the cords with propolis. 3) The bees would shred the cotton cords, drag them through the hive, and shove them outside the front door. We do not use FGMO fogging (or the cords) after our initial testing of the claims, but have continued to use our experience in our queen evaluation procedures. What we do now is soak paper towels (They do not have to be dripping wet) in Canola oil (shown to have certain qualities and benefits to bees) that has some menthol or thymol crystals dissolves in the liquid. We place one paper towel on the top of the frame (middle of the brood chamber) in each colony being tested, and wait 24 hours. We want bees that exhibit the traits displayed (as in #3 mentioned above) by the removal of the paper towel as soon as possible.

Beekeepers also can evaluate their hives on many other factors that affect hive health. Every spring we have queen evaluation days. This is a time that local beekeepers assist in helping us select breeders for the coming season. Part of the criteria we look at in selecting queens for further consideration such items as:

Mite counts. Mite counts are an "after the fact" indication of hygienic and other desired traits that you should seek for your bees. Colonies that have good grooming, hygienic traits, and overall strong genetics, have few mites and can cope with mite pressure and other issues.

One mite count alone, means nothing. It is a snapshot of the varroa mite level for a very particular period of time. Many factors affect mites counts. The best use of mite counts is when you can use multiple counts at intervals such as every two weeks, to get a broader idea of what is happening in the hive. Is the mite counts trending higher, lower, or staying the same? Only then can you see how your bees are dealing with mites, and take additional steps of your IPM plan.

Clean bottom boards. We want bees who display good housekeeping traits. Indications such as a very clean bottom board, has positive qualities. While researchers have isolated genes being in control of specific behaviors of honey bees, good grooming bees are usually good house cleaners, and many good house cleaners are good at detecting infected mite larvae in the brood comb. You should seek bees to propagate that display as many of these traits as possible.   

No pests. We occasionally run across a colony while doing early spring queen evaluations with a wax moth larvae, moth, of even a small hive beetle running around. This automatically disqualifies a queen for consideration for breeder selection.

Even if you have just a handful of colonies, yet want to raise a few queens, selecting from your best colonies and genetics is in your best interest and benefits the honey bees. Too many beekeepers are still trying to save each and every hive through chemical treatments and other "band-aid" approaches. Some have commented that if we would have had no treatments to use on varroa mites from the very beginning, we would have been in a much better place today after building off the survivor stock.

We do not want to suggest you should let your bees die. Instead of waiting for colonies to die over winter, a much better approach would be replacing weak genetics with better queen stock, many times from your own operation. We must make efforts in building a better genetic pool and realize that there is a difference in genetics, breeding operations, and the ability of certain strains to handle mites and other disease.

Written by Mike Thomas, and may not be the view of all NSQBA members.