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Alberta honey bee winterkill drops in 2013-14

July 23, 2014 - Alberta Agriculture and Rural Development (ARD) recently released the results of its survey of winterkill of honey bees in 2014. Seventy-six per cent of commercial beekeepers who own 400 or more colonies responded took part in the survey. This group of beekeepers operates over 90 per cent of honey bee colonies in Alberta.

"The surveyed beekeepers reported wintering 197,038 honey bee colonies and nuclei,' says Medhat Nasr, provincial apiculturist, ARD, Edmonton. "Overall, beekeepers reported that 18.5 per cent of Alberta bees died during the 2013-2014 winter."

The reported winterkill varied from region to region. The lowest winterkill (15.1 per cent) was reported in southern Alberta south of Calgary (Region 1). The winterkill was 16.7 per cent in Region 2, which is north of Calgary to south of Edmonton. In the northeast central/St. Paul area (Region 3), the winterkill was 20.6 per cent. In the northwest (Region 4) beekeepers reported 16.5 per cent winterkill. In the Peace (Region 5) beekeepers reported 23.2 per cent winterkill.

"It is notable that the winterkill significantly decreased to 18.6 per cent in regions 2 and 3 this year in comparison to 2012-2013 where the reported winterkill was 37.5 per cent," says Nasr. "Beekeepers who wintered full size bee colonies in British Colombia reported the lowest winterkill in recent years at 10.5 per cent."

The survey included a list of suspected causes that could lead to killing bee colonies in winter. "This year, losses may be attributed to one or a combination of several factors that acted synergistically to kill bee colonies," says Nasr. "Beekeepers reported the most likely cause of winterkill to be cold spring and poor quality queens. In early March, 2014, beekeepers were reporting normal mortality (10-15 per cent) and the bees were looking good for that time of the year. However, because of a large snow pack and extreme unsettled conditions in the spring, the bee population dwindled and more bee colonies died. Surviving colonies were slightly weaker than normal colony strength."

Despite beekeepers having requeened their colonies in 2013 season, beekeepers complained about poor performance of imported queens and a high rate of supercedure. Nosema was the second cause of high winterkill cited by beekeepers. A Nosema outbreak was most likely associated with the late spring, resulting in confinement of bees inside bee hives for a longer period of time during the winter extending to spring. Starvation and small clusters of bees were mentioned as possible causes of winterkill but ranked very low.

Surprisingly enough, says Nasr, the Varroa infestation was ranked on the bottom of the list of possible causes of bee colony mortality. "It was reported that Varroa was under control in most operations in 2013-2014. Apivar continues to work effectively. The application of Apivar in early spring for Varroa control has proven at this point to be the most effective treatment time to keep healthy colonies through the season and for wintering. Fall treatment was late in some operations and consequently these operations reported high winterkill."

Over the winter of 2013–2014, 25 per cent of managed honey bee colonies died in Canada. The highest winterkill was 58 per cent reported in Ontario but the rest of the provinces averaged 19.3 per cent. The lowest winterkill was reported in British Colombia at 15 per cent.

"It was encouraging to hear that Quebec reported 18 per cent winterkill in 2014," says Nasr. "This is the lowest reported winterkill in Quebec in comparison to previous years. It is particularly remarkable that Alberta has decreased its bee winterkill rates by 50 per cent, going from 30 to 40 per cent from 2007-2010 down to 15 to 24 per cent in the last four years. Overall the average winterkill in Alberta is 20 per cent in the past four years. The significant decrease in winterkill rates has been attributed to the use of Varroa mite control products and the adoption of effective bee surveillance and management systems."


July 23, 2014  By Alberta Agriculture and Rural Development


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