Honeybees in the coalmine

Independent science demonstrates repeatedly that pesticides are directly related to decline of pollinator species and colony collapse of bees. In particular, the neonicotinoid group of pesticides and the increased herbicide use are believed to have significantly contributed to the decline. Neonicotinoids are classed separately to conventional pesticides and have escaped a considerable degree of regulatory scrutiny that conventional pesticides must undergo. However, many countries are moving to more strictly control and limit neonicotinoids.

In 2017 a paper was released - Woodcock et al 2017 'Country-specific effects of neonicotinoid pesticides on honey bees and wild bees', which documented neonicotinoid use across three countries. This paper helped explain inconsistencies from previous research but what it also explained is how very, very low (environmentally relevant) levels of neonicotinoids impact honey bees health - so they do not die, the exposures were sub-lethal - but their ability to maintain healthy colonies, known as 'hive fitness,' was reduced, co-author Richard Pywell stated in Nature 'Largest-ever study of controversial pesticides finds harm to bees' that the study revealed 'significant negative effects at critical life-cycle stages'.  [1]

'Overall neonicotinoid residues were detected infrequently and rarely exceeded 1.5 ng g−1 (w/w). As such, direct mortality effects caused by exposure to high concentrations of
neonicotinoids are likely to be rare. However, our results suggest that exposure to low levels of neonicotinoids may cause reductions in hive fitness that are influenced by a number of interacting environmental factors. Such interacting environmental factors can amplify the impact of honey bee worker losses ...Note that effect sizes differ between countries.... Neonicotinoid residues are based on summed concentrations of clothianidin, thiamethoxam, and imidacloprid.... Note that our common experimental approach applied across three countries revealed varying impacts and may explain the inconsistent results of previous studies conducted in single
countries or at few sites.'

Professor Dave Goulson is an authority on bees and has published more than 260 scientific articles on the ecology and conservation of bumblebees and other insects and discussed pollinator decline in 'Bees, pesticides and the future of farming' and the recently released Bee Quest. Professor Goulson and co-author Thomas Wood released a review paper 'The environmental risks of neonicotinoid pesticides: a review of the evidence post 2013' discussed the fact that only 5% of neonicotinoid pesticides are taken up by the plant, the rest is dispersed into the environment - soils, waterways and non-crop plants, and show remarkable persistence. Neonicotinoids hang around in the environment. The paper also discussed the presence of neonicotinoids in succeeding crops (that have not been treated with a neonicotinoid), that non-flowering crops also pose a risk to bees, wild bees can be harmed, and like other papers discussed the widening exposure in the environment and the sub-lethal effects that result in pollinator decline. [2]

There are significant issues with current risk assessment and pollinator safety:

  • There is no cumulative testing for the different mixtures of fungicides/herbicides/insecticides that pollinators are commonly exposed to. 
  • 'Subtle' problems such as navigational impairment are not considered
  • Queen health is ignored
  • Cumulative low level environmentally relevant exposures are dismissed
  • Only the active ingredient is assessed - yet a seed coating or treatment will contain other ingredients that act as synergists and make the neonicotinoid more toxic to bees.
  • Neurotoxic effects may result in behaviour changes that reduce the ability for insect colonies to thrive.
  • Non-target species are threatened by secondary poisoning: Eg. Insect eating birds are vulnerable to neonicotinoid insecticides that persist in local environments.

In 2014 The Worldwide Integrated Assessment of the Impact of Systemic Pesticides on Biodiversity and Ecosystems (WIA) [3] was published. It reviewed 1,121 published peer-reviewed studies and is the single most comprehensive study of neonics ever undertaken. It is peer reviewed, and published as open access. Chief concerns relating to the class of 'plant protection products' known as neonicotinoids outlined in the WIA include:

  1. Neonicotinoids can persist for years in soils and environmental concentrations may accumulate, negatively impacting beneficial soil invertebrates and potentially leaching into surface and groundwater.
  2. Neonicotinoids are not confined to a treated seed. Dust created (from drilling of neonicotinoid treated seeds) is lethal to flying insects and has caused large-scale acute losses of honeybee colonies. Foliar spray drift can harm non-target insects. Local non-crop plants, eg. field margins, hedgerows and near contaminated waterways have been contaminated with neonicotinoids.
  3. Neonicotinoids and fipronil have been found in nectar, pollen, and exuded guttation drops (which bees drink) of treated crops and locally growing untreated wildflowers. There is evidence bees and their colonies are directly affected and harmed by these exposures.
  4. Birds and mammals that eat the treated seeds may be killed or harmed (immune system damage, reduced fecundity, lethargy) at low doses.
  5. Best practice farming utilises 'Integrated Pest Management (IPM)'. The basis of IPM is that pesticides (including neonicotinoids) are only used when necessary. Yet farmers routinely use treated seeds, which is directly against IPM protocols. A large amount of neonicotinoid use is 'prophylactic'  - habitual use of seed dressings whether there is an insect threat or not. This can lead to resistance in insect populations and may provide no real benefit, while exposing the surrounding environment to harm.

Another significant study by Tsvetkov et al 2017 'Chronic exposure to neonicotinoids reduces honey bee health near corn crops' revealed that exposure to pollinators from seed treatments on crops is much more long lived and extensive that previously thought. (Chronic = long term).  However this study demonstrated that it was pollen from non-target plants (for example wildflowers nearby pick up neonicotinoid residues from the soil) that represented the primary route of exposure. This study revealed how levels of clothianidin affected mortality, hygienic behaviour, and the ability of the hive to care for the queen. The paper indicated that fungicides also played an acutely harmful role in bee health. [4]

What is 'full formulation'?: In discussions about Confidor, industry (the pesticide producers) do not discuss or refer to the ‘formulation’. Industry very carefully only refer to the active chemical, imidacloprid. The full formulation of these products - including seed treatment neonicotinoids - are never assessed.

Mesnage et al 2014 [5] studied the toxicity of the formulations, comparing them to the single active ingredient (the component of the formulation that governments and regulators examine for toxocity). The paper 'Ethoxylated adjuvants of glyphosate-based herbicides are active principles of human cell toxicity' demonstrated that that the formulations of neonicotinoid insecticides were much more toxic than the active ingredient - and also identified that fungicides were the most toxic of the pesticides:

  • Neonicotinoid Insecticide Confidor (200gL/Imidacloprid) – 7 times more toxic than its active chemical
  • Neonicotinoid Insecticide Polysect (5g/L Acetamiprid – 21 times more toxic than the active chemical
  • Fungicide Eyetak -cereal crops - (450g/L Prochloraz) – 3 times more toxic than the active chemical (the most toxic active chemical tested).
  • Fungicide Opus - field/cereal crops, fruit trees, vegetables & grass growing areas.- (125g/L Epoxyconazole) – 12 times more toxic than the active chemical
  • Fungicide Maronee - cereal crops -  (250g/L Tebuconazole) – 1056 times more toxic than the active chemical

Who provides the scientific studies to the main assessment agencies for the neonicotinoid pesticides? 

(A) World Health Organisation :  

The full formulation of seed treatment is never assessed

Acetamiprid: assessed in 2011. Nippon Soda Co. 

Clothianidin: assessed in 2010. Sumitomo Chemical Co

Dinotefuran:  Can’t find a toxicity assessment with the WHO

Imidacloprid:   Last assessed in 2001

Nitenpyram: Can’t find a toxicity assessment with the WHO

Thiacloprid:  assessed 2006. All toxicity studies supplied by Bayer CropScience. No studies on bees.

Thiamethoxam: assessed in 2010. Syngenta


(B) US Environmental Protection Agency - example - Clothianidin:

Clothianidin was originally evaluated through a 2003 NAFTA Joint review.

The linked paper identified studies were supplied by: Sumitomo , Chemical Takeda Agro Company, Ltd./Bayer/ Gustafson Partnership. However it is difficult to trace which companies supplied particular studies. 


(C) European Commission - example Clothianidin

The 2005 review report for the active substance clothianidin identifies the corporations who supply the studies.

Who supplies the pollinator studies? 

Who supplies the risk assessment studies for soil and waterways, for birds?

Corporations supply the safety studies,the agencies are then left to deal with the multiple petitions from independent organisations claiming the pesticide causes harm. The agencies then deny the science, or demand more science from the pesticide corporations. Independent public domain studies do not get accepted.  They are ignored. 

Petitions and demands for reassessment challenge science that can't be regarded by the public and is hidden by commercial confidentiality agreements.  Existing science held by the agencies is directly paid and supplied by the same companies directly dependent on product sales.


[1] Country-specific effects of neonicotinoid pesticides on honey bees and wild bees. Woodcock et al 2016. Science  30 Jun 2017: Vol. 356, Issue 6345, pp. 1393-1395 DOI: 10.1126/science.aaa1190

[2] Wood, T.J. & Goulson, D. The environmental risks of neonicotinoid pesticides: a review of the evidence post 2013 Environ Sci Pollut Res (2017). doi:10.1007/s11356-017-9240-x

[3] Maarten Bijleveld van Lexmond & Jean-Marc Bonmatin & Dave Goulson & Dominique A. Noome 2015 Worldwide integrated assessment on systemic pesticides Global collapse of the entomofauna: exploring the role of systemic insecticides.   Environ Sci Pollut Res (2015) 22:1–4 DOI 10.1007/s11356-014-3220-1

[4] Tsvetkov et al 2017 Chronic exposure to neonicotinoids reduces honey bee health near corn crops Science 356 (6345), 1395-1397. DOI: 10.1126/science.aam7470

[5] Ethoxylated adjuvants of glyphosate-based herbicides are active principles of human cell toxicity. Mesnage R, Bernay B, Séralini GE Toxicology. 2013 Nov 16; 313(2-3):122-8. 

Ornamental plants on sale to the public are a significant source of pesticide residues with implications for the health of pollinating insects. Lentola et al 2017. 

There is no Planet B



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