Mass Overwintering of Queen Honey Bees

Thursday 22 September 2022

Fall has officially begun! For beekeepers, this is a time for feeding, hive treatments, and overwintering preparations. This fall, ATTTA is busy with overwintering preparations for a project about mass storage of queen honey bees. The logistics of overwintering mass numbers of queens in a bank is continuously being explored in Canadian honey bee research because of the implications it could have on the availability of early spring queens. In this week’s blog, we will discuss mass overwintering of queens by focusing on a recent paper released by researchers in Quebec.

Mass Overwintering of Queen Honey Bees

Queen availability in early spring is a significant obstacle for the Canadian beekeeping industry. In Atlantic Canada, cool weather makes it unrealistic to raise queens before June and yet overwintering losses need to be addressed in May before wild blueberry pollination. As such, it is common practice to buy imported queens from warmer climates. Mass overwintering of honey bee queens has the potential to curb this reliance on imported queens, strengthening our local industry and reducing the spread of harmful pests and disease. 

In 2018-2019, Quebec researchers successfully overwintered queen banks holding 40 queens per bank for eight months (Rousseau and Giovenazzo 2021)! Queen banks are colonies with multiple queens stored within. The queens are kept in cages on a modified frame to protect the queens from one another and allow access to the workers. Colonies banking queens need to be fortified with an abundance of food stores and worker bees for the greatest success (Wyborn et al. 1993). To prepare their queen banks, researchers used 30 colonies to make 15 strong, double brood chamber colonies holding 9-10 frames of brood and approximately 8kg of bees each (Roussea and Giovenazzo 2021). The queens were banked in September, then kept outdoors until November when they were moved indoors at varying ambient temperatures until April. The main objective of this research was to see if the banks would have greater overwintering success when stored at a temperature greater than clustering temperature. To test this, banks were kept at 6°C, 11°C, and 16°C. There were also 20 control colonies stored at 6°C, in which a single queen roamed freely. 

Figure 1. Queens banked on a modified frame. The back side of the frame holds and additional 20 queens, for a total of 40, and to the left of the cages is a data logger (Rousseau and Giovenazzo 2021).

In May of 2019, the queen banks were opened and queens were assessed. Banked colonies overwintered at 16°C had the largest number of queens survive the winter, with an average of 29 queens surviving. The control queens and banked queens were assessed for body weight, abdomen weight and length, and sperm viability. Banked queens in all temperatures had significantly lower body weight and abdomen length, but there was no difference in abdomen width or sperm viability between banked and unbanked queens. Researchers concluded that the results of the study are optimistic for Canadian beekeepers. There is potential to successfully overwinter a large quantity of viable queens to be ready for use in the early spring. The greatest success in this experiment was with banks overwintered at 16°C. This is not the industry standard for indoor overwintering, but it does present an interesting option for queen producers to explore. 

Table 1. Shows the average number of surviving queens in control hives and banks at varying temperatures (Rousseau and Giovenazzo 2021).

Although the research discussed above shows potential for overwintering queens indoors, this may not be as practical a solution for beekeepers in Atlantic Canada.  For this reason, ATTTA undertook a pilot study for mass outdoor overwintering of queens in the winter or 2021 - 22. This small-scale pilot study demonstrated that banked queens could survive outdoors in our region.  Due to the success of this project and with additional financial support of the Nova Scotia Beekeepers Association, this season we are developing the study to include more banks and queens. If this second overwintering project confirms our initial results, we will develop a more complete research project to establish practical outdoor overwintering protocols for beekeeper’s use in the Atlantic region.

Rousseau, A.; Giovenazzo, P. Successful Indoor Mass Storage of Honeybee Queens (Apis mellifera) during Winter. Agriculture 2021, 11, 402.
Wyborn, M.H.; Winston, M.L.; Laflamme, P.H. Mass storage of honeybee (Hymenoptera: Apidae) queens during the winter. Can. Entomol. 1993, 125, 113–128.

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