I do not know if
this is the smoking gun but it may be.
The surprise here is that a specific plant virus is able to transition
into the mites and then into the bees with a pretty clear outcome. Of course the hives are generally heavily
stressed and this is also inflicting serious damage.
The principles
of sound husbandry have become much clearer and the industry is on the way to
transitioning into them, mostly because the so called modern practice is
killing the industry. Thus we can expected stable hives associated with natural
fields were the plant life is optimized.
I am offended by
the present deterioration of the pollination populations, but also have
complete faith in their capacity for recovery as we cycle away from our massive
experiments in pesticides. We are not
dealing with island bound populations of birds and the onslaught of rats.
First We Fed Bees
High-Fructose Corn Syrup, Now We've Given Them a Killer Virus?
|
Wed Feb. 5,
the classic
board game Clue,
murder mysteries have clear solutions: say, Col. Mustard with the candlestick
in the dining room. In the stark recent declines of honeybees and other
pollinators, however, the situation is murkier.
We've
put bees through a lot. They have to deal with nasty parasite, the varroa mite, which
didn't make its way to the United States until the late 1980s. They also have
to deal with pesticides specifically designed to target those mites (called,
yes, miticides). Over the winter, bees in commercial hives often live not
on their own honey, as they have evolved to do, but rather a cheap substitute:
high-fructose corn syrup.
And finally, they are confronted with a range of pathogens.
Over
the past month, the dossiers on two of those suspects got a little thicker. In
the January issue of the peer-reviewed journal Ecotoxicology, UK researchers delivered yet more evidence that a
widely used pesticide class called neonicotinoids might play a decisive role in declining
bee health.
They fed one set of bumblebees pollen and sugar water containing very low
levels a neonic called imidacloprid. The team let the dosed bees forage in a
field and compared their pollen-gathering performance to those of an un-dosed
control group.
The
results: The imidacloprid-exposed bees were much worse at gathering pollen.
They brought back pollen on 40 percent of their trips, vs. 63 percent for
the control group. And when the dosed bees did manage to snag pollen, they
brought back on average 31 percent less than their un-dosed peers.
Exactly
why exposure to the neonics—which act as a neurotoxin to bees and other
insects—hindered their ability to bring home the bacon "remains unclear,"
the researchers state. But less food means less-healthy hives, making them more
vulnerable to the range of other problems plaguing these critical pollinators.
The bees had caught a
virus previously thought to affect only plants.
Another
recent study adds new weight to the pathogen theory of bee decline. In this one, US and Chinese researchers looked
at six healthy and four struggling honeybee colonies and screened them for the
presence of various viruses. They found, surprisingly, that bees in the
unhealthy colonies tended to be infected at high rates with tobacco-ringspot
virus, a pathogen previously known only to infect plants, not animals. The
healthy hives were all free of the virus. Tobacco-ringspot virus gets into the
hives via pollen, the researchers state; and once there, it "invades and
replicates in different body parts" of the bees. Disturbingly, they found
that the virus also replicates in varroa mites, an established bee pest, and that the infected mites could
help spread the virus.
How
did a plant pathogen end up flourishing in bees and their parasites?
Tobacco-ringspot virus is a fast-mutating beast, it turns out, and it has
evolved the ability to infect insects. (The authors note 5 percent of all known
plant viruses move about via pollen, representing the potential for more
"host-jumping" pathogens that can affect insects like honeybees.)
At
any rate, the six healthy, virus-free hives survived the winter during the
study, while the four unhealthy, virus-riddled ones all collapsed before
February.
And
of course, neonics and other agrichemicals, including fungicides, have been shown to make bees more
susceptible to being laid low by other viral pathogens found in the environment. Human beings can't stop plant
viruses from mutating in ways that make them harmful to bees. But we can stop
farmers from using chemicals known to hinder bees' resilience in the face of
such threats—as Europe did last year, with its two-year moratorium on neonics, instituted to buy scientists more time to study
the issue ahead of a possible permanent ban. That seems as wise as training a
wary eye on Col. Mustard when he grips that candlestick at dinner.
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