The Lives of Bees
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Colony Reproduction 183
more expansive and responsive foraging effort. The mystery of exactly
how increasing the genetic diversity of a colony’s workforce makes it more
effective has been carefully investigated by Heather R. Mattila, starting
when she was a postdoctoral student at Cornell. One line of her investiga-
tions focused on the foraging abilities of colonies, and to study this she
compared the activities of individual forager bees in multiple- patriline and
single- patriline colonies, that is, colonies whose queens were instrumen-
tally inseminated with either a blend of semen collected from 10 drones
or the same volume of semen collected from just 1 drone. Heather found
that the multiple- patriline colonies benefited from having more social fa-
cilitators of foraging—that is, worker bees who became engaged as forag-
ers (and waggle dancers) early in the day and thereby galvanized their
colony’s foraging effort. These high- participation bees belonged to only a
handful of the patrilines in the multiple- patriline colonies and were often
absent from the single- patriline colonies.
Until recently, all the estimates of the mating frequency of queens in
the European subspecies of Apis mellifera—living either in Europe or North
America—were based on samples of worker bees collected from managed
colonies living in apiaries, that is, from colonies headed by queens that
probably conducted their mating flights where drones were ultra- abundant.
I wondered whether these estimates of queen mating frequency apply to
queens living in the wild, where colonies are widely spaced. Do queens
have lower mating frequencies when the colony density is lower and po-
tential mates may be less plentiful? To answer this question, I worked with
two colleagues—David R. Tarpy at North Carolina State University and
Deborah A. Delaney at the University of Delaware—to determine the
mating frequencies of the queens in colonies living in the Arnot Forest.
The first step in this study was taken in August 2011, when I and a Cor-
nell undergraduate student, Sean R. Griffin, located 10 bee- tree colonies
living in or just outside of the Arnot Forest (Fig. 7.11), by using the tech-
nique of bee lining, described in chapter 2. To collect a sample of at least
100 workers from each bee- tree colony, we captured bees from our feed-
ing station. We only captured these bees once we had gotten within 100
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184 Chapter 7
1400
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Fig. 7.11. Map of the Arnot Forest and adjacent lands showing the locations of
the 10 bee- tree colonies located in August 2011 and of the two nearest apiaries
outside of the Arnot Forest.
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Colony Reproduction 185
meters (330 feet) of the tree the colony occupied, at which point our
feeding station was totally dominated by foragers from the nearby colony
(as confirmed by subsequent genetic analyses).
Because we wanted to compare the mating frequencies of our wild colo-
nies’ queens to those of the nearest managed colonies’ queens, we also
collected, in August 2011, approximately 100 workers from each of 20
managed colonies, 10 in each of the two apiaries nearest the Arnot Forest.
Apiary 1 was located only 1.0 kilometer (0.6 mile) from the Arnot For-
est’s southwestern boundary (see Fig 7.11) and had been newly established
by a commercial beekeeper in May 2011. The colonies in this apiary con-
tained young queens purchased that spring from a queen breeder in Cali-
fornia, so we were confident that the workers sampled from its 10 colonies
provided information on the mating frequency of commercially produced
queens. The other apiary (apiary 2) was located 5.2 kilometers (3.2 miles)
from the northwestern corner of the Arnot Forest. The same commercial
beekeeper that had established apiary 1 in May 2011 had established apiary
2 in the early 2000s, and from time to time he gave the colonies in apiary
2 new queens purchased from the same queen breeder in California that
had produced the queens in apiary 1. It was handy to have these two apiar-
ies near the Arnot Forest, for they enabled us to compare the mating fre-
quencies of wild- colony and managed- colony queens living in the same
general location. It was, however, also dismaying to find apiary 1 located
only 1 kilometer from the southwestern boundary of the Arnot Forest, for
its presence had the potential to alter the genetics of the bees in this forest.
My dismay was short- lived, however, because a black bear destroyed apiary
1 in November 2011, and ever since then the site has been abandoned.
When David Tarpy and Deborah Delaney performed a paternity analysis
on 1,089 of the worker bees that I had collected from the 30 colonies—on
average, 36.3 individuals per colony—they found no significant differ-
ences in mean number of drone fathers (sperm donors) per queen among<
br />
the three groups of queens (Fig. 7.12). The mean mating frequencies of the
apiary 1 queens (19.8 drones) and the apiary 2 queens (16.6 drones) were
not statistically distinguishable from those of the Arnot Forest queens (15.9
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186 Chapter 7
s 20
15
10
5
Number of drone father
Apiary 1 Apiary 2
Arnot
forest
Fig. 7.12. Average mating frequencies of 10 honey bee queens sampled from the
three groups: the two apiaries nearest the Arnot Forest and the population of
wild colonies living in this forest. The queens in the apiary 1 colonies had been
reared and had mated in California, within the operation of a large, commercial
queen producer.
drones). These results show that queens living in wild colonies that are
broadly dispersed do not necessarily mate with fewer drones than queens
living in managed colonies that are crowded together. This is because even
where colonies are spread thinly across the countryside, their queens and
drones come together at a few special sites—drone congregation areas—
when it is time to mate. In short, the low density of colonies in a wild
population does not give rise to a low density of drones in the places
where queens are inseminated. This is not so surprising when you consider
that before humans started managing the lives of honey bees, their colo-
nies lived widely dispersed, and so natural selection must have strongly
favored queen bees and drones with the mysterious ability to fly off and
find individuals of other colonies to tend to the affairs of sex.
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8
FOOD COLLECTION
Much have I marvelled at the faultless skill
With which thou trackest out thy dwelling- cave,
Winging thy way with seeming careless will
From mount to plain, o’er lake and winding wave.
—Thomas Smibert, “The Wild Earth- Bee,” 1851
We generally think of a honey bee colony as a family of bees living inside
a bee hive or a hollow tree. A moment’s reflection will disclose, however,
the important fact that during the daytime many of the bees in a colony
are dispersed far and wide over the surrounding countryside, where they
toil to gather their colony’s food. To accomplish this, each forager bee flies
as far as 14 kilometers (8.7 miles) to a patch of flowers, gathers a load of
nectar or pollen (or both, Fig. 8.1), and then flies home, where she quickly
off- loads her food and then heads out on her next collecting trip. On a
typical day, a colony will field several thousand worker bees, or about one-
third of its members, as foragers. Thus, in acquiring its food, a honey bee
colony functions as a large, diffuse, amoeboid entity that can extend itself
over great distances and in multiple directions simultaneously to exploit a
vast array of food sources. To succeed in gathering the pollen and nectar it
needs, a colony must closely monitor the food sources within its environ-
ment, and it must wisely deploy its foragers among these sources so that
its food is gathered efficiently, in sufficient quantity, and with the correct
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188 Chapter 8
Fig. 8.1. Worker bee flying home bearing loads of yellow- green pollen on her
hind legs and a load of nectar in her crop (honey stomach). That she is carrying
a nectar load is indicated by the distension and translucence of her abdomen.
nutritional mix. The colony must also properly apportion the food it gath-
ers between present consumption and storage for future needs. Moreover,
it must accomplish all these things in the face of constantly changing condi-
tions, both outside the nest as foraging opportunities come and go, and
inside the nest as the colony’s nutritional needs change with the seasons.
In this chapter, we will see how a colony living in the wild meets these
challenges.
THE ECONOMY OF A WILD COLONY
Besides fresh air, a colony of honey bees needs just four resources to sus-
tain itself: pollen, nectar, water, and tree resin (Fig. 8.2). Pollen is the most
nutritious item on the bees’ short shopping list. It provides the amino
acids, fats, minerals, and vitamins that immature bees need to develop
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Food Collection 189
Resin
Water
Flower patches
source
source
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P
P
P
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W
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Pollen
Nectar
Water
Pollen
Honey
Receiver
cells
cells
bees
Evaporation
Nurse
Queen
Forager
Foraging
bees
bees
costs
Food and
heat
Eggs
Larvae
Heat loss
Mortality
Fig. 8.2. The flow of materials in a honey bee colony on a summer day. The width
of each arrow is proportional to the amount of matter flowing along its route.
Matter accumulates in the growing larvae, to boost the colony’s population, and
in the pollen cells and honey cells, to build up its reserve supplies of pollen and
honey for rainy days and winter.
properly and that adult bees need to keep their bodies working properly.
The nurse bees in a colony, for example, rely on finding cells stocked with
pollen near the brood nest, for if their diet lacks pollen, then their brood-
food (hypopharyngeal) glands will atrophy and they will be unable to
nourish their colony’s young. The nurse bees’ need for pollen to be stored
near the brood explains why, when you peer inside a glass- walled observa-
tion hive and watch a pollen forager that has just come home with two
balls of brightly colored pollen on her hind legs, you see that she looks
along the margins of the brood nest to find a cell in which to off- load her
pollen. You see too that once she finds a suitable storage cell, she stands for
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190 Chapter 8
about 10 seconds with the tip of her abdomen poking into this cell, briskly
rubbing her hind legs together to rake off her pollen loads. This care in
unloading, performed by all the foragers engaged in pollen collection,
creates a neat band of pollen- filled cells around the brood nest.
Other foragers arriving home do not carry pollen loads on their hind
legs but instead land at the nest entrance with conspicuously swollen ab-
domens. If you snag one of these bees before she disappears inside the nest,
calmly hold her by the wings and then gently compress her abdomen with
forceps, you will see her disgorge a droplet of clear or pale yellow liquid.
Analysis of its composition will usually reveal
that it is a concentrated solu-
tion of sugars—mainly glucose, fructose, and sucrose—hence it is nectar,
the bees’ principal source of carbohydrates. However, not all the bees that
return home with bulging abdomens are nectar foragers; a small percent-
age carry in cargoes of nearly pure water. These are water collectors, re-
turning from a puddle, stream, or whatever water source is handy. Both
nectar foragers and water collectors regurgitate the contents of their crops
(honey stomachs) to bees working inside the nest (Fig. 8.3). To do this, the
bee off- loading liquid opens her mandibles widely and disgorges a droplet
of liquid that sits on the base of her folded proboscis (tongue). The bee
receiving the liquid extends her proboscis to full length and quickly drinks
the fluid. The recipients of the nectar and water are usually middle- aged
bees. Those that accept nectar (nectar receivers) distribute some of this
fresh food to others for immediate consumption, but they process most of
it into honey for future consumption. Those that accept water (water re-
ceivers) will either spread it over the combs to cool the nest or distribute
it among the nurse bees. The collection of water for the nurse bees occurs
most often in early spring, when the colony is subsisting on honey and
stored pollen, and the colony’s nurse bees need water to maintain their
water balance as they prepare suitably dilute food for the colony’s larval
brood.
Pollen, nectar, and water are the substances most commonly gathered
by a colony’s foragers. But during late summer and early fall, if you keep
a close watch at a hive’s entrance, you will also spy a few bees returning
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Food Collection 191
Fig. 8.3. A nectar forager with bulging abdomen (right), having returned to her
nest, regurgitates her nectar load to a food- storer bee (left), which has inserted
her tongue between the mouthparts of the forager.
home with shiny brown loads of tree resin stuck in their pollen baskets
(Fig. 5.15). As discussed in chapter 5, the bees jam this gluey material into
cracks and small holes in the walls of their nest cavity, making their home
more weathertight and easier to defend. We also saw that they use this
resin to coat the walls of their nest cavity because it has antimicrobial
properties that promote colony health.
What follows now is a quantitative look at a colony’s collection of nec-
tar and pollen, with emphasis on the total amounts of these two materials
that a colony consumes over a year. This overview shows that a colony’s
foraging operation is a massive enterprise, even for a relatively small col-