 |
| No bees here! |
Bees are dying and blogs are buzzing. A
phenomenon called ‘colony collapse disorder’(CCD) has been decimating bee
populations in North America and Europe. Bloggers are eager to put the blame
pesticides, herbicides, GMO crops and mono-cultures, but what’s really going
on? What’s this mysterious bee disease, what should we do to prevent it and
should we be really worried? Will our crops fail and nations starve when the
bees die out? Time to review the different facts and factors involved and see
if we can make some sense out of all the buzzing.
Bees:
who are they and why should we care?
First of all: not every bee is a honey bee but,
in the context of CCD, honey bees are all we care about. It’s the honey bees
that are dying. Solitary bees, carpenter bees, bumblebees and what not are not
under threat. There are in fact almost 20.000 known species of bees .
Yet, honey bees are important pollinators. By buzzing around and hopping from
flower to flower they pollinate the flowers and this is essential for some
plant species to bear fruit. Without pollination, we’d have no apples, no pears, no grapes (and no wine), no
kiwi’s and no cacao. The list goes on .
Are honey bees the only pollinating species? Not at all. We won’t see the
instant demise of all of our crops once the bees are gone. Honey bees are an
important pollinating species, but far from the only species. Other insects
pollinate too, such as bumblebees, hoover flies, midgets and even mosquitoes.
In addition, animals such as humming birds and fruit bats pollinate many crops
in regions where they’re abundant. Farmers tend to utilize honey bees to
pollinate their crops, since it’s simple enough to put up a couple of hives in
your orchard and their honey is a nice bonus, but they’re hardly essential. As
far as I could find, only a few fruit crops appear to depend on pollination by
honey bees alone, such as lemon and lime.
Still, honey bees do put in a lot of effort in the pollination of many of our
crops and crop-yields may very well be severely reduced without honey bees
around. However, it’s a gross overstatement that our world would perish and our
civilization collapse without the bees. Such overstatements sell movies, but
don’t really help us much otherwise.
Colony
collapse disorder: what’s that then?
The sudden disappearance of all the worker
bees from a hive is what causes a bee colony to collapse. No worker bees, no
food, no hive. This is not a new phenomenon, though the name CCD was only coined
in 2006. Entire bee colonies have disappeared since ancient times and this
phenomenon has been labelled as “disappearing disease” or “spring dwindling”
(Oldroyd, 2007).
However, the rate of honey bee colony loss reported in particular since the
2006-2007 season, is quite unusual. What really happens in CCD is unclear. The
bees don’t die at the hive, as such, they simply disappear. They fly out and never return
to their hives. Do they get disoriented and lose their way? They fly out and
die elsewhere? Nobody really knows. A number of causes have been proposed for
this phenomenon, primarily infectious diseases and chemical contamination of
the bees’ environment with pesticides and/or herbicides.
Infectious
diseases
Bees, like any other living thing, are
susceptible to a number of pathogens including mites, fungi and viruses. The
most prolific bee-killer is the mite Varroadestructor. This mite has
been spreading throug the world since the 1960s and has, in fact, been
responsible for decimating bee colonies, including domestic honey bees and wild
bees. However, chemicals have been developed that kill the mites, so called ‘miticides’
and, although the mite still infects virtually every colony, the infection is
under control and rarely results in colony destruction loss (Oldroyd, 2007).
In addition, it seems that the mites
have become less virulent while feral bee populations have mostly become
resistant. Another likely candidate for an infectious disease contributing to,
if not causing, CCD is a combination of a fungal and a viral disease.
Invertebrate iridescent virus (IIV6) and the fungus Nosema caranae have been linked to CCD. However, the study
identifying the IIV6 has later been called into question.
Another pathogen associated with CCD is the parasitic phorid fly.
This fly lies its eggs in life bees and when the eggs hatch the larvae eat the
bee alive. Before the bee succumbs, the larvae control the bee turning the bee
into a ‘zombee’. Such a scenario might explain why the bees of CCD colonies go
missing since infected bees won’t return to the hive to die. However, further
investigation into the role of the phorid fly is still pending and if you think you see a zombee you can help by catching it and reporting your find on the Zombee Watch site. Altogether,
although CCD appears to be linked to an infectious disease, no clarity exists
yet about the pathogen that may cause it.
Pesticides,
herbicides and GMO crops
First, there’s absolutely no evidence that
genetically modified crops are associated with CCD. To the contrary, in areas
where high amounts of GMO crops are present, such as in Illinois, no cases ofCCD have been reported.
The alarmist blogs have been blaming the herbicide Round-up, glyphosate, for
the death of bees,
but again, there’s no evidence for such claims. In fact, the latest research
shows no effect whatsoever of glyphosate on bee health.
The only substances that seem to affect bees negatively are the neonicotinoids
used as pesticides. These compounds were designed as relatively safe
insecticides to control pest-species that damage our crops.
Initial studies showed little to no effect on foraging honey bees, that might
ingest the compound through contaminated pollen.
However, a concurrent study indicates that ingestion of the compound might
render bees more susceptible to viral diseases.
Thus, the neonicotinoids are still suspect and will remain so, pending further
investigation. The E.U. has therefore banned the use of these substances for
the time being.
Conclusions
We still don’t know for certain what’s
causing CCD. A combination of factors seems likely. Over-all, the phenomenon
appears to be pathogen-related and the parasitic phorid fly seems a likely
cause. A loss of plant diversity may also be a contributing factor, as may
certain chemicals in the environment that render the bees more susceptible to
infection. However, bee populations are already seem to be recovering, bees are
not exactly on the brink of extinction. I don’t think there’s a reason to panic,
but it never hurts to be cautious.
