To effectively manage Varroa mites, beekeepers must adapt an integrated pest management approach, which includes various chemical, physical and cultural methods. Although the use of chemicals is important, beekeepers should not underestimate the value of the many cultural and physical methods available to keep mite levels under control prior to intervening with chemical treatments. This week’s blog will focus on specific non-chemical practices beekeepers do that help manage Varroa mites within an operation.
The Advantage of Splitting for Varroa Mite Management: an IPM Approach
It is a
common practice of beekeepers to split colonies of bees each spring and summer.
How often, and when, beekeepers split colonies depends on the needs of their
operation. Typically hives are split in May, prior to pollination, which helps
beekeepers equalize colonies prior to sending them to pollination, and can
provide nucleus colonies to sell or keep. Hives can also be split following
pollination, in June and July, which helps beekeepers prevent colonies from
swarming, and can also increase their number of colonies. What beekeepers may
not think of when splitting is how this practice helps manage Varroa mites.
To
understand why splitting helps manage Varroa mites, it helps to have a general
understanding of the Varroa mite life cycle. Mites spend part of their life
cycle attached to adult bees, but move into brood cells to reproduce. A female
mite will enter a brood cell just before it is capped, and she will lay her
eggs within the cell. Then, once the bee emerges from the cell, any mature
female mites will leave the cell to continue the life cycle. What this means is
that the presence of brood is essential for mites to reproduce and grow their
population. If there is a break in brood production, such as when a beekeeper
splits a colony, this also creates a break in mite reproduction.
Splitting a colony creates a break in the honey bee brood cycle, but this break will differ in length depending on how the beekeeper chooses to make the split. The longest break resulting from a split is what beekeepers call a “walk away” or “queenless” split, which is when the beekeepers leaves the bees to make their own queens. From the day the colony is split, it will take approximately 14 days for a new queen to be made and emerged into a colony. It will take 5-7 days before the queen takes her orientation flight and mating flight. It will then take another 5-7 days before she starts to lay eggs, and workers will not emerge from the cell until 21 days after that. This means no new brood will emerge for at least 43 days after the split was done. It is important to understand that mite reproduction can resume once the queen starts laying eggs. So the 43 days to new brood emergence in walk away splits may only include a 22-day break in mite reproduction, which can significantly reduce population growth.
Another
option beekeepers may choose when making splits is introducing queen cells.
This option provides a shorter break in the brood cycle than a “walk away” or
“queenless” split, but still provides a benefit of slowing mite reproduction.
When a queen cell is introduced to a newly made split, the queen will emerge
within the next 3-4 days depending on what day the cell was harvested and how
long it was incubated. This means no new brood will emerge for approximately 33
days after the split was done, and provides an approximate 12-day break in mite reproduction.
Finally,
beekeepers may choose to introduce a mated queen into their newly made split.
This provides a much shorter break in the brood cycle as the queen will start
to lay eggs shortly after being introduced into the colony, which allows mites
to quickly resume reproducing.
Splitting
colonies is something beekeepers do regularly, and it is an added advantage
that it slows mite population growth. Beekeepers should consider the fact that making
splits can be part of their integrated pest management approach to managing
Varroa. Beekeepers should remember to monitor for Varroa mites each month
during the beekeeping season to assess if their integrated pest management plan
is working. Finally, there are other cultural and physical methods of managing
Varroa mites, which will be explored in future blogs.
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