What's the Buzz with ATTTA #66

Thursday, 23 September 2021

On Wednesday, September 22, 2021, we officially welcomed the season of fall with the Autumn Equinox. Across Atlantic Canada beekeepers are busy working to make sure colonies are sent into overwintering in good strength and health to give the bees their best chance of surviving through to the following spring. Over the past couple weeks, we have been focused on the topic of fall feeding in preparation for winter. This week, we get back to the basics and discuss some important aspects of fall varroa mite management.

Apivar is now available at beekeeping supply stores! There was a delay in shipping, but the product is now back on the shelves and ready for use. It is not too late to treat! Strips that go in the end of September come out the beginning of November, leaving enough time to get hives wrapped before tucking them in for winter. As always, before using Apivar, first confirm that mite levels are above the economic threshold for using a synthetic chemical treatment (fall: 2 mites/100 bees).

If you have not already been following the excellent podcast series, The Wild View on Blueberries, check it out.  This podcast, created by blueberry specialist Hugh Lyu, is of interest to anyone involved in wild blueberry production and pollination!  Available anywhere you download your podcasts or through the link: https://www.perennia.ca/portfolio-items/wild-blueberries/ .


Happy Fall: Time to Get Out The Mite Sampling Jars!

Varroa mite control is one of the most important parts of honey bee colony management, especially during autumn when beekeepers are preparing hives for winter. In the fall, as brood rearing decreases, the population of varroa mites in a hive appears to increase. However, this apparent increase is because the colony is producing less brood which leaves less active brood cells available for mites to reside and reproduce in. This forces the mites in the colony to shift from brood cells onto adult bees, making them more likely to be subject to a round of mite treatment. Thanks to this shift, fall presents an opportune time for more direct and intentional varroa mite management.


SAMPLE

A proper varroa mite sample gives the beekeeper an accurate representation of the current infestation level of varroa mites in a particular hive. This sampling indicates whether treatment is warranted. Since mites move from brood cells to adult bees in the fall, the bees working on brood frames are most likely to act as hosts for mites and are therefore the best candidates for varroa mite samples. For more information on how to properly sample for varroa mites, see ATTTA’s “Summer Disease and Pest Monitoring in Honey Bees” factsheet.

TREAT

Since there is a larger proportion of mites on adult bees in the fall, the economic threshold for treating mites with a synthetic chemical is higher in the late summer/early fall compared to late spring/early summer (2 mites/100 bees in Aug vs. 1 mite/100 bees in May).  If the infestation is above the economic threshold, treatment is recommended. If the sample is positive but the infestation is below the economic threshold, perhaps an organic chemical or other approved non-synthetic chemical treatment may be used. Whatever your decisions are for management of varroa mites, ensure to follow the best practices as outlines for Integrated Pest Management (IPM). For more information on varroa action options, see ATTTA’s “Varroa Mite Management Options for Atlantic Canada” factsheet.

RE-SAMPLE

Perhaps the most important step of varroa mite management is re-testing varroa mite infestation levels after the treatment period. By re-sampling after treating, a beekeeper is able to:

  • Determine whether the treatment used was successful
  • Get an indication of resistance development in the mite population
  • Take immediate, informed, and intentional action as required
This is part of an IPM approach to varroa mite control and recommended as best management practice!

RESISTANCE*

Synthetic chemical varroa mite treatments (e.g., Apivar) must be used responsibly.

Mites have developed resistance to synthetic chemical miticides in the past and many beekeepers suffered significant losses because of it. As an example, one synthetic miticide used to treat varroa mites in Canada, a pyrethroid fluvalinate branded as Apistan®, was a very popular product that was widely used with little treatment variation in operations. By 2001, beekeepers from multiple Canadian provinces found Apistan-resistant mite infestations in their hives*. As an emergency solution, Canada issued permits to beekeepers for an organophosphate miticide, coumaphos (Checkmite+®, Bayer), to use for varroa mite management. However, varroa mites quickly developed resistance to this treatment product as well, first in Ontario by 2002 and later throughout other regions of Canada*.

Reviewing this significant event in the near past reminds present day beekeepers of the importance of maintaining good integrated pest management strategies with reliable cultural and physical controls, and not repeatedly relying on one treatment application, especially those to which pests are capable of developing resistance.


*Currie, Robert W., Stephen F. Pernal, and Ernesto Guzm├ín-Novoa. “Honey Bee Colony Losses in Canada.” Journal of Apicultural Research 49.1 (2010): 104-06.

 


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