Neonicotinoid insecticides

Bee - Gillian DayBee - Gillian Day

The Wildlife Trusts are calling for an outright ban on the use of all neonicotinoid insecticides.

There is a growing body of evidence to show that neonicotinoids have a detrimental effect at sub-lethal doses on insect pollinators; pose a serious risk of harm to a wide range of beneficial invertebrate species in soil, vegetation, aquatic and marine habitats; have a harmful effect on a variety of vertebrate species; pose a severe risk to the wider environment and delivery of essential ecosystem services; and may adversely impact human health.

For these reasons, The Wildlife Trusts believe that the continued use of neonicotinoids in the UK represents an unacceptable risk to insect pollinator populations and ecosystem health. We urge the Government to retract its opposition to the EU ban, recognise the scale of the risks posed by the continued use of neonicotinoids and place a permanent moratorium on the use of all neonicotinoid insecticides.

You can download our position statement at the bottom of this page.
 

What are neonicotinoids?

Neonicotinoids are a relatively new group of systemic insecticides routinely used in modern farming systems to help protect crops from sap-sucking insects, such as aphids, and other insect herbivores.

In the UK, five neonicotinoids are registered for use: imidacloprid, clothianidin, acetamiprid, thiacloprid and thiamethoxam. They are used mainly for treatment of oilseed rape, cereals and potatoes.

The European Food Safety Authority’s risk assessment of three neonicotinoids (clothianidin, imidacloprid and thiametoxam) resulted in the European Commission introducing a two-year ban of their use on crops attractive to bees in December 2013.

How do they work?

Neonicotinoids are neurotoxic and act on the insect’s nervous system, resulting in paralysis and death.

Neonicotinoids are usually applied as a seed dressing or soil treatment. They are taken up in the sap as the plant grows and transported to roots, stems, leaves and flowers, so that insect herbivores such as aphids will die after consuming treated crops.

Impacts on pollinating insects

 Some neonicotinoids are at least 5,000 to 10,000 times more toxic to bees than DDT.

 

Neonicotinoids contaminate the crop’s pollen and nectar sources, so all insects feeding on nectar, including pollinators such as honey bees, bumble bees, hoverflies and butterflies, are exposed to a small dose of the toxin when the crop is in flower.

The effects of exposure to neonicotinoids range from instant and lethal, to chronic; even long term exposure at low (non-lethal) levels can be harmful. There is a growing body of evidence, using field-realistic dosages of insecticide, to show that ‘sub-lethal’ doses affect the survival of honey bees and bumble bees by interfering with foraging behaviour and foraging efficiency. 

Colony Collapse Disorder

A major factor in the global decline of bee populations is a phenomenon known as colony collapse disorder (CCD). This occurs when the majority of worker bees within a colony disappear and leave behind a queen, plenty of food and few nurse bees to care for immature bees and the queen. It is currently unclear as to what causes CCD, however, scientific research from over the last decade indicates that the increased use of neonicotinoid pesticides may be accelerating instances of CCD.

The agro-chemical companies that produce neonicotinoids claim that the major factor causing colony collapse disorder is the infestation of hives with the Varroa destructor mite. The Varroa mite is an aggressive parasite of honeybees, largely due to their ability to transmit diseases including deformed wing virus.  However, the claim that they are the main cause of bee decline is inconsistent with observations of CCD in bumblebees and Japanese honeybees. Both these species have high resistance to the Varroa mite and therefore suffer few negative effects from infestation, yet CCD has been recorded in both.
 

Wider environmental impacts

In June 2014, the Task Force on Systemic Pesticides published the largest global study into the effects and risks of systemic pesticides, including neonicotinoids.

Having studied over 1,000 peer reviewed papers, the Task Force concluded that:

• Neonicotinoids impact all species that chew a plant, sip its sap, drink its nectar, eat its pollen or fruit and these impacts cascade through an ecosystem, weakening its stability.

• The combination of persistence (over months or years) and solubility in water has led to large scale contamination of, and the potential for accumulation in, soils and sediments, ground and surface water and treated and non-treated vegetation.

• 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 treated areas. They run off into surrounding soil and aquatic habitats easily. This polluted water, along with the dust created during the drilling of treated seeds, can contaminate wild plants growing in agricultural field margins and hedgerows providing the potential for major impacts on a broad range of non-target herbivorous invertebrates living in or near farmland.

• This provides multiple routes for chronic and acute exposure of non-target species. Organisms inhabiting farmland are being chronically exposed and so are aquatic organisms living downstream of farmland, including inhabitants of riparian zones, estuarine and coastal marine systems.

• The large scale bioavailability of these insecticides in the global environment at levels that are known to cause lethal and sub-lethal effects on a wide range of terrestrial, aquatic and soil beneficial microorganisms, invertebrates and vertebrates, poses risks to ecosystem functioning and services provided by terrestrial and aquatic ecosystems including soil and freshwater functions such as litter break down and nutrient cycling, food production, biological pest control, and pollination services.

Oil seed rape - Gillian Day

Latest research

7 January 2016 – European Food Safety Authority begins review into extending ban on three neonicotinoids

EU scientists begin review of ban on pesticides linked to bee declines

The European Food Safety Authority (EFSA) has begun a review that could allow for the extension of the current EU-wide ban on three neonicotinoids: imidacloprid, clothianidin and thiamethoxam.

  • The risk evaluation should be finished by January 2017, as stated in a letter from EFSA to the EU Commission.
  • The restrictions on the use of neonicotinoids remain in place while this review is carried out.
  • Evidence from the EFSA study could be used to support an extension and tightening of an existing ban on neonics, following an EFSA ruling in 2012 that they posed an unacceptable danger to bees.
     

6 January 2016 – US Environmental Protection Agency (EPA) releases report for Risk Assessment on Imidacloprid and its impact on bees.

EPA Releases the First of Four Preliminary Risk Assessments for Insecticides Potentially Harmful to Bees

This report focuses on the most widely used neonicotinoid, imidacloprid, and confirms that it can pose significant risks to honeybee populations.

 

  • Study found that pollinators going back to the hive with concentrations of imadacloprid greater than 25 parts per billion showed decreased populations and produced less honey.
  • EPA confirms it will be conducting reviews on clothianidin, thiamethoxam and dinotefuran, which will be completed by December 2016.
  • However, it is important to note that this review has been highly criticised by many, principally because it only looked at the effect of imidacloprid on honeybees, and not native bees (4,000 species) or other insect pollinators.
     

22 April 2015 - two studies published in the journal Nature.

1. Kessler, S. C. et al. (2015) Bees prefer foods containing neonicotinoid pesticides 

Research led by Geraldine Wright, an insect neuroethologist at Newcastle University, looked into whether bees could taste neonicotinoids and therefore choose to avoid them.  Honeybees (Apis mellifera) and buff-tailed bumblebees (Bombus terrestris) were confined to boxes and given a choice between plain nectar and nectar laced with three of the most common neonicotinoids - imidacloprid (IMD), thiamethoxam (TMX) or clothianidin.

  • The bees showed no preference for the plain nectar.
  • Bees of both species preferred to eat more of the nectar laced with IMD or TMX than than the plain nectar
  • Bees cannot taste neonicotinoids and are not repelled by them
  • Treating flowering crops with IMD and TMX presents a sizeable hazard to foraging bees. 

2. Rundlöf, M. et al. (2015) Seed coating with a neonicotinoid insecticide negatively affects wild bees

This study looked at honeybees and wild bees in the field. Researchers in Sweden analysed eight fields of oilseed rape sown with seeds treated with the neonicottinoid clothianidrin, and eight fields sown with untreated seeds.

  • Wild bee density in treated fields was around half that in untreated fields.
  • Nests of solitary bees, and bumblebee-colony growth were also reduced in treated fields.
  • Honeybees, however, did not show a difference between treated and untreated fields - perhaps because they have larger colony sizes, which could sustain higher losses of foraging bees before showing overall health effects.  
  • "Honeybees are the model organism that is used in toxicity testing for pesticides,” says Dr Maj Rundlöf, lead author of the study. "If they are not representative of bees in general, it could explain why more studies have not detected negative effects."

 

8 April 2015 - European Academies Science Advisory Council report

Ecosystem services, agriculture and neonicotinoids - EASAC policy report 26

EASAC is the European Academies Science Advisory Council, a network of the national science academies of the EU Member States, Norway and Switzerland. In the wake of the Commission's 2013 regulation restricting some uses of neonicotinoids to protect bees, EASAC assembled 13 leading experts to review the science.

Their report came to four key conclusions:

1. There is an increasing body of evidence that the widespread prophylactic use of neonicotinoids has severe negative effects on non-target organisms that provide ecosystem services including pollination and natural pest control.

2. There is clear scientific evidence for sub-lethal effects of very low levels of neonicotinoids over extended periods on non-target organisms, which should be addressed in EU approval procedures.

3. Current practice of prophylactic usage of neonicotinoids is inconsistent with the basic principles of integrated pest management, as expressed in the EU's Sustainable Pesticides Directive.

4. Widespread use of neonicotinoids (as well as other pesticides) constrains the potential for restoring biodiversity in farmland.
 
 

24 March 2015 - Professor Dave Goulson re-analyses data from a 2013 study by the UK Food and Environment Research Agency (FERA)

Goulson D. (2015) Neonicotinoids impact bumblebee colony fitness in the field; a reanalysis of the UK’s Food & Environment Research Agency 2012 experiment.

  • The FERA study came to the conclusion that there was no significant link between pesticide exposure and colony performance.
  • However, attempts to improve the realism of the experiment by conducting it in the field (rather than the lab) led to problems, and neonicotinoids were recorded in control colonies that should have been neonic-free.
  • Re-analysis of the data showed that colonies of free-flying bumblebees exposed to neonicotinoids used as part of normal farming practice suffer significant impacts in terms of reduced colony growth and queen production.
  • Exposure frequently occurred even on the control farm, where no neonicotinoids were used within 1 km of the bee colonies - perhaps because  neonicotinoid residues persist and can accumulate in soil from usage in previous years, or because the bees travelled further afield than 1 km to forage.

 

18th June 2014 – Review paper published on the effects of neonicotinoids and other systemic pesticides on vertebrate wildlife

Gibbons et al. (2014) A review of the direct and indirect effects of neonicotinoids and fipronil on vertebrate wildlife

This paper focuses on two neonics, imidacloprid and clothianidin, and a third insecticide, fipronil, which itself is not a neonic but does function in the same manner. Collectively they are known as systemic pesticides.

 

  • The researchers classified the effects of the insecticides on different vertebrates using the US Environmental Protection Agency’s ecotoxicity classification system. All three insecticides showed direct toxicity to vertebrates.
  • All three insecticides exert sub-lethal effects on vertebrates, including genotoxic and cytotoxic effects, impaired immune functions, reduced growth and reduced reproductive success. These effects occurred at concentrations of the insecticides well below those associated with mortality.
  • Imidacloprid showed moderate to high toxicity to birds. 
  • Clothianidin was moderately to nearly no toxicity to rats, mice and birds and was practically non-toxic to fish. 
  • Fipronil was highly toxic to game birds and fish.
     

17th December 2014 – European Food Safety Agency (EFSA) recommends that EU Commission reduce the acceptable human exposure limits to two neonicotinoids

EFSA report - Controversial pesticides linked to human neurotoxicity

The report states that two neonicotinoids – acetamiprid and imidacloprid – may affect the developing human nervous system, and in light of this, the acceptable exposure levels of these pesticides should be lowered to prevent detrimental effects.

  • The recommendation comes as a result of recent research into the effects of neonicotinoid neurotoxicity, including a recent 2012 paper by a team of Japanese scientists on acetamiprid and imidacloprid.
  • That paper recommended further study on neonics toxicity, but found that both neonicotinoids studied had similar effects on the mammalian brains of neonatal to nicotine, causing prolonged excitation and damage to neurons.
  • The authors point out that this may disrupt brain development in humans as well as in the rats studied.
     


 Carder bee - Rachel Scopes

 

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