When inspecting a honey bee colony the presence/absence of brood (eggs, larvae and pupae), and the overall appearance of brood, can tell a beekeeper a lot about their colony’s well-being. It can indicate to a beekeeper how well a colony is developing, the presence and performance of the queen, the availability of resources to the colony, and the presence of various pests and diseases. Read this week’s blog to learn more about how the brood can provide an indication of colony health, and what beekeepers should be looking for when inspecting their brood.
Brood Indicators of Colony Health and Resource Availability
The first
thing to recognize when discussing honey bee brood is that the abundance of
brood will naturally change with the beekeeping season. Bees can start rearing
brood as early as February within Northern climates, and brood rearing will
increase throughout March and April. In the Maritimes, some brood is likely to
be present in the colony by the time beekeepers can first start to inspect
their colonies for the current season. Brood rearing will continue at a steady
rate during the months of May to July, and, in a typical season, there will be
a dearth period mid-summer which will reduce brood production. Following the
usual dearth period (mid-August) the colony will start to rear their winter
bees, and will continue to rear brood until October. Keep in mind that the
beekeeping season will vary year-to-year depending on the weather, which will
have an impact on the timing of brood availability, and should be considered
when judging the health of colonies based on brood indicators.
New research
demonstrates that a low abundance of brood (based on a brood to bee ratio) can
be a strong indicator of if there is low forage availability for the colony1.
The study shows that, during peak brood production, a brood to bee ratio of
less than 1 can indicate environmental stress (such as limited forage
availability). Bees require pollen for brood rearing. Pollen provides protein,
fats, vitamins, minerals and amino acids that brood development requires2.
When pollen availability is low in the environment brood production slows down.
Not only should a beekeeper look at the abundance of brood, but also the
appearance of the brood. Wet brood indicates the larvae are being fed well, and
dry brood reflects inadequate nutrition for feeding the larvae (i.e.
pollen/protein deficiency).
The presence
of drone brood can also tell a beekeeper something about the colony’s
well-being. Drones are reared when there is an abundance of resources within
the hive. Seeing some drone brood within the colony is a good sign the colony
is well nourished. In stressful conditions drone production is the first thing
to stop. Keep in mind that a lot of drone brood can indicate the colony has a
drone laying queen or a laying worker.
Brood
indicates if a colony is queen right, and if the performance of that queen is
good. First, if eggs and young larvae are present within the colony a beekeeper
can have confidence that the colony is queen right. Sometimes it is a challenge
to find the queen within a colony, and simply looking for eggs can let a
beekeeper know she is present. One indication the queen is performing well is
the overall brood pattern. Ideally, the brood should be located at the center
of the hive, and, on a single frame, food resources should form an arch over
the brood3. Additionally, beekeepers should check if the brood pattern
is solid (not “spotty” with many empty cells). A spotty brood pattern may
indicate a poor performing queen, and may also be a sign of various brood
diseases.
Beekeepers inspect brood to look for signs of diseases.
There are several brood disease beekeepers should be aware of and inspect for
throughout the season. The first one to mention is European foulbrood (EFB).
EFB appears in weak colonies or during times of stress. Typical signs of EFB
include: larvae are twisted/coiled within the cell, larvae are discoloured
(yellow to brown), and the presence of dry dark brown scales on cell walls
(scales are easy to remove). The second brood disease to discuss is American
foulbrood (AFB), which is a reportable disease. AFB is highly contagious, it is
not a stress related disease, and can infect the strongest to the weakest
colony in an apiary. The main signs of AFB to look for include: scales that
adhere tightly to the base of the cell, perforated holes within the brood
cappings, brood that has a sunken and greasy appearance, and brown coloured larva
and pupa. In most cases, AFB can be reliably distinguished from other honey bee
brood diseases using the “ropiness” test. Finally, Chalkbrood is another brood
disease found within Atlantic Canada. Chalkbrood is a common stress-related
disease, but usually does not cause significant colony losses. Chalkbrood is
easy to identify in a hive. Beekeepers should look for black, grey or white
mummies on the bottom board, in cells, or just outside the hive entrance.
Overall, inspecting brood provides a lot of information to a
beekeeper. Beekeepers should regularly inspect the abundance, stage, caste, and
appearance of brood to help determine the overall health of a colony. To learn
more about colony health and brood production read future blogs from ATTTA.
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
- Groeneveld, J., Odemer, R. and Requier, F., 2024. Brood indicators are an early warning signal of honey bee colony loss—a simulation-based study. Plos one, 19(5), p.e0302907.
- Groot, A.D., 1952. Amino acid requirements for growth of the honeybee (Apis mellifica L.). Cellular and Molecular Life Sciences, 8(5), pp.192-194.
- Camazine, S., 1991. Self-organizing pattern formation on the combs of honey bee colonies. Behavioral ecology and sociobiology, 28, pp.61-76.
