The Lives of Bees

by Thomas D Seeley

The first is the bees’ predilection for nesting in cavities the size of a water

  pot or large basket (20–40 liters/5.3–10.6 gallons). It may be, therefore,

  that the first dwelling places of the honey bee located near human homes

  were empty pots and overturned baskets that had been left lying outdoors

  and were occupied by wild swarms. This scenario seems especially likely

  in the grassland regions of the Fertile Crescent, where bee forage must

  have been abundant but natural nesting cavities were probably scarce. If

  this hypothesis is correct, then it was the honey bees themselves, not

  human beings, that took the first step toward having bee colonies reside in

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  man- made structures (hives) arranged in clusters (apiaries) near human

  dwellings.

  The second, and probably more important, behavioral trait of honey

  bees that predisposed them to domestication is described by Lorenzo L.

  Langstroth in the second chapter of his 1853 manual for beekeepers, Lang-

  stroth on the Hive and the Honey- Bee. Its title is intriguing: “The honeybee

  capable of being tamed or domesticated to a most surprising degree.” Here

  Langstroth explains to prospective beekeepers that even though honey

  bees can be as fiercely defensive of their nests as hornets, they are decid-

  edly different from hornets in that they are not always highly defensive. He

  goes on to explain that worker honey bees are amazingly reluctant to sting

  once they have filled their crops (honey stomachs) with honey (Fig. 4.1),

  and that it is this striking feature of their behavior that makes possible the

  taming of these otherwise fearsome stinging insects.

  There are two distinct contexts in which it is adaptive for worker bees

  to stuff themselves with honey and become averse to stinging. One is when

  they are in a swarm. Swarming bees tank up with honey—indeed, they

  nearly double their body weight in doing so—before they leave their old

  home in order to be fully energized for the flight to their new dwelling

  place and for the work of fitting it out with beeswax combs. But why are

  these honey- laden bees so reluctant to sting? The answer is simple: the act

  of stinging is fatal for a worker honey bee, and a swarm needs as many

  worker bees as possible once it has moved into its new nest site. As we shall

  see in chapter 7, the greater the number of bees in a swarm, the higher the

  probability the colony will survive its perilous first winter in its new home.

  The second circumstance in which it is highly adaptive for worker bees

  to engorge on honey and then refrain from stinging is when their home is

  threatened by fire, a danger they sense by smelling smoke. A field study

  recently conducted by Geoff Tribe, Karin Sternberg, and Jenny Cullinan

  has revealed how colonies of the Cape honey bee ( Apis mellifera capensis) in

  South Africa benefit from imbibing honey and becoming passive when they

  smell smoke. Seven days after a wildfire incinerated a 988- hectare (2,441-

  acre) swath of the Cape Point Nature Reserve, these investigators in-

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  Are Honey Bees Domesticated? 83

  Fig. 4.1. Worker bees filling up on honey.

  spected 17 nesting sites within the charred landscape that they knew had

  been occupied by wild colonies before the fire. Each colony occupied a

  rock- walled cavity located either beneath a boulder or in a cleft within a

  rocky outcrop (Fig. 4.2). The research team discovered that all 17 colonies

  were still alive, even though several had suffered partial destruction of

  their nests: some melting of the propolis “firewall” at the nest entrance and

  (less often) of the beeswax combs deeper in the nest cavity. Evidently, the

  bees had filled up with honey upon smelling the smoke, had retreated as

  deeply as possible into their fireproof nest cavities, had survived the wild-

  fire, and were sustaining themselves on the honey they had cached in their

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  Fig. 4.2. Wild honey bees in South Africa flying from their undamaged nest

  shortly after wildfire has swept past their home in the rocks. The heat of the fire

  has triggered the scorched, brushy plants ( Leucadendron xanthoconus) around the

  nest to open their orange- brown seed heads.

  bodies. A week or so later, plants known as fire- ephemerals would sprout

  and start to bloom, so soon these bees would be able to resume foraging.

  This investigation of wild honey bee colonies surviving a wildfire shows

  us how the bees’ engorgement response to smoke is adaptive for the bees

  living in a fire- prone region of South Africa. What it reveals, however, is

  a bit different from the standard explanation for why honey bees fill up

  on honey and become quiet when they smell smoke: to prepare for aban-

  doning the nest to escape the fire. I think the standard explanation is probably

  incorrect, for I suspect it is unlikely that a colony threatened by fire can

  successfully evacuate its nest site and fly off through flames and smoke,

  especially since its queen is apt to be gravid and therefore a perilously

  clumsy flier.

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  One wonders, when did humans discover the magical potency of a few

  puffs of smoke to pacify thousands of irascible bees? The beekeeper blow-

  ing smoke toward a hive in Figure 3.3 shows us that 4,000- plus years ago

  Egyptian beekeepers already knew this trick for calming their colonies. It

  is possible, though, that the power of smoke to disarm a honey bee colony

  had been stumbled upon much earlier, indeed long before the origins of

  Egyptian beekeeping, back when humans were still just bee hunters, not

  yet beekeepers. Archaeological evidence indicates that the controlled use

  of fire was universal among humans some 120,000 years ago.

  ARTIFICIAL SELECTION WITH HONEY

  BEES IS BARELY 100 YEARS OLD

  We humans boost the productivity of our domesticated animals, cultivated

  crops, and useful microbes in two general ways: by changing their genes

  and by manipulating their environments. I am reminded of this fact when-

  ever I drive through the rich farmlands north of Ithaca, a place that truly

  is a land “flowing with milk and honey.” Dairy farms and bee yards are

  common here, and seeing them turns my thoughts to what dairy farmers

  and beekeepers now do to make their livestock as profitable as possible.

  Over the last 50 years, dairy farmers have boosted their production of

  milk per cow both by changing the genetics of their cows—black- and-

  white Holsteins have replaced the once familiar Dutch Belteds and brown

  Jerseys—and by transforming their living conditions. For example, dairy

  cows no longer spend summer days grazing in grassy fields. Most now live

  year- round in individual stalls or group spaces (freestalls) inside immense,

  open- sided shelters, where they are fed protein- rich corn and alfalfa, and

  often antibiotics and hormones, all to pump up their milk production. Sex

>   is also a thing of the past for these cows. Calves are separated from their

  mothers within days of birth, and when a mother cow’s milk production

  slackens, she is impregnated artificially using semen from a bull selected

  for his record of siring cows that are first- rate milkers. Once “mated,” the

  cow is on course for another round of work as a unit of production on the

  factory farm.

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  Honey bees share with dairy cows the fate of being economically im-

  portant animals that are thoroughly manipulated by humans to boost their

  productivity. But unlike Holstein cows, which require daily care from hu-

  mans to thrive, honey bees remain capable of living on their own. Why is

  this? Specifically, why is it that we humans have not altered the genetics of

  honey bees through breeding to the point where they, like dairy cows,

  need steady help from us to survive? The answer is not that honey bees lack

  the critical ingredient of all breeding programs: differences among indi-

  viduals in traits that are heritable (have a genetic basis) and have a high

  economic value. In bee breeding, the colony is the individual, and colonies

  vary in many ways that reflect their genetic differences and are economi-

  cally important. These include honey production, pollen collection, gen-

  tleness, proclivity to swarm, propolis collection, wintering ability, and

  disease resistance.

  What is it, then, that has prevented beekeepers, until recently, from

  breeding their colonies to have high honey production, low defensiveness,

  strong disease resistance, or some other desired trait? The answer is mainly

  one thing: beekeepers lack tight control over the reproduction of their

  colonies. An animal breeder shapes the future generations of his stock by

  controlling their reproduction, letting only those individuals with desir-

  able traits produce offspring. Until the late 1800s, however, beekeepers

  could not control which of their colonies had the greatest reproductive

  success, that is, the greatest success in producing the queens of the future

  colonies and the drones that would inseminate these queens. Beekeepers

  had to leave these matters up to the bees, and therefore up to natural selec-

  tion. What beekeepers needed were ways to favor the reproduction of

  certain queens and certain drones, namely those from their best colonies,

  so that they could promote the genetic success of their best bees.

  This situation began to change in the mid- 1800s following Langstroth’s

  invention of the movable- frame hive (Fig. 3.8). Hives of his design made

  it possible for beekeepers to examine their colonies without seriously

  disrupting them and to take out swarm cells—queen cells in colonies

  preparing to swarm—from their best colonies to produce high- quality

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  queens for requeening poor colonies and starting new colonies to enlarge

  their apiaries. However, it was not until the invention of efficient methods

  of artificial queen rearing by Gilbert M. Doolittle, which he reported

  widely in his 1889 book Scientific Queen- Rearing, that it became possible

  for beekeepers to begin breeding strongly from their best colonies. Usu-

  ally the virgin queens reared from these superior colonies mated freely, in

  which case the breeding was accomplished without artificial selection

  among drones. But sometimes the selected virgin queens were taken to

  remote places (e.g., islands or high mountain valleys) stocked with se-

  lected colonies producing drones, in which case the breeding also included

  some artificial selection of the drones. Fully controlled bee breeding based

  upon strong artificial selection of both queens and drones only began to

  become possible in the 1920s with the invention by Lloyd R. Watson (for

  his PhD thesis at Cornell University) of the tools and techniques for the

  artificial insemination of queen bees (Fig. 4.3). Watson was skilled in de-

  signing, making, and using micromanipulators, and this led him to refer to

  artificial insemination of queen honey bees as “instrumental insemination,”

  the term that is generally used today by bee breeders. It was not until the

  1940s, however, once Harry H. Laidlaw had refined the procedures and

  syringes for injecting semen deep into a queen bee’s oviducts, so that the

  spermatozoa can migrate easily into her spermatheca, that the artificial

  insemination of queen bees became reliable. At last, beekeepers had com-

  plete control of who inseminated their selected queens and so could con-

  trol fully the genetics of their new colonies.

  An early example of well- controlled bee breeding comes from a pro-

  gram that bred for resistance to American foulbrood (AFB), a disease of

  developing bees caused by the bacterium Paenibacillus larvae. Because AFB

  spreads easily between colonies (mainly through robbing), it is the most

  virulent of the brood diseases of honey bees. The program of breeding for

  AFB resistance began in 1934 when O. Wallace Park and F. B. Paddock,

  entomologists at Iowa State College, and Frank C. Pellet, an editor of the

  American Bee Journal, began a search for colonies that beekeepers judged to

  have some resistance to AFB. In 1935, they assembled, in a testing yard in

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  Fig. 4.3. Lloyd R. Watson in 1928 showing the position of the operator while

  conducting an instrumental insemination of a queen bee with the original model

  of the apparatus. Both elbows are on the desk, and the left hand is steadied against

  the stage of the microscope.

  Iowa, 25 such colonies drawn from various parts of the United States. Each

  colony was tested for resistance by the insertion into one of its brood

  combs of a rectangle of comb containing approximately 200 cells, of

  which 75–100 contained AFB scales—the dried remains of larvae killed

  by AFB. The colonies responded by either removing the introduced comb,

  cleaning out the infected cells in it, or doing nothing. Most of the colonies

  contained AFB- killed brood at the end of the summer, but seven (28%)

  showed no signs of the disease and were considered resistant. The next step

  in this breeding program came in 1936, when these investigators estab-

  lished a semi- isolated apiary in the middle of a 100- square- kilometer (ca.

  40- square- mile) citrus orchard in Texas, in which queens and drones were

  reared from the resistant colonies and allowed to mate. Twenty- seven

  colonies headed by these queens were then given a test for AFB resistance

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  100

  r’s end 75

  50

  Percent of colonies

  25

  25 27 114 111 148 89 59 90 89 55 66 101

  disease-free at summe

  1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946

  Fig. 4.4. Striking progress in breeding for resistance to American foulbrood.

  The percentage of colonies that remained diseas
e- free after being inoculated

  with AFB spores increased over 12 years of selective breeding. The numbers

  within the bars indicate the number of colonies used each year. The asterisks

  indicate years in which the queens’ matings were controlled by instrumental

  insemination.

  using the same inoculation- comb procedure used the previous year. Nine

  colonies (33%) showed no sign of AFB when carefully inspected at the end

  of the summer. Over the next 10 years, this process of rearing and mating

  (in semi- isolation) queens and drones from the most resistant colonies was

  repeated, and impressive progress was made in raising the percentage of

  resistant colonies (Fig. 4.4). This was especially so in the years starting in

  1944, when the queens were instrumentally inseminated to prevent out-

  crossing due to incomplete isolation at the mating yard; the proportion of

  AFB- resistant colonies climbed to nearly 100 percent.

  The striking results from this program of artificial selection for AFB

  resistance by O. Wallace Park and colleagues in Iowa, along with later

  studies on the genetics of this resistance by Walter C. Rothenbuhler in

  Ohio, are impressive examples of what can be done in bee breeding. This

  initial work on breeding for resistance to brood disease has been devel-

  oped further by selection programs for resistance to Ascosphaera apis, the

  fungus that causes chalkbrood, and to tracheal mites ( Acarapis woodi) and

  Varroa destructor mites. All these programs have focused on breeding for

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  hygienic behavior—the removal and disposal of diseased brood (larvae

  and pupae)—because multiple studies have shown that better hygienic

  behavior endows colonies with greater resistance to chalkbrood and mites,

  just as it does to American foulbrood. Hygienic behavior is also an attrac-

  tive target for selective breeding because it is a colony- level trait that is

  easily measured. A comb containing brood is removed from a hive, a small

  area of this brood comb is frozen with liquid nitrogen, the comb is re-

  turned to the hive, and then the removal of the freeze- killed brood is

  measured after fixed time intervals. Colonies that remove it within 24

  hours are considered hygienic; those that take longer are considered non-