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See http://judson.blogs.nytimes.com/2009/01/27/guest-column-a-low-tech-treatment-for-bee-plague/?ref=opinion
Also many interesting comments on the site.
Best,
Michael
Guest Column: A Low-Tech Treatment for Bee Plague
BY AARON E. HIRSH

On a bright day last spring, I hiked at dawn into the foothills behind  
our house in Colorado. Snow still lay in the shadows beneath boulders  
and pine trees, but the morning was warm — so warm the honeybees I  
keep up there would soon awaken, emerge from their wooden boxes and  
begin searching out their first nectar of the new year.

As I climbed the final slope, I could see that two of the hilltop  
hives were already thrumming with activity: bees lifted off from the  
entry holes, catching the light and rising like sparks on a wind; and  
bees spiraled in for a landing, returning already from their first  
outings. The third hive, however, was conspicuously quiet — its  
entrance a small dark hole offering no sign of life.

Colony Collapse, I thought: The bee plague.


Bees crawl on a frame used in bee hives. (Ann Johansson for The New  
York Times)
As you’ve probably heard, honeybees are disappearing. Across the  
country, beekeepers are cracking open their hives to discover the  
remnants of a sudden and mysterious desertion: the stores of honey are  
good; the brood are tucked as usual into their cells; but all the  
adults are gone. Last winter, over a third of the honeybee hives kept  
in the United States suffered the strange fate now called Colony  
Collapse Disorder.

What’s at stake here is not just our honey, or our favorite symbol of  
cooperative society, but our food. Most of our crops require  
pollination — deposition of a bit of male pollen on the female flower  
— to set fruit and ultimately produce the parts we eat. Out of 115 of  
the world’s leading crops, 87 depend on animals — predominantly bees —  
to perform that vital act of placing pollen.

And it is important to add that, here in the United States, the  
majority of our crops are pollinated not by wild bees, or even by  
honeybees like mine, which live in one location throughout the year,  
but by a vast mobile fleet of honeybees-for-rent.

 From the almond trees of California to the blueberry bushes of Maine,  
hundreds of thousands of domestic honeybee hives travel the interstate  
highways on tractor-trailers. The trucks pull into a field or orchard  
just in time for the bloom; the hives are unloaded; and the bees are  
released. Then, when the work of pollination is done, the bees are  
loaded up, and the trucks pull out, heading for the next crop due to  
bloom.

The mobile fleets have been hit exceptionally hard by Colony Collapse  
Disorder, and if the epidemic continues, crop yields will soon  
decline. The consequences of CCD are therefore very clear. The causes,  
however, are not.

A recent survey of all the foreign DNA that could be found in honeybee  
hives discovered that a certain virus was present in 85 percent of  
hives that had fallen to CCD, but only 5 percent of hives that had  
not. That’s a strong association. But it’s not perfect, and there is  
surely more to the story.

Many of us have had the experience of contracting a cold shortly after  
an intense stretch of work. The lesson in this common ordeal — that  
the transition from health to disease is rarely so simple as exposure  
to the wrong bug — is probably as true for honeybees as it is for  
people. And CCD hit a honeybee population that was already feeling  
worn down: a large mite that attaches to bees and sucks their fluids,  
a tiny mite that inhabits the bee trachea, and a pair of fungal  
infections were all taking a toll when CCD first appeared. Not  
surprisingly, evidence of this grim company also showed up in the  
survey of foreign DNA.

But those plagues, too, could be part of a broader erosion of honeybee  
health. If you hang around beekeepers, from the hobbyists on up to the  
managers of mobile fleets, you’ll hear a variety of hypotheses about  
CCD. The mobile hives, some say, are overworked: for a species that  
evolved with an off-season and a steady home, year-round migratory  
labor must be taxing.

What’s more, each time they fly out into a new workplace, the  
itinerant honeybees encounter a variety of insecticides, herbicides  
and crops engineered to produce insecticidal proteins. And between  
jobs, they get a road-trip diet of pure corn syrup, which lacks many  
nutrients.

Some keepers say the problem isn’t just with the honeybees’ lifestyle,  
but with their genetics, as well, since they’ve been bred for traits  
that make them easier to handle, but may also render them more  
vulnerable to disease.

The list of plausible risk factors goes on. But if the cause of CCD  
truly is complex and multi-factorial, or if it simply remains obscure,  
what is there to do?

I’d like to back up a bit, because here we may need a brief history of  
bees. Honeybees first came to the New World on European ships. Once  
they’d hitched a ride across the Atlantic, however, they required no  
further assistance. They went feral, expanding swiftly — on their own  
— across the American landscape.

As the feral honeybees extended their range, they took up residence  
alongside thousands of native species of bees that were already here.  
There were the carpenter bees, which bored holes to nest in; the  
bumblebees, which formed small seasonal colonies; the orchard bees,  
which moved into the holes abandoned by others; the alkali bees, which  
burrowed in hardpan soil; and many, many others — all here before the  
honeybee.

For bees, the next important historical development was the  
transformation of landscapes. The immigrant humans set about remaking  
the continent — clearing land, building, sowing crops — and we have  
done so, at an accelerating rate, ever since. Obviously, a parking lot  
is a hard place for bees to live. Less obviously, a huge field of a  
single crop is equally unsuitable, for it lacks nesting sites, and  
yields its nectar as a sudden flood that soon recedes. Consequently,  
if a bee isn’t traveling the interstates by truck from one blooming  
field to the next, the American landscape is a tough place to make a  
living.

And yet, the wild bees — both the feral honeybees and many of the  
native species — have persisted. To this day, they are stowed away in  
our attics, hidden in holes in our wood siding and our dirt roads, and  
mostly, subsisting in the thin, semi-natural interstices of our  
transformed landscapes.

What does this mean for our current pollination crisis?

Those remnant wild bees, feral and native alike, might just be the  
seeds of a solution. And to sow those seeds and foster their growth,  
we must not till the earth, but do just the opposite: we must take  
patches of agricultural land out of production, and restore them to  
natural habitat.

At present, wild bee populations are too small, too few and too far  
between to take on the task of pollinating our crops. That, of course,  
is why fleets of domestic honeybee hives must be trucked in to do the  
job. But if the wild bees were provided with habitat of the right kind  
and in the right geographic arrangement, they could achieve  
pollination both reliably and effectively.

As the swift expansion of feral honeybees across the Americas shows,  
they are not especially picky about their habitat; most anything  
outside of parking lot or vast monoculture will do. And for native  
bees, habitat could be restored to suit the needs of whichever species  
are exceptionally good pollinators of local crops. Bumblebees, for  
instance, are the best pollinators of Maine blueberries, whereas blue  
orchard bees work well for California almonds.

The right geographic arrangement of habitat would also depend on which  
native species are desired for a certain crop. Many native species are  
willing to fly relatively far from their home habitat — a kilometer or  
so — to visit flowers; accordingly, patches of habitat for these bees  
could be placed relatively far apart.

Other species are homebodies, reluctant to fly more than a few hundred  
meters; to provide their services to an entire agricultural field,  
habitat patches would need to be closer together. Feral honeybees, for  
their part, are relatively fleet-winged, so whatever arrangement works  
for the natives will work for them, too.

Admittedly, there are costs of this rather low-tech solution to our  
pollination crisis: the opportunity cost of not cultivating those  
patches of land; the investment in restoration of habitat; the extra  
care required in applying insecticides close to established habitat.

But restoring bee habitat provides many offsetting benefits.

First, it allows us to foster the most effective pollinators for each  
crop, potentially increasing yields over levels achieved with  
pollination by domestic honeybees alone.

Second, habitat restoration is a singularly robust solution: It builds  
a diversified portfolio of potential pollinators, thus reducing our  
exposure to any one population’s collapse.

And third, a feral honeybee population distributed across a broad  
network of patches would harbor genetic diversity and inhabit a wide  
variety of environments — a wise insurance policy against problems  
with domestically bred hives.

As I arrived beside my own silent hive, I knelt and put my ear to the  
wooden box: Nothing. In a vague gesture of apology or consolation, I  
placed my hand on the box. Strangely, I received an answer: a gentle  
hum. And just then, from the dark entry hole, a bee emerged into the  
early light. Not dead, I realized. Just sleeping in.

**********

NOTES:

Thanks to D.G. Burnett, O. Judson, J. Maximon, T.H. Ricketts and V.H.  
Volny for helpful discussions.

The DNA survey of honeybee hives is reported in D.L. Cox-Foster et al.  
(2007) “A metagenomic survey of microbes in honey bee colony collapse  
disorder.” Science 318: 283-7. A good summary of current thinking on  
the causation of CCD is M.E. Watanabe (2008) “Colony collapse  
disorder: many suspects, no smoking gun.” BioScience 58: 384-8. For a  
review of the role of animal pollinators in our food supply, see A. M.  
Klein et al. (2007) “Importance of pollinators in changing landscapes  
for world crops.” Proc. R. Soc. B 274: 303-313. Two excellent papers  
on the services of native pollinators are T.H. Ricketts et al. (2008)  
“Landscape effects on crop pollination services: are there general  
patterns?” Ecology Letters 11: 499-515 and R. Winfree et al. (2007)  
“Native bees provide insurance against ongoing honey bee losses.”  
Ecology Letters 10: 1105-13.

For a guide to fostering native bees in your neighborhood, see  
“Alternative Pollinators: Native Bees.”

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