The Lives of Bees
Page 35
brood nest to keep its temperature within the narrow, optimal range of
34.5°–35.5°C (94°–96°F). The rate of heat transfer from (or to) a wild
colony living in a typical, thick- walled tree cavity is four to seven times
lower than for a managed colony living in a standard, thin- walled wooden
hive.
Difference 6: Colonies have small and high vs. large and low nest entrances.
This difference renders managed colonies more vulnerable to robbing
and predation, because larger entrances are harder to guard. It may also
lower their likelihood of winter survival, because low entrances are often
blocked by snow, which prevents bees from making cleansing flights, and
because low entrances make it more likely for bees to crash or land on the
snow while trying to make cleansing flights. Bees that settle on the snow
are often trapped there, unable to warm their flight muscles sufficiently to
fly back to their nest.
Difference 7: Colonies live with vs. without plentiful drone comb.
Depriving a colony of drone comb will inhibit it from rearing drones,
and this will boost its honey production and slow the reproduction of the
Varroa mites in the colony. But it will also hamper natural selection for
colony health, because it will prevent the healthiest colonies from being
the best at passing on their genes via drones.
Difference 8: Colonies live with vs. without a stable nest organization.
Disruptions of nest organization for the purposes of beekeeping may
hinder colony functioning. In nature, honey bee colonies organize their
nests with a consistent, three- dimensional spatial structure: a region of
cells densely filled with brood that is surrounded by cells containing pol-
len, and a region in the periphery of cells filled with honey, mostly in the
upper part of the nest. This spatial organization helps ensure that the
brood- nest region is kept at its proper temperature. It also helps increase
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the work efficiency of the nurse bees by ensuring that they (the primary
consumers of the pollen) have a ready supply of pollen near the brood.
Beekeeping manipulations that alter this nest organization—such as insert-
ing empty combs to reduce congestion in the brood nest—hamper brood-
nest thermoregulation and may disrupt other aspects of colony functioning
such as egg laying by the queen, brood- food production by the nurse bees,
and nectar storage by the food- storer (middle- aged) bees.
Difference 9: Colonies experience infrequent vs. sometimes frequent relo-
cations.
Whenever a colony is moved to a new location, as occurs in migratory
beekeeping, the foragers must learn the landmarks around their hive and
must discover new sources of nectar, pollen, and water. One study found
that colonies moved overnight to a new location had smaller weight gains
in the week following the move relative to control colonies already living
in the location.
Difference 10: Colonies are rarely vs. frequently disturbed.
We do not know how often wild colonies experience severe distur-
bances (e.g., attacks by bears, skunks, or yellow jacket wasps), but it is
probably rarer than for managed colonies, whose nests are often cracked
open, smoked, and manipulated. In one experiment that was conducted
during a honey flow, comparisons were made of the weight gains of colo-
nies that were and were not inspected. It found that colonies that were
inspected gained 20–30 percent less weight (depending on the degree of
disturbance) than control colonies on the day of the inspections.
Difference 11: Colonies deal with familiar vs. novel diseases.
Historically, honey bee colonies dealt only with the parasites and patho-
gens with whom they had long been in an arms race. Therefore, they had
evolved means of surviving with their agents of disease. Humans changed
all this when we spread the ectoparasitic mite Varroa destructor from eastern
Asia, small hive beetle ( Aethina tumida) from sub- Saharan Africa, and chalk-
brood fungus ( Ascosphaera apis) and tracheal mite ( Acarapis woodi) from
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Darwinian Beekeeping 283
Europe. The near- global spread of Varroa destructor alone has resulted in the
deaths of millions of honey bee colonies, both wild and managed.
Difference 12: Colonies have diverse vs. homogeneous pollen sources.
Many managed colonies are placed in agricultural ecosystems—for ex-
ample, vast almond ( Prunus amygdalus) orchards or huge fields of oilseed
rape ( Brassica napus)—where they experience low- diversity pollen diets
and relatively poor nutrition. The effects of pollen diversity have been
studied by comparing nurse bees given diets with monofloral pollens and
those given polyfloral pollens. In tests that used nurse bees infected with
the microsporidian parasite Nosema ceranae, it was found that the bees fed
with the polyfloral blend of pollens lived longer than those fed with mono-
floral pollens.
Difference 13: Colonies have natural diets vs. are fed artificial diets.
Some beekeepers feed their colonies protein supplements (pollen sub-
stitutes) to stimulate colony growth before pollen is available. This is done
to help meet the colony- size requirements of pollination contracts and to
produce larger honey crops. The best pollen supplements/substitutes do
stimulate brood rearing, though often not as well as real pollen. Colonies
that are nutritionally stressed by a lack of pollen (or by a poor artificial
diet) produce workers that have reduced longevity, an early onset of forag-
ing, and a shortened period of functioning as a forager.
Difference 14: Colonies are not exposed vs. are exposed to novel toxins.
The most important novel toxins to which honey bees are exposed are
insecticides and fungicides, substances for which the bees have not had
time to evolve detoxification mechanisms. Honey bees are now exposed
to an ever- increasing range of insecticides and fungicides that can syner-
gize in causing harm to the bees.
Difference 15: Colonies are not treated vs. are treated for diseases.
When we treat our colonies for diseases, we interfere with the host-
parasite arms race between Apis mellifera and its pathogens and parasites.
Specifically, we weaken natural selection for disease resistance. It is no
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surprise that most managed colonies in North America and Europe possess
little resistance to Varroa mites, and that there are populations of wild colo-
nies on both continents that have evolved strong resistance, as discussed in
chapter 10. Treating colonies with miticides and antibiotics may also in-
terfere with the microbiomes of a colony’s bees.
Difference 16: Colonies are not managed vs. are managed as sources of honey
and pollen.
Colonies managed for honey production are housed in large hives, so
they are more productive. However, they are also less apt to reproduce by
swarming, w
hich means there is less scope for natural selection for healthy
colonies—that is, for the healthiest colonies to be most successful in pass-
ing on their genes. Also, the immense quantity of brood in large- hive colo-
nies renders them more vulnerable to population explosions of Varroa
mites and the other agents of honey bee disease that reproduce in brood.
Harvesting pollen makes it harder for colonies to acquire a complete diet.
Difference 17: Combs are not moved vs. are moved between colonies.
Moving combs from one colony to another, especially combs that have
been or are being used for rearing brood, is an extremely effective way to
spread diseases between colonies, and yet it is commonly done. Sometimes
it is done to equalize colony strength, other times to give colonies addi-
tional combs in which to store honey. Whatever the purpose, it greatly
increases the spread of diseases between colonies.
Difference 18: Honey cappings are recycled by bees vs. are harvested by bee-
keepers.
Removing beeswax from a colony when uncapping honey combs for
harvesting honey imposes a serious energetic burden. The weight- to-
weight efficiency of beeswax synthesis from sugar is at best about 0.20, so
every kilogram (ca. 2 pounds) of wax taken from a colony costs it some 5
kilograms (ca. 10 pounds) of honey that is not available for other purposes,
such as brood rearing and winter survival. Besides the energetic cost of
beeswax synthesis, there are the wear- and- tear costs on the worker bees
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Darwinian Beekeeping 285
involved in the wax synthesis; the bees expend a portion of their lifetime
work capacity in producing wax rather than performing other tasks. This
situation is analogous to a human factory in which the total cost of making
something involves wear- and- tear (depreciation) costs on the machinery,
not just the energy costs of powering the machinery. The way of harvesting
honey that is the most energetically burdensome to the bees is removal of
entire combs filled with honey (cut comb honey or crushed comb honey).
It is less burdensome to produce extracted honey, since this removes just
the top layer of wax cappings.
Difference 19: Colonies are allowed vs. are not allowed to choose the larvae
for rearing queens.
When we humans graft one- day- old larvae into artificial queen cups for
rearing queens, we prevent the bees from choosing which larvae will de-
velop into queens. One study has found that in emergency queen rearing,
the bees do not choose larvae at random and instead favor those of certain
patrilines. It may be the case, too, that the bees exercise choice that is
based on larval health, which is a sign of the overall vigor of the developing
bee.
Difference 20: Drones are allowed vs. are not allowed to compete fiercely
for matings.
In bee- breeding programs that use artificial insemination, the drones
that provide the sperm do not have to prove their vigor by competing
among dozens or hundreds of other drones to mount a flying queen and
inject his sperm into her oviducts. This lack of drone- drone competition
weakens the sexual selection for drones possessing genes for excellent
health and flight ability.
Difference 21: Drone brood is not removed vs. is removed from colonies for
mite control.
The practice of removing drone brood from colonies partially castrates
them and so interferes with natural selection for colonies that are healthy
enough to invest heavily in rearing and supporting drones.
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SUGGESTIONS FOR DARWINIAN BEEKEEPING
Beekeeping looks different when viewed from an evolutionary perspec-
tive. We have seen that honey bees have lived independently of human
beings for millions of years and that throughout this immense span of time
their biology was tuned by natural selection to favor two things: colony
survival and colony reproduction. We have also seen that ever since hu-
mans started keeping bees in hives several thousand years ago, we have
been disrupting the close fit that previously existed between these bees
and their environment. We have done so in two general ways: 1) by moving
honey bee colonies to geographic locations to which they are not well
adapted, and 2) by manipulating their lives in ways that boost their produc-
tion of things that we value: honey, beeswax, pollen, royal jelly, and
pollination.
What can a beekeeper do now to help his or her honey bees live with a
better fit to their environment, hence with less stress and better health?
The answer depends on the individual beekeeper’s aims. A backyard bee-
keeper who enjoys supervising a few colonies mainly for the pleasures of
bee watching, and who is happy to put the bees’ needs before his or her
own, has many ways to pursue bee- friendly beekeeping. In contrast, a
commercial beekeeper who manages hundreds or thousands of colonies
to earn a living by producing honey crops and fulfilling pollination con-
tracts has fewer options for pursuing a kinder and gentler approach to the
craft. What follows is a list of suggestions. You can think of the items on it
as ingredients for devising a personal recipe of Darwinian beekeeping, one
that is realistic given your aims and opportunities as a beekeeper.
1. Work with bees that are adapted to your location. For example, if you live
in the northeastern United States, then either rear queens from your har-
diest survivor colonies or buy queens (or nucleus colonies) produced from
stock that has proven itself by thriving in this region despite its long, harsh
winters. If you do not want to rear your own queens and you do not have
a local queen producer, but you do have wild colonies living in your area,
then you can easily get locally adapted stock by capturing swarms pro-
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Darwinian Beekeeping 287
duced by the wild colonies. The most efficient way to do so is to set out
bait hives. This approach will work best if you live in a place that is not
crowded with fellow beekeepers, some of whom might be purchasing
queens shipped in from far away.
2. Space your hives as widely as possible. Where I live in central New York
State, the wild colonies living in the forests are spaced roughly 800 meters
(0.5 miles) apart. We have seen in chapter 10 that wild colonies benefit
from this wide separation, but of course such a wide spacing of colonies is
impossible for most beekeepers. Fortunately, we have also seen in chapter
10 (Fig. 10.6) that spacing colonies just 30–50 meters (100–160 feet)
apart greatly reduces the likelihood of drifting of drones—and probably
also workers—among colonies and thus the spreading of disease.
3. House your colonies in small hives. Consider providing just one deep hive
body for a colony’s brood nest and then providing it with just one medium-
depth honey super over a queen excluder for securing a modest honey
crop. Your ho
ney harvest will be smaller than it would be if you were to
supersize the colony by giving it two deep hive bodies for its brood nest
and then putting a tall stack of honey supers on top. You will, however,
reduce the colony’s problems with parasites and pathogens, especially Var-
roa destructor and the viruses it vectors, as discussed in chapter 10 (Fig.
10.8). This is especially true if you allow your colonies to swarm. Swarm-
ing removes many mites from a colony, and it creates a break in the colo-
ny’s brood rearing that deprives the mites of the cells of capped brood that
they need for their reproduction.
4. Roughen the inner wall surfaces of your hives, or build them of rough- sawn
lumber. This will stimulate your colonies to cover the walls inside your
hives with propolis and so build antimicrobial shrouds around their combs.
5. Use hives whose walls provide good insulation. These might be hives built
of thick lumber, or they might be hives made of plastic foam. An important
subject for future research is how much insulation is best for colonies liv-
ing in different climates and how best to provide it.
6. Position hives high off the ground. This is not always feasible but may be
doable if you have a porch or a flat roof where you can keep your hives.
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Another important topic for research is how exactly it is that entrance
height affects colony success in different settings and climates. Is it the case
that colonies living where winters are snowy benefit greatly from having
their entrances high off the ground because this helps their workers avoid
crashing onto the snow when they fly out to make wintertime cleansing
flights?
7. Allow colonies to maintain 10–20 percent of the comb in their hives as drone
comb. Doing so will give your colonies the opportunity to rear plentiful
drones, and this can help improve the genetics in your area (if you are not
treating your colonies). Drones are costly, so it is only the healthiest and
strongest colonies that can produce legions of drones. Please note: plenti-
ful drone brood in a colony fosters the reproduction of the Varroa mites by
providing them with their ideal host, so providing plentiful drone comb
also requires diligent monitoring of the mite levels in your colonies and