| Drone
brood removal research
Mites are found most often on drone
brood where they produce about twice as many offspring as
on worker brood. Therefore, by removing capped drone brood
from an infected colony, you remove a disproportionately large
number of mites without affecting the worker population, and
you remove those mites with the highest fecundity. Research
at Dyce Laboratory for Honey Bee Studies at Cornell University
has shown that the periodic removal of drone brood from a
colony allows a beekeeper to skip the usual spring treatment,
keep mite levels low throughout the summer and prevent fall
collapse (figure 1). It may also eliminate
the need for a fall pesticide treatment. The only way to determine
that is to estimate the pest density on a colony-by-colony
basis after removing the fall honey crop.
Implementation: You will need four drone
combs per colony to use this method. Drone foundation can
be purchased from several supply houses. The foundation is
wired into frames and drawn out by colonies. One piece plastic
drone combs are also available. Use two deep hive bodies for
brood chambers, and separate them from the honey supers with
a queen excluder. Cull worker combs in the brood nest with
more than 1 to 2 square inches of drone cells (photo H). Remember!
The goal is to get the colony to consolidate all of its drone
production in the removable drone combs.
Place two drone combs in the upper brood chamber, one or
two combs in from each side. Visit your colony every 26 to
28 days, remove the drone combs (photo I) and replace them
with the drone combs that you removed on the previous replacement
date. Place the combs of capped drone brood in a freezer,
and keep them there until you are ready for your next exchange.
Allow frozen drone combs to come to ambient temperature before
placing them back in a colony. Be sure to visit your bees
at least every 28 days to exchange combs because you don't
want too many drones actually emerging in your hive. If a
drone comb becomes filled with honey, you will need to substitute
an empty drone comb and extract the honey before reusing it.
In the north, you can exchange combs up to six times a season
using a 28-day interval between exchanges. The more often
you exchange combs, the more you will suppress the mite population.
The drone brood removal method has no known deleterious effects
on colonies, and honey production may be marginally increased.
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Photo H. Comb
of capped drone brood being removed from colony. |
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Photo I. A worker
comb with excess drone cells. Such a comb is best
culled and replaced with a comb of 95-100% worker
cells. |
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