In Atlantic Canada, honey bees (and beekeepers!) endure long winters. Many of us wrap and winterize standard Langstroth hive bodies with different insulating materials to help colonies survive the cold winter months. However, what if it was possible to house our bees using a more insulating material all the time? Beekeepers currently have additional options and a choice of technologically advanced materials for housing colonies. One such novel material is polyurethane honey bee hives.
Overwintering in polyurethane hives
Polyurethane hives are an alternative to traditional, wooden
Langstroth bee hives. Similar to Langstroth hives, polyurethane hives use
standard size, removable frames in vertically stacking bodies. They are
advantageous because of their lightweight, insulating walls. High insulation
value offers potential to support honey bee colonies kept in cold climates.
During the winter, colonies are primarily focused on regulating cluster temperature
at around 34-35°C. This is an energy demanding task, at a time during
which foraging for food resources is not possible. Supporting colonies with
insulation can reduce energy needs, much like insulating a home reduces heating
costs. This can extend food stores, which is a great relief in the spring when
beekeepers are anxiously awaiting the first nectar bearing flowers.
Researchers in Maryland recently performed a study to
compare the overwintering capacity of polyurethane hives with standard,
soft-wood Langstroth hives (Alburaki and Corona 2022). Eighteen double deep,
10-frame hives, evenly divided between polyurethane and wooden, were standardized
for bees and food stores before the winter period from December to March.
Sensors were placed within each hive to monitor temperature and humidity, not
of the honey bee cluster, but of the surrounding hive cavity. Polyurethane hives maintained significantly
higher internal temperatures than wooden Langstroth hives, as well as less
drastic temperature oscillation between day and night. Polyurethane hives had an
average temperature of approximately 10.20°C,
compared to unwrapped, wooden hives at 9.73°C. During the monitoring period,
outdoor apiary temperatures ranged from -10 to 20°C, with an average of
0°C.
Another challenge for honey bees in the winter is maintaining
optimal hive humidity. Polyurethane hives maintained an average humidity more
preferable to honey bees at 52.05%, compared to 63.50% average humidity within
wooden hives. Polyurethane hives have vents in the top and bottom that provide
valuable airflow. Comparatively, the wooden hives revealed a wider range of
humidity between night and day, demonstrating wood’s propensity to absorb
moisture during cold, nighttime temperatures and then release moisture as the
day warms. Such oscillation of internal conditions may cause honey bees to use
more energy to maintain an optimal environment, thereby consuming more food.
It is important to recognize that the Langstroth hives in this
study were not winterized. In preparation of long, cold winters it is typical
for Atlantic beekeepers to insulate hives to some capacity, whether it is a
foam board between the inner and outer cover or bubble-wrap around the outside
hive body. Though this study does not provide insight as to the advantage of
polyurethane hives compared to wrapped, insulated Langstroth hives, it does
present a modern option for overwintering colonies. Polyurethane hives may be
an alternative technique for northern beekeeping, in which external wrapping
during the winter is not necessary.
At the Atlantic Bee Tour this summer in Nova Scotia, we saw an example of one beekeeper who is already taking advantage of the high insulating properties of polyurethane bee hives. Ben Cornect showed beekeepers his nuc yard, where he has begun successful experimentation with overwintering nucs in polyurethane hives! As innovation in beekeeping continues, it is worthwhile to consider your own operation and how new technologies might serve your beekeeping goals.
References
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