WASHINGTON State University researchers are suggesting a mid-season hibernation can help in the fight against Varroa mites.
This after assistant entomology professor Brandon Hopkins, manager of the university’s bee programme, put 200 honey bee colonies into refrigerated storage last August at a time when bees are still active but have finished making honey for the season.
It’s also when beekeepers normally do a round of mite treatments.
Hopkins says most treatments only kill Varroa on adult bees.
“A lot of mites live in the brood, which are under a wax cap that treatments can’t touch,” he says. “Those bees hatch out and are already afflicted.”
By placing colonies in refrigerators, the queen stops laying new eggs. When the bees come out of refrigeration, there is no capped brood.
At that point, Hopkins and his team applied a Varroa treatment on the adult bees.
The initial results were overwhelmingly positive. Researchers found an average of five mites per 100 bees on the control colonies (not refrigerated) one month after the normal three-cycle mite treatment.
The refrigerated colonies had an average of 0.2 mites per 100 bees one month after the single mite treatment.
“That’s a significant decrease,” Hopkins says. “Refrigeration is expensive, so we need to do more work to prove the cost is worth it for beekeepers, but we’re really excited so far.”
The infestation levels varied tremendously from colony to colony in the control samples. That’s because of the difficulty in treating colonies consistently over three cycles. The colonies that had the refrigeration treatment had consistent mite numbers with little variation.
After hearing about the research, beekeepers approached Hopkins about doing a similar round of refrigeration in the early spring.
“Beekeepers generally have two periods of time for mite treatments, before the bees make honey and after,” Hopkins says.