After three years of misfortunes from weather and disease, Alberta beekeepers may finally have some good news.
A new mite control product, Apivar, with its active ingredient, amitraz, has been given emergency registration and will be available this fall for all beekeepers to treat their bees before they winterize hives.
Apivar was available late last year and the few beekeepers who were able to use it had overwintering losses around the normal 15 per cent. In the last few years, losses have averaged close to 30 per cent and another 13 per cent of colonies have had fewer than three frames of live bees instead of the minimum eight needed for a productive hive. Canadian beekeepers are fortunate to have access to the chemical, which is produced by the French company, Arista, and is not registered in the U.S.
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Varroa mites are external parasites of honey bees that spread from Asia around the world starting in the 1960s. It reached the U. S. and Canada in the late 1980s. It feeds on the bees’ hemolymph – their “blood,” and leaves open wounds on their bodies. An otherwise-healthy bee can tolerate a few mites, but mites weaken bees and lead to deaths, especially over the winter when bees gather in a ball to prevent each other from freezing, and mites can spread between bees easily.
Beekeepers have been using two other products, but they are no longer effective. Treating bees with mite-killing chemicals in fall and sometimes in spring has allowed beekeepers to control varroa mites, but the mites have developed resistance to every chemical used against them.
Chemicals kill about 95 per cent of mites, so those that remain produce resistant populations. Apivar is the latest chemical, but it may not fend off varroa mites for long.
“It cleaned up almost all the varroa mites for the people who used it last year,” says Terry Greidanus, president of the Alberta Beekeepers Commission. “They found zero, one or two mites per bee this spring. That’s negligible compared to the 20, 40, 80 or even 100 mites per bee we had been finding. “Apivar has taken one big stress, our biggest problem, off the bees, but only until the mites get resistance. We have to monitor our bees very closely to track mite numbers on them. Then we have a chance to recognize a problem and decide what to do about it.”
LOOKING FOR OPTIONS
Paul Laflamme, Alberta Agriculture head of pest surveillance, is screening for other chemicals to control mites in the hope of having four or five registered miticides with different modes of action. That would allow beekeepers to rotate pesticides and prevent resistant strains of mites from developing. Using several products is generally a more sustainable practice than depending on pesticides with a single mode of action.
Another bee disease called nosema can also cause heavy overwinter losses of bees. Nosema is called a silent killer of honey bees because bees can continue to work until they succumb to it. It upsets digestion, causing diarrhea and eventually starvation. In the hive, infection can spread throughout the whole colony, especially when other stress such as high mite loads or very cold weather have weakened the bees.
Nosema can be controlled by medication in a sugar solution, but the bees may not consume the correct dose and it’s difficult to know whether the treatment has been effective. Also, bees have no immunity to new types of nosema that have infected them recently.
The Bee Health Program is helping beekeepers fight problems before they cause huge problems. Provincial bee specialist Medhat Nasr has been training beekeepers to monitor mites and nosema. Beekeepers can track the effectiveness of their management, identify stresses on their bees and take action to protect bees.
As well as the damage varroa mites do directly to bees, they can carry viral diseases, including some implicated in colony collapse disorder, which has decimated colonies in the U.S. It occurs during the summer, unlike Alberta losses, which occur in winter.
Beekeepers hope bee health will improve so they can depend on their pollination services. Healthy bee colonies are vital to high pollination rates in seed canola and other crops.
“We get more of our income from pollination services than from honey,” says Greidanus. “But we need strong bees. The number of bees we can provide affects our paycheque.”
