Source: USDA, 6/22/20 Putting honey bees into early indoor cold storage in October rather than November increases their chances of surviving the winter and the colonies emerge readier to pollinate almonds, according to a new Agricultural Research Service (ARS) website. Overwintering managed honey bee colonies in indoor cold storage in states such as Idaho has become increasingly popular with beekeepers because, in the cold, bees don't need to forage for food, be fed by beekeepers, or be treated for parasitic Varroa mites—a serious pest of honey bees. This cuts down on beekeepers' costs and can greatly reduce overwintering colony losses. Some beekeepers still move their
colonies to warm locations where their bees can forage and rear brood during
the winter, but this can be expensive. Since flowering plants that provide
nectar and pollen can be in short supply, colonies can finish winter smaller
and weaker, or be lost entirely. When indoor cold storage came on
the scene around 2017, colonies were put into the buildings in November because
the facilities did not have chilling capabilities and relied on cold outside
air to reduce temperatures in the building. Newer cold storage facilities have
controlled chilling, so colonies can be put into the buildings at any time. "Indoor cold storage is
still rather new and we are refining techniques every winter to optimize colony
survival and colony size just in time for almond bloom," said entomologist Gloria DeGrandi-Hoffman. She is the research
leader of the ARS Carl Hayden Bee Research Center in
Tucson, Arizona. One of the center's assignments
is to develop best management practices to reduce colony losses, especially
winter losses, and help make beekeeping more economically sustainable. Last fall, DeGrandi-Hoffman
reconsidered the cold storage start date of November because beekeepers often
have to do one last treatment of colonies in October for Varroa mites. By
bringing colonies into cold storage in early October, beekeepers could skip
that expensive treatment. "The rental fee for a colony
in a cold storage facility for the entire winter is about the same as one
miticide application," DeGrandi-Hoffman said. When put into cold storage
in October, 82 percent of the colonies survived the winter and were large
enough to rent for almond pollination compared to 76 percent of those put into
cold storage in November. Even better, she found with
October indoor cold storage, queens started raising brood again in mid- to
late-January. So these colonies emerged larger and stronger, just in time to be
transported to California to pollinate almond crops. Colonies put into cold
storage in October filled an average of 9.3 frames per colony in early February
compared to about 8 frames for those colonies cold stored in November. The number of frames per colony
is important because pollination contracts pay about $200 for colonies with
fewer than 8 frames of honey bees, while those with 9 frames or more fetch a
premium price about 6 percent higher. Nearly 2 million bee colonies are needed
each February to pollinate almonds. "October stored colonies
also have a lot more younger bees, which contributes to more premium colonies.
Bees from the previous fall's brood are already starting to die due to old age
in February," DeGrandi-Hoffman said. The research center recently
developed a Cold Storage Overwintering webpage that details
how to do indoor cold storage most effectively. This includes a tool to help
beekeepers decide which colonies to put into cold storage. The tool predicts
the chances of a colony surviving the winter and being large enough to rent for
almond pollination in February based on its size and Varroa numbers in
September. The tool helps beekeepers avoid investing feed, miticide treatments,
labor, transportation and cold storage fees on colonies that probably will be
too small to rent in February. For more information, please
check out ARS Honey Bee Health.
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