July 29, 1999
Vol . 15, No. 8
July 29, 1999 Vol . 15, No. 8
In North America, honey bees have suffered an onslaught
of new diseases and other problems in the last decade.
By Stephen Pernal
I sit in a small room, an eerie
red glow reflecting off my face. My gaze is focused on a tiny
oval-shaped mite, a few millimetres in breadth, crawling through
a y-shaped glass tube, under a red light to avoid normal light
cues. Along this transparent roadway the mite is forced to choose
between two paths, one leading to an odour source derived from
bees and one that is odour-free. This mite and several of its
successors choose to do nothing at all. After many long and puzzling
days of staring at these minuscule parasites I often ask myself,
"Why am I doing this?"
It's because bees need a helping hand to survive into the new
millennium. Honey bees and scores of lesser known but equally
important native pollinators are under siege. Without intervention,
pollinator numbers will continue their steady decline with devastating
consequences. Eighty per cent of all plant species consumed as
food are dependent on pollination by animals, almost all of which
are insects -- predominantly bees. Consider the fact that one
of every three of your mouthfuls is the direct result of our invertebrate
neighbours, and our existence is closely intertwined with the
health and abundance of these pollinating insects.
Not only are the ecological consequences of pollinator decline
devastating, but the economic impact is staggering. Beekeeping
provides employment for 11,000 Canadians who maintain between
500-600 thousand colonies. Canada is the fifth leading honey producer
in the world with annual production of over 42,000 tonnes. Gross
annual income from the sale of honey by producers exceeds $75
million, with several million more being earned by those providing
specialized pollination services, the sale of bees or other bee
products such as wax and pollen.
The most telling statistics are the direct value added to crops
by pollination, estimated at $500 million, and of the indirect
value of pollination in the production of forages such as alfalfa,
estimated at $800 million.
Why are bees under siege? The reasons are numerous. In North America,
honey bees have suffered an onslaught of new diseases, parasites
and other problems in the last decade. For example, some strains
of honey bee bacterial diseases no longer respond to treatment
because of resistance to antibiotics. Previously unknown viral
diseases are also being identified from some stricken colonies.
Since the mid 1980s, honey bees also have suffered from the microscopic
tracheal mite that feeds and reproduces in the breathing tubes
(trachea) of bees. The detection of this pest is labourious, requiring
that bees are sampled from colonies and carefully dissected to
confirm the presence of the parasite. The biggest world-wide threat
to the health of honey bees is a second parasitic mite, varroa
jacobsoni, that is found on the exterior of adult and larval bees.
It has caused devastating losses in the beekeeping industry, and
changed beekeeping practices fundamentally. Without intensive
sampling and treatment, colonies die within two years. Many hobbyists
no longer keep bees, and commercial producers are faced with increased
costs of treating bees for mites and increased time spent sampling
and managing colonies. The combination of both mite species left
untreated leads to rapid and certain colony death; honey bee colonies
surviving in the wild are now uncommon.
In Canada we have been fortunate to observe many of these problems
approaching from afar, as most honey bee maladies have invaded
the U.S. before entering Canada. As a result of varroa mite infestations
in the U.S., the international border was closed to the movement
of bees from the continental U.S. into Canada in 1987. This barrier
has slowed, but not prevented the movement of honey bee problems
into Canada, and has provided valuable time to derive solutions
before we have been faced with similar problems.
Daunting are the possible introductions of new plagues, such as
Africanized (killer) bees from the southwestern U.S. or the small
hive beetle, a deadly pest native to South Africa, recently found
in Florida. However, the next immediate problem of concern to
Canada appears to be the advent of varroa mites resistant to the
only highly effective pesticide registered for use against them,
marketed under the trade name ApistanÆ. Because of overreliance
on this product, pesticide resistance has become widespread in
the U.S. and other areas of the world, painting a bleak future
for control. It is because of this impending crisis that I conduct
studies on these eight-legged creatures, to discover what naturally
occurring compounds produced by honey bees attract the parasite.
If found, such attractants could provide the basis for developing
a non-pesticidal trapping system used against this mite, giving
us another alternative for control.
Bleak too has been the picture for other bee pollinators. Hundreds
of bee species are native to different regions of North America,
and have evolved to pollinate specific groups of plants. Although
fundamental to our understanding of many ecosystems, our basic
knowledge of the interactions between native pollinators and their
host plants is lacking.
Even for plants that are endangered, the identity of their natural
pollinators is poorly understood. Without knowledge and preservation
of native pollinators, the continued existence of many native
plants is in peril. Our population growth has led to the destruction
or fragmentation of natural habitats at an unprecedented rate
in place of sprawling urbanization or the perpetuation of agricultural
monocultures with low natural species diversity. These effects,
coupled with increasing pesticide use, are leading to the extirpation
of wild pollinators and their host plants.
A battle for the survival of honey bees and native pollinators
is being fought by dwindling ranks of scientists. Our federal
government employs only one research scientist devoted to studying
bee parasites, predators and diseases. Only a handful of other
researchers in Canadian universities work in related areas, assuming
they can procure research support for such programs. Although
trickles of financial support are available from other sources,
such as agricultural producer groups, it is difficult to fight
a war, or retain scientists willing to do so, if funding remains
virtually non-existent.
Our future is interdependent with that of our pollinators. We
require pollination to produce much of our food, but we have been
slow to realize that our own global colonization has caused catastrophic
introductions of organisms that are threats to the very organisms
that we are dependent on, and our human-induced reductions in
ecological diversity have accelerated their demise. Human endeavours
must enable a mutual sustainability with our pollinators.
Vancouver is the host city of a major international conference,
Apimondia '99: Beekeeping in the New Millennium, from Sept. 12
- 17. This event will bring together thousands of research scientists,
beekeepers and those interested in pollination biology and management
from around the world to engage in a meaningful dialogue to solve
such global problems.
Stephen Pernal is a post-doctoral fellow in the department
of biological sciences.
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