The Atlantic Tech Transfer Team for Apiculture is continuing with a third year of a regional Varroa mite survey. This survey aims to determine seasonal trends in Varroa mite levels across the region, and help assess the efficacy of mite management options. This week’s blog will explore early season trends in Varroa mite populations across the Maritime region, and discuss how this year’s mite levels compare to 2024 and 2025.
Early Season Regional Trends in Varroa Mite Populations
For the
third season, ATTTA is conducting a regional Varroa mite survey to assess
temporal trends in mite levels and to assess the efficacy of amitraz (active
ingredient in Apivar®). This year, the survey consists of 17 beekeepers (8 in
Nova Scotia, 6 in New Brunswick, and 3 on Prince Edward Island). Many of these
beekeepers have participated in the last three years of data collection. For
trial one, which took place around the time of wild blueberry pollination (May
13, 2026 – June 16, 2026), there was a total of 55 samples/colonies included.
Overall, the
average mite load for trial one was 0.07%, 87% of colonies had 0% mite load,
and 2% of colonies had a mite load greater than 1% (Figure 1; Figure 2). The
average number of bees per sample for trial one was 313, with a target sample
size of 300. In comparison, in 2025, the average mite load for trial one was
0.02% and in 2024 the average mite load was 0.09% (Figure 2)1. A
reminder to beekeepers that it is recommended to maintain mite levels below 1%
throughout the beekeeping season.
Figure 1. Comparison of average Varroa mite loads in the Maritime region between 2024, 2025 and 2026 during the early beekeeping season.
When
comparing early season levels of mites in 2026 to previous years, a higher
percentage of samples had detectable mite levels (at least one mite per
sample), however, the number of samples with mite levels above 1% was
in-between what was found in 2024 and 2025 (Figure 2)1. This final
season of data collection will help provide a solid baseline of the trends in
mite levels across the beekeeping season.
As the ATTTA
team continues to collect Varroa mites throughout the survey, the goal will be
to conduct lab-based testing to assess the efficacy of amitraz within the
Maritime region. Beekeepers must remain vigilant regarding the efficacy of
Apivar® as this is the only recommended synthetic miticide available, and
reduced efficacy is being reported across the globe.
Recently
published research found that colonies managed in Auburn, Alabama, US that were
treated with Apivar® late season had maintained Varroa mite levels over a
63-day period, whereas colonies not treated with any products showed
significantly increased mite levels2. The study demonstrated that
within the research colonies, Varroa mites still have a level of susceptibility
to amitraz which can effectively prevent mite levels from quickly increasing during
the late season. However, the research also found that the amitraz resistance
genotype (Y215H mutation) significantly increased from Day 0 to Day 63 after
the application of Apivar, which further demonstrates that Apivar
application selects for individuals with the amitraz resistant genotype thereby
increasing resistance levels in a population of mites.
Overall,
early season trends in Varroa mite populations across the Maritime region are
low and well managed based on the amount of samples processed. However, beekeepers
must remain vigilant when monitoring for mites, and practice integrated pest
management in all aspects of their mite management. 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 one of our survey. We will be
reporting on trial two of our survey in the near future, as trial two will be
concluding shortly.
References
- 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
- Tokach, R., Rinkevich, F., Aurell, D., Egnew, N., Cargo, K. and Williams, G.R., 2026. Evaluation of late-season Varroa destructor treatments and their impact on amitraz resistant mite populations. Scientific Reports.
Connecting with ATTTA Specialists
If you’d like to connect with ATTTA specialists or learn more about our program, you can:
visit our website at https://www.perennia.ca/portfolio-items/honey-bees/
Email attta@perennia.ca