While research is underway to determine the cause of Colony Collapse Disorder
(CCD), pesticides have emerged as one of the prime suspects. Recent bans
in Europe attest to the growing concerns surrounding pesticide use and
Neonicotinoids are a relatively new class of insecticides that share a
common mode of action that affect the central nervous system of insects,
resulting in paralysis and death. They include imidacloprid, acetamiprid,
clothianidin, dinotefuran, nithiazine, thiacloprid and thiamethoxam.
According to the EPA, uncertainties have been identified since their initial
registration regarding the potential environmental fate and effects of
neonicotinoid pesticides, particularly as they relate to pollinators.
Studies conducted in the late 1990s suggest that neonicotinic residues
can accumulate in pollen and nectar of treated plants and represent a
potential risk to pollinators.
There is major concern that neonicotinic pesticides may play a role in
recent pollinator declines. Neonicotinods can also be persistent in the
environment, and when used as seed treatments, translocate to residues
in pollen and nectar of treated plants. The potential for these residues
to affect bees and other pollinators remain uncertain. Despite these uncertainties,
neonicotinoids are beginning to dominate the market place, putting pollinators
The case of the neonicotinoids
exemplifies two critical problems with current registration procedures
and risk assessment methods for pesticides: the reliance on industry-funded
science that contradicts peer-reviewed studies and the insufficiency of
current risk assessment procedures to account for sublethal effects of
- 1. Imidacloprid
Used in agriculture as foliar and seed treatments, for indoor and outdoor
insect control, home gardening and pet products, imidacloprid is the
most popular neonicotinoid, first registered in 1994 under the trade
names Merit®, Admire®, AdvantageTM. It is moderately toxic and
is linked to neurotoxic, reproductive and mutagenic effects. It has
been found to be highly toxic to bees and other beneficial insects.
It is also toxic to upland game birds, is generally persistent in soils
and can leach to groundwater.Studies show that
imidacloprid, like other chemicals in its class, produces sublethal
effects in honeybees, which include disruptions in mobility, navigation,
and feeding behavior. Decreased foraging activity, along with olfactory
learning performance and decreased hive activity have also been observed.
been scheduled for registration review, to be completed in 2016. According
to EPA, the agency does not have adequate data to understand the potential
exposure of imidacloprid to terrestrial invertebrates that may be
exposed to imidacloprid through reliance on plant flower parts for
habitat or diet. The agency is currently requesting field residue
test data for imidacloprid residues in leaves, nectar and pollen.
- 2. Clothianidin
Clothianidin is neurotoxic and is highly toxic to bees and other non-target insects. In 2008 a massive bee die-off occurred in Germany which was subsequently
associated with clothianidin. Germany moved to ban clothianidin and other
neonicotinoids pending further investigation. Clothianidin was given conditional registration in the US in 2003, without sufficient data to support its
registration. Current data gaps include a lack of field tests for honeybees. A
study, submitted in 2007 to EPA in support of this registration criteria, was
recently deemed inadequate.
An internal EPA memo, leaked to the beekeeping community from an undisclosed source at the U.S. Environmental Protection Agency (EPA) in December 2010, shines light on a key deficiency in the agency’s efforts to protect honeybees. The memo indicated that registration of clothianidin was unsound considering the study findings, and EPA was quietly re-evaluating its use, even as they planned future expansion. Beyond Pesticides and Pesticide Action Network North
America (PANNA) wrote a letter to EPA following this leaked
memo urging the agency to remove this pesticide from the market. Read EPA's
official response to our letter, which rejects immediate action on removing
this chemical which is toxic to bees. See also what the agency initially said
to the press, and our chronology of events on clothianidin in response. Take Action: Tell EPA to protect pollinators and ban
bee-killing pesticides. Submit a public comment and make your voice heard! Also, join
our petition urging Congress to step up!
- 3. Acetamiprid
Acetamiprid has population-level effects on honeybees even
though it has low acute toxicity. Certain neonicotinoids
interfere with honeybee reproduction, ability to navigate, or
temperature regulation, any of which can have an effect on long-term
survival of honeybee colonies.
- 4. Thiacloprid
Thiacloprid is targeted to control sucking and biting insects in cotton, rice,
vegetables, pome fruit, sugar beet, potatoes and ornamentals. However, low doses are highly toxic to insects like honeybees, it also causes physiological problems in fish and is considered toxic in the aquatic environment.
- 5. Thiamethoxam
Thiamathoxam is a systemic insecticide that is absorbed and transported to all parts of the plant. Once bees and pollinators eat thepollen, the compound interfere with nerve cell information exchange, paralyzing the insect. It is considered moderately toxic, but otxic to bees, and harmful to aquatic and soil organisms.
Other Pesticides Implicated
these pesticides in bee decline and CCD can be found in the Research webpage.