Research
demonstrates for the first time the knock-on effects to other species of class
of insecticides known to harm bees
The Guardian, Damian Carrington, Wednesday 9
July 2014
 |
| A barn swallow hunting over a flowering oilseed rape field, Spain. Photograph: Alamy |
New
research has identified the world’s most widely used insecticides as the key
factor in the recent reduction in numbers of farmland birds.
The finding
represents a significant escalation of the known dangers of the insecticides
and follows an assessment in June that warned that pervasive pollution by these
nerve agents was now threatening all food production.
The
neonicotinoid insecticides are believed to seriously harm bees and other
pollinating insects, and a two-year EU suspension on three of the poisons began
at the end of 2013. But the suspected knock-on effects on other species had not
been demonstrated until now.
Peer-reviewed research, published in the leading journal Nature this Wednesday, has revealed
data from the Netherlands showing that bird populations fell most sharply in
those areas where neonicotinoid pollution was highest. Starlings, tree sparrows
and swallows were among the most affected.
At least
95% of neonicotinoids applied to crops ends up in the wider environment,
killing the insects the birds rely on for food, particularly when raising
chicks.
The
researchers, led by Hans de Kroon, an ecologist at Radboud University, in the
Netherlands, examined other possible reasons for the bird declines seen during
the study period of 2003 to 2010, including intensification of farming. But
high pollution by a neonicotinoid known as imidacloprid was by far the largest
factor.
“It is very
surprising and very disturbing,” de Kroon said. Water pollution levels of just
20 nanograms of neonicotinoid per litre led to a 30% fall in bird numbers over
10 years, but some water had contamination levels 50 times higher. “That is why
it is so disturbing – there is an incredible amount of imidacloprid in the
water,” he said. “And it is not likely these effects will be restricted to
birds.”
De Kroon
added: “All the other studies [on harm caused by neonicotinoids] build up from
toxicology studies. But we approached this completely from the other end. We
started with the bird population data and tried to explain the declines. Our
study really makes the evidence complete that something is going on here. We
can’t go on like this any more. It has to stop.”
David
Goulson, a professor at the University of Sussex, who was not involved in the
new studies, said the research was convincing and ruled out likely alternative
causes of bird decline. “The simplest, most obvious, explanation is that highly
toxic substances that kill insects lead to declines in things that eat
insects.”
There was
little reason to doubt that wildlife in the UK and other countries were not
suffering similar harm, he said. “This work flags up the point that this isn’t
just about bees, it is about everything. When hundreds or thousands of species
or insect are being wiped out, it’s going to have impacts on bats, shrews,
hedgehogs, you name it. It is pretty good evidence of wholesale damage to the
environment.”
Goulson
said that, unlike the Netherlands, the UK did not monitor neonicotinoid
pollution and the EU ban would not remove the substances from the environment.
“They are still being widely used, as the moratorium only applies to three
neonicotinoids and some crops. There is still a lot of them going into the
environment. The door is far from shut.”
A spokesman
for Bayer CropScience, which makes the neonicotinoid that was examined in the
study, disputed the findings. “It provides no substantiated evidence of the
alleged indirect effects of imidacloprid on insectivorous birds. Bayer
CropScience is working with the Dutch authorities and agricultural stakeholders
to ensure the safe use of imidacloprid-containing crop protection products and
to preserve the environment.”
He added:
“Neonicotinoids have gone through an extensive risk assessment which has shown
that they are safe to the environment when used responsibly according to the
label instructions.”
But de
Kroon said new research, including his own, was showing that neonicotinoids
posed an even greater threat than had been anticipated and new regulations had
to take this into account. In 2012, MPs warned regulators appeared to be
“turning a blind eye” to the harm caused by neonicotinoids.
David
Gibbons, head of the RSPB centre for conservation science, said: “This elegant
and important study provides worrying evidence of negative impacts of
neonicotinoid insecticides on birds. Monitoring of neonicotinoid pollution in
UK soils and waterways is urgently required, as is research into the effects of
these insecticides on wildlife.”
A Defra
spokesperson said: “Pesticide use across Europe is tightly regulated to protect
the environment and public health – [pesticides] are a safe, effective and
economical means of managing crops. We continue to review evidence on
neonicotinoids.”
Also on
Wednesday, further research showing that neonicotinoids damage the natural
ability of bees to collect food was published in the journal Functional Ecology. The work used tiny tags to track bees and found those exposed to the
insecticide gathered less pollen.
“Exposure
to this neonicotinoid seems to prevent bees from being able to learn essential
skills,” said Nigel Raine, a professor at the University of Guelph, Canada. He
said the regulatory tests, which only looked for short-term, lethal effects,
were failing to prevent serious harm. “These tests should be conducted for
extended periods to detect the effects of chronic exposure.”
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