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Systemic pesticides pose global threat to biodiversity and ecosystem services
un article par The Task Force on Systemic Pesticides
The conclusions of a new meta-analysis of the systemic
pesticides neonicotinoids and fipronil (neonics) confirm that
they are causing significant damage to a wide range of
beneficial invertebrate species and are a key factor in the
decline of bees. 
click on photo to enlarge
Concern about the impact of systemic pesticides on a variety
of beneficial species has been growing for the last 20 years
but the science has not been considered conclusive until now.
Undertaking a full analysis of all the available literature (800
peer reviewed reports) the Task Force on Systemic Pesticides –
a group of global, independent scientists - has found that
there is clear evidence of harm sufficient to trigger regulatory
action.
The analysis, known as the Worldwide Integrated Assessment
(WIA), to be published* in the peer reviewed Journal
Environment Science and Pollution Research, finds that
neonics pose a serious risk of harm to honeybees and other
pollinators such as butterflies and to a wide range of other
invertebrates such as earthworms and vertebrates such as
birds.
Neonics are a nerve poison and the effects of exposure range
from instant and lethal to chronic. Even long term exposure at
low (non-lethal) levels can be harmful. Chronic damage can
include: impaired sense of smell or memory; reduced
fecundity; altered feeding behaviour and reduced food intake
including reduced foraging in bees; altered tunneling
behaviour in earthworms; difficulty in flight and increased
susceptibility to disease.
One of the lead authors of the WIA, Dr Jean-Marc Bonmatin of
The National Centre for Scientific Research in France said:
“The evidence is very clear. We are witnessing a threat to the
productivity of our natural and farmed environment equivalent
to that posed by organophosphates or DDT. Far from
protecting food production the use of neonics is threatening
the very infrastructure which enables it, imperilling the
pollinators, habitat engineers and natural pest controllers at
the heart of a functioning ecosystem.”
The analysis found that the most affected groups of species
were terrestrial invertebrates such as earthworms which are
exposed at high levels via soil and plants, medium levels via
surface water and leaching from plants and low levels via air
(dusts). Both individuals and populations can be adversely
affected at even low levels and by acute (ongoing) exposure.
This makes them highly vulnerable to the levels of neonics
associated with agricultural use.
The next most affected group is insect pollinators such as
bees and butterflies which are exposed to high contamination
through air and plants and medium exposure levels through
water. Both individuals and populations can be adversely
affected by low or acute exposure making them highly
vulnerable.
Then aquatic invertebrates such as freshwater snails and
water fleas which are vulnerable to low and acute exposure
and can be affected at the individual, population and
community levels.
While vertebrate animals are generally less susceptible, bird
populations are at risk from eating crop seeds treated with
systemic insecticides, and reptile numbers have declined due
to depletion of their insect prey. Microbes were found to be
affected after high levels of or prolonged exposure. Samples
taken in water from around the world have been found to
exceed ecotoxicological limits on a regular basis.
(This article is continued in the discussionboard)
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(The following is continued from the main article listed above.)
In addition to contaminating non-target species through direct exposure (e.g. insects consuming nectar from treated plants), the chemicals are also found in varying concentrations outside intentionally treated areas. The water solubility of neonics mean that they leach and run-off easily and have been found to contaminate much wider areas leading to both chronic and acute exposure of organisms, including in riparian zones, estuarine and coastal marine systems.
They have become the most widely used group of insecticides globally, with a global market share now estimated at around 40% and sales of over US $2.63 billion in 2011. They are also commonly used in domestic treatments to prevent fleas in cats and dogs and termites in wood structures.
Chair of the Task Force, Maarten Bijleveld van Lexmond said: “The findings of the WIA are gravely worrying. We can now clearly see that neonics and fipronil pose a risk to ecosystem functioning and services which go far beyond concerns around one species and which really must warrant government and regulatory attention.”
Honey bees have been at the forefront of concern about neonics and fipronil to date and limited actions have been taken, for example by the EU Commission, but manufacturers of these neurotoxicants have refuted any claims of harm. In reviewing all the available literature rather than simply comparing one report with another, the WIA has found that field-realistic concentrations of neonics adversely affect individual navigation, learning, food collection, longevity, resistance to disease and fecundity of bees. For bumblebees, irrefutable colony-level effects have been found, with exposed colonies growing more slowly and producing significantly fewer queens. . ... continuation.
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