Testing for diseases & parasites is a vast topic: we encourage you to take a class or come to a mentor workshop covering this subject.
There's controversy among beekeepers about treating for diseases and parasites. Some prefer to treat to try to save weakened colonies; others, concerned that mites or bacteria may become resistant to treatment, prefer to let only the strongest bees survive to propagate. You will have to make your own decision about what to do with your colonies.
Whichever approach to treatment you choose, you will be wise to test so that you know what is going on in your colonies. Then you can decide how to address a disease or parasite situation.
For Dan Maughan's slideshow at our August 12 2015 meeting, click here; for the Honey Bee Health Coalition's interactive guide on Varroa management, click here; for BeeInformed Partnership's guide to using oxalic acid for mite control, click here. Finally, to visit our Bees in the News Varroa research page, click here.)
Varroa Testing Methods:
Slider boards sprayed with cooking oil, inserted into screened bottom boards, will hold Varroa mites so that you can count them. Over 100 mites on a bottom board after a 2-day natural "drop" test shows that the hive has a significant Varroa problem.
Alcohol roll: A handful of bees can be swept into a tub or jar with an inch of isopropyl alcohol. This will knock mites off the bees, killing them; however, it will also kill the bees. Many prefer a sugar shake in the jar: see images at right. The HBHC guide, linked above, gives more details on how to do this.
Another testing method favored by many organic beekeepers is the powdered sugar dusting: the powdered sugar makes it hard for mites' hooked claws to hang onto the bees, & as the sugar promotes bees' grooming each other, they knock down many mites. However, any starches in the sugar may gum up the bees' digestive system, so this approach should not be used too often: kosher sugar may avoid this problem, as may grinding the powdered sugar in a coffee grinder to help make it more fine. Again, a slider board used in conjunction with the sugar dusting will let you count the mite drop. Again, see the HBHC guide, linked above.
Testing for Nosema:
(To learn more about Nosema, click here.)
Nosema ceranae, a microsporidan that infests the bees' gut, can lead to dysentery and weakening of bees, making it harder for them to process nutrients. This problem is particularly serious in winter, when bees can't forage. Nosema can only be detected by testing a sample of bees under a microscope. See below for directions re: how to take a sample and send it to the WSU APIS lab for testing. These tests are free (other than postage).
WSU TESTING LAB - directions for taking & sending a sample of your bees for testing: click WSU Sample Testing Form Directions
TRACHEAL MITE INFORMATION:
Tracheal Mites Life Cycle: thanks to LCBA member Renzy Davenport for these handouts.
Above, alcohol testing for Varroa mites: the small brown circles are the mites. Below, bees in a sugar shake jar:
To see a video of how to do a sugar shake, click here.
Above, the sugar-shaken bees return home.
Above, brushing powdered sugar into frames to knock down phoretic (hitchiker) Varroa mites. This is probably more sugar than ideal, particularly over that central brood chamber area. To see a video of how to do the sugar dusting, click here.
To sample mite drop using a sticky board, spray the board with olive oil & insert beneath screened bottom board. For discussion & examples, see Randy Oliver, scientificbeekeeping.com: Oliver offers excellent information & research on Varroa mite control.
Some facts about Varroa mites:
* Varroa mites live only 2-3 days without live bees to suck hemolymph from – bees robbing deadout hive can bring varroa back if any parasitized bees in hive being robbed are still alive.
* How many mites on a sticky board are a problem? 1 mite per hour is considered a warning threshold in fall ; in spring, with less brood present for mites to lay in, be more conservative in estimating problems.
Randy Oliver notes problems in relying on natural mite drop – see his site – he encourages using sugar dusting to aid knockdown & diagnosis.
Oliver also recommends that to clean sticky boards, scraping with ice scraper is quick & easy.