ATTTA Varroa Mite Survey Late-Season Summary

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.

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 abyers@perennia.ca

The Atlantic Tech Transfer Team for Apiculture has been busy this past summer conducting research in apiaries, wild blueberry fields and within our own lab facilities. Our projects have largely focused on supporting the pollination industry and on honey bee health. Read this week’s blog for a brief summary of our main projects from summer 2024.

Summary of ATTTA Summer Field Work 2024

ATTTA Regional Varroa Mite Survey

This summer ATTTA has been conducting a regional Varroa mite survey involving 23 different beekeepers from New Brunswick, Nova Scotia and Prince Edward Island. These beekeepers represent a significant portion of Maritime beekeeping operations. The survey is intended to broadly sample across the Maritime region. Those who participate have been asked to provide ATTTA with 3 samples of approximately 300 honey bees 3 times throughout this beekeeping season (prior to pollination, after pollination and late season). Samples were only taken from commercial beekeepers who use their colonies for wild blueberry pollination. 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 possible future testing (e.g. tracheal mite). In next week’s blog we will provide details of the results of the survey to date.

ATTTA apiculturist (Kayla Gaudet) conducting an alcohol wash to assess Varroa mite load in a colony (Perennia©2024).

Pollination Efficiencies for Wild Blueberry Production

ATTTA has a continued goal of supporting the wild blueberry pollination industry. This year ATTTA had three projects that focused on assessing wild blueberry bloom, and the requirements (timing and stocking density) of pollination units. The first project involved assessing wild blueberry bloom during the months of May and June. The aim of this project is the creation of a growing degree day bloom model, using local weather stations, to better predict the timing for placement of pollination units. An original GDD model of wild blueberry bloom was based on a single field and across one season (White et al., 2012).  At the time of publication, the authors recommended the need for additional data sets to be collected, throughout the region. This improved model will also include the endodormancy and ecodormancy requirements of the wild blueberry plant to establish a starting point for GDD modeling.  This is now the second year of this three-year collaborative project with Dalhousie University and ATTTA.  The second project involved assessments of sprout year fields. The goal of the project is to assess how early in the year floral and leaf buds can be distinguished, and how early accurate bud counts can be achieved. This will help to determine the crop year floral density as a predictor of pollination requirements. The hope is to support blueberry producers and beekeepers through a better understanding of bloom as one component of a predictive model determining the demand for pollination services. Finally, ATTTA followed up on a study from 2022, that assessed sequential loading of honey bee units on wild blueberry fields. This study will validate the previous work by repeating the 2022 trial on limited number of fields with are reversal of the control and treatment groups.  ATTTA will be reporting on all wild blueberry pollination work in the months to come.

ATTTA seasonal apiculturist (John MacDonald) presenting at the Bleuets NB Blueberry meeting in East Galloway, NB in July (Perennia©2024).

Queen Rearing

The ATTTA team has slowly started to resume rearing queens for research purposes. This summer we focused on building up colony numbers, as any queen producer knows it takes an abundance of bees and resources to raise queens. A member of our team received specialized training to learn how to raise queens on a large commercial scale, and ATTTA has plans to resume research on outdoor overwintering of banked queens starting next season.

Queen honey bee (with green marker) surrounded by her attendants (Perennia©2024).

Bumble Bee Captive Breeding and Overwintering

The final project to discuss is ATTTA’s work involving captive breeding, housing and overwintering Bombus impatiens. As a continuation from last year’s trials, the ATTTA team captively bred Bombus impatiens queens on a weekly basis throughout July and August. After mating, queens were cared for daily in ATTTA’s indoor facility. Each queen was kept in a temperature-controlled environment and fed both pollen and sugar water. The team also exposed each queen to the needed conditions to stimulate her to start producing brood. These conditions included a small amount of carbon dioxide exposure and a low temperature environment for a period of time. The intention of the project is to now manage these queens into the winter months. There were multiple objectives to meet throughout this project, including: evaluating the percentage of queens that artificially mate: assess if mated queens will produce honey cups, eggs and larvae; assess the timeline of colony build-up; determine the time a mated queen will survive in simulated diapause; and determine if queens will survive diapause long term (i.e. through the winter). Overall, this project allows the team to gain a deeper insight into these important pollinators and to better support producers relying on insect pollination.

ATTTA seasonal apiculturist (Greg Dugas) feeding bumble bee queens (Perennia©2024).  Work is undertaken in red light as this is invisible to bees.

References

White, S.N., Boyd, N.S. and Van Acker, R.C. 2012. Growing degree-day models for predicting lowbush blueberry (Vaccinium angustifolium Ait.) ramet emergence, tip dieback, and flowering in Nova Scotia, Canada. HortScience, 47(8), pp.1014-1021.

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 abyers@perennia.ca