Around this time last year in Germany a catastrophic
error was being made during the treating of maize seed with the
insecticide clothianidin.
A failure to use the glue that sticks the pesticide to the seed
led to the chemical getting into the air during drilling, and
resulted in
millions of honey bees dying in the Baden-Wurttemberg region
that runs alongside the Rhine in Germany (see panel).
The approval for some of the Poncho products has since been
reinstated in the country. In the UK existing approvals in sugar
beet and oilseed rape were not affected, and the product, albeit at
a lower rate than in Germany, is also now approved in maize for the
first time this spring.
But it wasn't the first time neonicotinoids have been implicated
in bee problems. France banned the use of another neonicotinoid,
imidacloprid (Gaucho), in sunflowers in 1999 after heavy bee losses
in 1997. Beekeepers in other countries, particularly the USA, have
also sent accusatory glances towards pesticides.
With that background it is probably not surprising that last
month the Co-operative Group became the first UK retailer to
temporarily, at least, prohibit the use of eight insecticides for
use on its own brand fresh produce, as part of its "radical"
10-point plan to reverse the decline in British honeybees.
Launching
"
Plan Bee", the Co-op said the chemicals had been implicated in
honeybee colony collapse and as a precautionary measure it would
engage with suppliers to eliminate their usage where possible, and
until such time as they were shown to be safe.
One third of the average diet relies on honeybees, Paul
Monaghan, head of social goals at the Co-op, says. "But nature's
number one pollinating machine appears to be breaking down and no
one for sure knows why. The government has accepted there is a
problem, however, we are still not seeing any real recognition that
pesticides could be a contributory factor."
Not surprisingly Julian Little,
Bayer CropScience's communications and government affairs
spokesman, has a different view - one where pesticides are not a
main contributory factor.
"There are other problems," he says. "The primary one is
verroa
mite, a parasitic mite, which left unchecked means you can lose
a colony quickly.
"Unfortunately it has grown resistant to the major treatments,
such as, our Bayvarol strips, which are impregnated with
insecticide that control mites but is harmless to the bees.
"Resistance is now endemic, which means there is no standard way
of controlling verroa."
Colonies weakened by verroa are also more susceptible to the
other main problems for bees, bacterial, viral and fungal diseases,
according to Dr Little. "They are also becoming endemic, partly
because of climate change."
Together those issues make up 90-95% of the reasons why bee
numbers have declined, he claims.
Pesticides are less of an issue, he reckons. "Of course, if you
apply clothianidin directly onto a bee it is not going to be very
happy. That's why you cannot spray clothianidin in the UK - it is
only available as a seed treatment.
"But PSD has said
when it is applied appropriately there is no hazard to non-target
organisms."
Simon Press, the Co-op's senior technical manager, agrees there
are other factors contributing to colonies collapsing, but says the
German incident focused attention on the neonicotinoid
insecticides.
In addition, some French research suggested imidacloprid
affected communication between bees at sub-clinical levels.
"So we decided partly due to the issues in Germany and because
of this research we wanted to take the extra step."
The Co-op's policy doesn't mean growers cannot use the products,
he points out. "It is a prohibition, not a ban. We don't want
growers to use them, but if growers do find they have to use them
because there are no other chemicals around or for proven
resistance management strategies, then they have to ask for a
derogation."
The restrictions also only apply to crops that bees pollinate or
forage upon, he stresses. For most mainstream arable growers it
would only affect those growing vining peas or potatoes for the
retailer.
Dr Little points out the decision to blanket prohibit
neonicotinoids is too wide-reaching. "For example, it includes
thiacloprid (Biscaya), which is incredibly safe to bees. It even
has a label approval for spraying when bees are foraging and
flowers are in full view.
"We wouldn't necessarily encourage that - as a good agricultural
practice is it not particularly clever - but the Co-op decision not
to allow its use, the chances are the farmer will have to use a
more bee-toxic product instead.
"It is unfortunate the Co-op made such a sweeping decision."
As part of Plan Bee the Co-op has allocated £150,000 for bee
research - part of it going towards researching whether
neonicotinoids do affect bee communication, Mr Press says.
Favourable research could allow the restrictions to be lifted, he
stresses.
Dr Little suggests the research could have been targeted better.
"Any money going into bee health is a good thing. Good bee health
is important for crops - we're dependent on bees for breeding new
oilseed rape varieties, for example."
"But it is disappointing that the Co-op hasn't targeted its
research at the bigger problems."
According to Dr Little the Co-op has stipulated the research
must be in three areas: Changing agricultural practises, increasing
the genetic diversity in bee populations and the impact of
pesticides. "At best it is targeting some of the smaller problems.
I just feel it is somewhat misdirected."
DEFRA has also pledged to spend over £4 in trying to improve bee
health in the next five years.
What happened in Germany?
The use of treated seed is obligatory over an area of 4000ha in
the region affected to prevent western corn rootworm from spreading
further.
Maize sowing last spring had largely been finished when the
reports of bee losses started coming in. According to Manfred
Herderer, the president of the German Professional Beekeepers'
Association, around 50-60% of bees died on average, with some
beekeepers losing all their hives.
Not surprisingly the German pesticides approval authority, BVL,
reacted swiftly by suspending registration for eight insecticidal
seed treatments used in oilseed rape and maize in mid-May.
Investigations found that along with the abrasion of incorrectly
treated seed during sowing, the problem was exacerbated by the use
of certain types of pneumatic drills and strong winds. The high
doses of clothianidin required to control western corn rootworm
also contributed, according to Dr Little.
Despite the problem being human error, so far, the German
authorities have not re-instated the approval for Poncho Pro in
Germany. "We hope it will come in time," Bayer's Nigel Adam
says.
But Bayer does have approval for a lower dose Poncho for use in
the UK on maize. "Its dose is half that of Poncho Pro because we
don't have western corn rootworm."
Even so, strict stewardship guidelines have been put in place
including a stipulation that the correct sticker must be used,
which is supplied to the seed treater with the active.
Bayer is also providing help modifying older maize drills to
prevent seed dust being from vented into the air. "The drills work
on a suction/vacuum system to place the seeds accurately, which
means air needs to be extracted and then released through an
exhaust system.
"In all but very new drills it is vented upwards, so we are
instructing growers and contractors how to modify the drill cheaply
to vent the air downwards instead."
Combining that measure with using the right sticker should
reduce dust, in theory, by 100-fold, he says.
German research
A four-year study conducted by German Bee Research Institutes
has found that there is significant correlation between winter bee
losses and varroa and virus infestations in the autumn.
The study, done in collaboration with bee farmer and keeper
organisations and major agchem firms, conducted comprehensive tests
of over-wintering losses with around 120 beekeepers and 1200 bee
colonies.
Among the factors recorded were apiary site and management
details such as colony formation, migration and varroa control,
colony size in autumn and spring, honey yield, pest and disease
infestation and pesticide residues in bee bread - the main source
of food for honeybees and their larvae and made from pollen and
nectar collected by worker bees.
Winter bee losses in the study were between 8-16% on average,
with marked regional variations - well below losses shown by
surveys.
The key finding was that the larger the verroa infestation in
the autumn the more likely the hive was to suffer losses.
Trace levels of around 55 different active substances, mostly
fungicides, acaricides used to control varroa and herbicides, were
found in the 215 analysed bee breads.
But clothianidin was not detected, and imidacloprid only found
in one sample close to the level of detection. The study concluded
that the data did not indicate any direct harmful effects on bees
was to be expected.
It did, however, recognise a suitable method was needed to
assess sub-lethal and long-term effects from bees feeding on bee
bread with pesticide residues.