As the beekeeping season progresses, the Atlantic Tech Transfer Team for Apiculture has been continuing to survey regional Varroa mite levels. Our team has now completed the second trial of the season which assessed mite levels mid-season. Continue reading this week’s blog to learn more about mid-season trends in Varroa mite populations across the Maritime region, and for insight on a comparison of this year’s mite levels with 2024 and 2025.
Mid-Season Regional Trends in Varroa Mite Populations
The second trial of ATTTA’s Varroa mite
survey consisted of 16 beekeepers (7 in Nova Scotia, 6 in New Brunswick and 3
on Prince Edward Island). The second trial took place between July 1 and August
11, 2026 following wild blueberry pollination, and consisted of samples from 57
colonies. These colonies were all from commercial beekeepers who provided
pollination services.
Overall, the average mite load for trial
one was 0.09%, 84% of colonies had 0% mite load, and 3.5% of colonies had a
mite load greater than 1% (Figure 1; Figure 2). The average number of bees per
sample for trial two was 316, with a target sample size of 300. In comparison,
in 2025, the average mite load for trial two was 0.3% and in 2024 the average
mite load was 0.16% (Figure 1)1.
Figure 1. Comparison of average Varroa mite loads in the Maritime region between 2024 to 2026 during the middle of the beekeeping season.
Between trial one and trial two Varroa mite
levels slightly increased, which demonstrates the usual trend of levels
increasing as the season progresses. However, the increase in levels between
trial one and two for the 2026 season is less than that of the 2025 or 2024
season. This is an interesting observation that needs to be investigated
further as there are multiple reason why a smaller increase in mite levels has
been observed. This could be due to random sampling, and there is not a true
difference between seasons, or beekeeper management practices are having a
positive impact on keeping mite levels low throughout the season (i.e.
effective spring treatments, monitoring, and/or providing mid-season
treatments). Following the end of the survey, the team will survey all
participants on their management practices to better understand these trends.
Additionally, following trial three, it will be known what the mite levels
were, on average, at the end of the 2026 beekeeping season.
Figure 2. Comparison of Varroa mite loads in the Maritime region between 2024 to 2026 during the middle of the beekeeping season.
After three seasons of data collection, and
one more trial to be completed in September, the team has gained a solid understanding
of the range of mite levels within the Maritime region at discrete time points
in the beekeeping season. Understanding what the range of mite levels are
early, mid and late season allows beekeepers and researchers to understand when
mite levels deviate from what is typical, which can occur for a variety of
reasons such as management practices, efficacy of products and changing
climate.
Beekeepers must remain vigilant when
monitoring for mites, and practice integrated pest management. A reminder to
beekeepers that it is recommended to maintain mite levels below 1% throughout
the beekeeping season. For questions regarding mite management and treatment
please reach out to the ATTTA team. We would like to thank all beekeepers who
participated in trial two of our survey. We will be reporting on trial three of
the survey, and the final results of the three-year project, later this fall.
References
1.
Atlantic Tech Transfer Team for
Apiculture. 2025. Maritime regional survey on the prevalence of Varroa mites (Varroa
destructor) in western honey bee (Apis mellifera) colonies, and the
efficacy of amitraz for treatment. https://www.perennia.ca/wp-content/uploads/2018/03/Varroa-mites-REPORT-2025.pdf