In Early August, ATTTA published a blog that reported on the mid-season results of ATTTA’s Varroa Mite Survey. As our final trial of the survey wraps up, we wanted to provide our readers with an update on the survey. This survey is important to the Maritime beekeeping industry as it assesses the efficacy of mite management across our region. Read this week’s blog for a late-season summary of the results to date.
ATTTA Varroa Mite Survey Late-Season Summary
This
year ATTTA has been conducting a regional Varroa mite survey, which now
includes 23 different commercial beekeepers from New Brunswick, Nova Scotia and
Prince Edward Island. These beekeepers, representing a significant portion of
Maritime honey bee colonies, have been asked to provide ATTTA with 3 samples of
approximately 300 honey bees, 3 times throughout this beekeeping season (prior
to pollination, mid season and late season). The breadth of this survey was
intended to provide insight into the situation across the industry. This was not to replace monitoring by
individual beekeepers. The survey has
several main goals, including: determine Varroa mite levels across the region
at three important time points during the current season, collect Varroa mites
for miticide efficacy testing, establish temporal measurements for annual
comparison of Varroa burden for the Maritime region, and create a stored bank
of samples for future testing (e.g. tracheal mite).
This
blog provides a summary of all 3 trials to date, which occurred between May 11,
2024 to September 23, 2024.
To
date, ATTTA has received samples from 25 apiaries, 81 colonies, and processed a
total of 161 samples. For details on Varroa mite load, which is determined
using an alcohol wash, please refer to Table 1.
Table
1. Summary of results for ATTTA Varroa Mite Survey between May 11, 2024 and
September 23, 2024.
|
Sampling
Period |
Samples
Positive for Varroa Mites |
Samples Above
the Economic Threshold Requiring Treatment |
|
Trial 1
(Pre-Pollination) |
3 /42 (7%) |
1 / 42 (2%) |
|
Trial 2 (Mid
Season) |
20 / 75 (27%) |
4 / 75 (5%) |
|
Trial 3 (Late
Season) |
28 / 44 (64%) |
5 / 44 (11%) |
|
Combined Sampling
at three time points |
51 / 161 (32%) |
10 / 161 (6.2%) |
The
number of colonies with detectable Varroa mites from an alcohol wash increased
by 57% from early-season (pre-pollination) to late-season (Table 1). The number of colonies above the economic threshold increased by 9%
from early-season (pre-pollination) to late-season (Table 1).
ATTTA seasonal apiculturist (Greg Dugas) conducting an alcohol wash to assess Varroa mite load in a colony (Perennia©2024).
The
number of detectable mites increases throughout the beekeeping season, as shown
by the survey results. The results support what would be expected for changes
in mite populations from early season to late season. Since mite populations can grow rapidly, it
is crucial to monitor and treat as needed in early spring to ensure that
populations are low at the commencement of the season. By autumn, mite numbers should
be at manageable levels to ensure hives remain healthy through the winter. If
mite levels are too high by fall, colonies are at risk of not surviving the
winter months. Late in the season, beekeepers must monitor mite levels to
determine if treatment is necessary. Several treatment options for Varroa mites
are available in the fall, including Apivar®, Formic acid, Oxalic acid,
Thymovar®, and Hopguard®.
Conventionally
when monitoring, treatment is only indicated when the mite population reaches
or exceeds the economic threshold. Beekeepers should remember that current established
economic thresholds need to be contemplated against the changing climate and
lengthening of seasons. Also, treatments
should be applied in consideration of the mite populations across an apiary and
not on individual colonies. In recent years, the changing
beekeeping season in the Maritimes has increased the challenge of managing
Varroa mites. If you have questions about treatment options or when treatment
is needed, please reach out to the ATTTA team.
The
ATTTA team has nearly completed the final trial of the survey. We would like to
thank all beekeepers who have participated in the study. This broad survey
provides valuable insight into the situation across the industry. The ATTTA apiculturists have also finished
conducting testing on the efficacy of amitraz (active ingredient in Apivar). In
the coming months we will give results of the amitraz efficacy testing and
provide a comprehensive report on the 2024 survey.
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