The Lives of Bees

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The Lives of Bees Page 7

by Thomas D Seeley


  My concern for the wild colonies was deepened by three things that

  suggested that this population of colonies had indeed been killed off.

  First, starting in the mid- 1990s, I had difficulty finding honey bees on the

  dandelion flowers that carpet the lawns and fields around Ithaca in late

  April and early May. Not good news. Second, also in the mid- 1990s, I

  noticed that I was receiving very few phone calls asking me to collect a

  swarm that had settled on a tree or building around the Cornell campus,

  in contrast to the 1980s, when I would get several of these swarm calls

  each summer. Definitely bad news. And third, in 1995, a paper by two

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  highly reputable honey bee researchers at the University of California at

  Davis, Bernhard Kraus and Robert E. Page Jr., reported that Varroa de-

  structor “has had a devastating effect on the demography of feral bee colo-

  nies throughout California.” They also suggested that “there is no wide-

  spread, general preadaptation to Varroa mites in honey bees in California.”

  Truly dreadful news.

  My concerns rose still higher when, in June 1997, I read an article in

  one of the beekeeping magazines, the American Bee Journal, written by Dr.

  Gerald Loper, a staff scientist at the USDA’s Honey Bee Research Labora-

  tory in Tucson, Arizona. In the article, Loper reported his findings from a

  long- term study he was conducting on a population of wild honey bee

  colonies living in the mountains of the Sonoran Desert north of Tucson.

  Starting in 1987, he had located 247 nesting sites (mostly rock crevices)

  that were or had been occupied by wild colonies at one time or another.

  He knew from genetic analyses that all these colonies were European

  honey bees; indeed, 68 percent of the colonies had the mitochondrial

  DNA haplotype of the dark European honey bee, Apis mellifera mellifera.

  Each year, he inspected the sites in early March to assess the colonies’

  survival over winter, and he checked them again in June to assess the re-

  sults of their swarming. Where possible, he also collected samples of

  worker bees from these colonies—by breathing into their nest entrances

  and then netting 50–150 bees—to inspect them for tracheal mites ( Acara-

  pis woodi) and Varroa mites.

  The findings that Gerald Loper reported painted a somber picture: this

  population of wild European honey bee colonies was decimated by the

  arrival of both types of mites, but especially Varroa destructor (Fig. 2.11). In

  1992 and 1993, before Varroa arrived in the study area, 120–160 colonies

  had been living in the 247 nesting sites, but over the period 1994–1996,

  during which time nearly every colony became infested with Varroa, the

  number of occupied sites plummeted, leaving only 12 colonies still alive

  in March 1996. This population of wild colonies would perhaps have died

  out if Africanized honey bees had not begun to infiltrate it, starting in

  1995. By the late 1990s, it was starting to grow back, and today it is again

  thriving. Reading this paper left me with mixed feelings. I was thoroughly

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  Bees in the Forest, Still 47

  160

  Africanized honey bees

  become numerous

  120

  80

  alive in Spring 40

  Number of colonies

  100

  mites 75

  rroaVa 50

  25

  Percent of colonies

  infested with

  1992 1993 1994 1995 1996 1997 1998 1999 2000

  Fig. 2.11. Results of surveys of a population of wild colonies living in the

  mountains north of Tucson, Arizona. Tracheal mites spread through the area in

  1991– 1993, and Varroa mites arrived in 1993. The population’s genetics switched

  from mainly European to mainly Africanized bees in 1997– 1998.

  impressed by Loper’s long- term study of this population of wild honey

  bees living in the mountains of southern Arizona, but I was also deeply

  dismayed by its grim report of a population of wild colonies of European

  honey bees collapsing soon after the arrival of Varroa destructor.

  Given Gerald Loper’s findings from Arizona, together with what I was

  seeing firsthand around Ithaca, I believed in the early 2000s that the wild

  colonies of honey bees probably had vanished from the forests south of

  Ithaca. And as someone who cannot live without wild things, I mourned

  their passing. At the same time, however, the inner voice of curiosity kept

  posing a question: Is it really the case that the wild colonies are all gone? My

  curiosity feeds me many questions, far more than I can tend to, so most of

  them get left aside, but I could not ignore this one about the wild honey

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  bees, for nearly at my doorstep lay a unique resource from which I could

  seek a solid answer: the honey bees of Arnot Forest. I realized that this

  research forest was the one place in all eastern North America for which

  we had solid, baseline information about the abundance of wild colonies

  before Varroa destructor had set foot in this continent, thanks to the census

  of the wild colonies living in this forest that Kirk Visscher and I had made

  back in 1978. If I repeated this work, would I find some survivor wild

  colonies, or would I confirm their supposed extinction? I knew that I

  needed to find out, and in 2002 I returned to the Arnot Forest, taking steps

  to conduct this second census in a manner as close as possible to the first

  one. One was to make my census in the same season as before: from mid-

  August to late September. Another was to conduct the census in the same

  way as before: using the methods described by George H. Edgell in his

  charming book, The Bee Hunter.

  I began the second census on the afternoon of 20 August 2002, in a field

  of goldenrod ( Solidago canadensis) just inside the northeastern entrance to

  the Arnot Forest. This was the same season when I had begun my three

  weeks of bee hunting for the first census, back on 26 August 1978. The day

  was sunny and hot, and although no rain had fallen for several weeks, many

  of the goldenrod plants had unfurled their bright yellow inflorescences, so

  things looked perfect for me to find bees. But would I find any? I expected

  the answer would be no. As I climbed from my truck, I figured that I would

  probably spend the afternoon tromping around looking for foraging honey

  bees, not find any, and return home with the knowledge that, yes, indeed,

  the deadly duo of the Varroa mite and the deformed wing virus had wiped

  out the population of wild colonies of the Arnot Forest. For the first 10

  minutes, this expectation seemed correct. I found no honey bees, but I did

  encounter numerous bumble bees ( Bombus spp.), whose presence told me

  that, despite the drought, the goldenrod flowers were offering nectar and

  pollen that was attractive to bees. Then I spotted a honey bee on a shining

  goldenrod inflorescence (Fig. 2.12)! A few seconds later, she was buzzing

  furio
usly inside my bee box. A couple more minutes of searching revealed

  another honey bee on other goldenrod flowers nearby, and soon I had a

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  Bees in the Forest, Still 49

  Fig. 2.12. Worker bee collecting nectar and pollen on a goldenrod ( Solidago sp.)

  inflorescence.

  second prisoner in my bee box. Within an hour, I had spotted, captured,

  fed, and released six worker honey bees.

  My success in finding these bees showed me that there were still honey

  bees foraging in these woods. But where were they coming from? A bee

  tree in the Arnot Forest or a beekeeper’s hive outside the forest? By the

  end of the afternoon I knew the answer, for by then I had two rip- roaring

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  lines of bees leaving my syrup- filled comb, one leading north and one lead-

  ing south. Both lines pointed to locations deep in the Arnot Forest, not

  places where beekeepers would put hives.

  For the next six weeks, I devoted every available hour of every fair-

  weather day to bee hunting in the Arnot Forest. Classes at Cornell started

  in late August, and my class on animal behavior met midday on Mondays,

  Wednesdays, and Fridays, so most weekdays I could hunt for just a few

  hours in the afternoon. Also, the nights soon started to grow chilly, so

  some days the foraging bees only began appearing on the flowers late in

  the morning. In my favor, however, the drought persisted, sunny weather

  prevailed, and the bees, apparently unable to find flowers brimming with

  rich nectar, mobbed my feeder comb whenever I baited it with my anise-

  scented sugar syrup.

  All told, I hunted in the forest for 117 hours spread over 27 days, and

  during this time I started beelines from 12 clearings spread over the west-

  ern half of the forest (Fig. 2.13). As was the case back in 1978, I did not

  make a complete, forest- wide survey of the wild colonies living in the

  Arnot Forest. Nevertheless, I did find eight wild colonies! Each one had

  taken up residence in a sturdy, live tree: two sugar maples ( Acer saccharum),

  two white ash ( Fraxinus americana), one eastern hemlock ( Tsuga canadensis),

  one white pine ( Pinus strobus), one quaking aspen ( Populus tremuloides), and

  one red oak ( Quercus rubra). To have found eight trees occupied by honey

  bees delighted me, for it showed that there were about as many wild colo-

  nies living in the Arnot Forest in 2002 as there had been back in 1978,

  when I had found nine wild colonies.

  How could this be, given that Varroa had been in New York State for

  most of the previous decade? One possibility is that the honey bees in the

  Arnot Forest lived in such isolation that they had not been exposed to Var-

  roa. The fact that few of my beelines pointed out of the forest (just those

  pointing west from sites 3, 5, and 9, as shown in Fig. 2.13) showed that

  there were few, if any, managed colonies living near the Arnot Forest. It

  was possible, therefore, that the colonies living in this forest had simply

  not yet been exposed to Varroa.

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  Bees in the Forest, Still 51

  1400

  Newfield State Forest

  Newfield State Forest

  18

  1

  0

  7

  0

  1300

  0

  D

  0

  12

  B

  C

  1600

  1500

  1800

  4

  3

  1

  2

  1

  900

  1500

  ?

  1800

  1700

  1950

  A

  1600

  5

  Recknagel

  1800

  1700

  ?

  Hill

  TOMPKINS CO

  ?

  6 ?

  SCHUYLER CO 1800

  1800

  Ban

  1700

  field Cr 1 e

  9

  5

  1950

  e 0

  1700

  k 0

  1500

  E

  1

  ?

  70

  1600

  1800

  0

  Cliffside

  7

  140

  1

  0

  600

  1300

  State Forest

  1600

  10

  Irish

  Hill

  8

  1950

  1900

  1300

  1800

  McClary Road

  1700

  G

  160

  F

  0

  11

  180

  H

  0

  1800

  12

  17

  0

  1400

  00

  0

  1700

  SCHUYLER CO CHEMUNG CO

  1600

  Jackson Creek

  Cayuta

  1200

  1400

  Cree

  1

  k

  110

  200

  140

  1500

  0

  1

  0

  200

  1300

  1200

  A

  waterways

  0.5 km

  bee tree

  railroad

  0.5 mile

  trails

  true bearing

  1650

  contour

  interval

  vanishing

  roads

  buildings

  50 feet

  bearing

  Fig. 2.13. Map of the Arnot Forest showing the locations where beelines were

  started (1– 12) and where eight bee trees were discovered (A– H) during bee

  hunting in August and September 2002.

  ARE THE ARNOT FOREST COLONIES

  INFESTED WITH VARROA DESTRUCTOR?

  To see whether the wild colonies in the Arnot Forest were or were not

  infested with Varroa mites, I needed to induce several wild colonies to take

  up residence in standard, movable- frame hives, for this would enable me

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  to measure their mite loads. The easiest way to acquire wild colonies oc-

  cupying hives located in the Arnot Forest was to capture swarms in bait

  hives set out in the forest. So, in early May 2003, before the start of the

  swarm season, I set out five bait hives near the sites 1, 2, 5, 7, and 10 shown

  in Figure 2.13. Each one was an old Langstroth hive in which I had in-

  stalled eight frames of worker comb and two frames of drone comb. This

  arrangement provided the ratio of worker comb to drone comb (4:1) that

  I had found in natural nests (discussed in chapter 5). I reduced the entrance

  of each hive with a block of wood so that it was a rather small,

  16- square- centimeter (2.5- square- inch) opening, which is what the bees

  desire. Finally, I mounted each bait hive on a platform in a tree about 4

  meters (ca. 12 feet) off the ground, with its entrance facin
g south (Fig.

  2.14). My goal was to offer the bees nesting cavities whose properties

  (cavity volume, entrance area, entrance height off ground, etc.) would

  match the nest- site preferences of European honey bees and so would

  provide dream homes for honey bee swarms in the Arnot Forest.

  So that I could easily measure the mite loads of any colonies that might

  inhabit my bait hives, I equipped each one with a Varroa screen, which is

  simply a screen through which mites, but not bees, can fall. I sandwiched

  this screen between the wooden box holding the combs (the hive body)

  and the wooden bottom board (the hive floor). When I wanted to measure

  a colony’s mite load, all I had to do was insert a sticky board—a sheet of

  cardboard whose upper surface was coated with vegetable oil—beneath

  the Varroa screen and then count the mites trapped on it after 48 hours.

  This plan worked well. Three of my five bait hives were occupied dur-

  ing July 2003, and in August 2003 I started getting monthly mite- drop

  counts from these three wild colonies. The results of these assays, shown

  in Table 2.2, were crystal clear: all three colonies were infested with Varroa

  destructor. Eventually, it also became clear that all three colonies were

  surviving just fine despite the mites, for each colony’s mite population was

  rather stable during the late summer and fall of 2003, dropped markedly

  over the winter of 2003–2004, and increased only slowly and gradually

  over the summer of 2004. Also, when I inspected these colonies in late

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  Fig. 2.14. One of the bait hives installed in trees in the Arnot Forest to attract

  swarms and so acquire some wild colonies living in movable- frame hives. Instal-

  lation shown is typical: Langstroth hive mounted about 5 meters (16 feet) off the

  ground, facing south, and with an entrance opening of 16 square centimeters

  (2.5 square inches).

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  Table 2.2. Monthly assays of Varroa mite populations in wild colonies living in

  hives in the Arnot Forest. Each assay is the number of mites that dropped

  onto a sticky board over a 48- hour period at the start of the month.

  Date

  Colony 1

  Colony 2

  Colony 3

  August 2003

  30

  14

  21

  September 2003

  16

  21

  39

  October 2003

  36

  3

  22

  May 2004

  2

  2

  1

  June 2004

  3

  11

  2

 

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