Honeybees, image by ShutterstockThe Centre for Ecology & Hydrology (CEH) is undertaking research to quantify the impact on honeybees of two commercial neonicotinoids seed treatments in commercially grown crops of oilseed rape (‘Clothianidin’ Bayer CropScience and ‘Thiamethoxam’ Syngenta).

A pan-European, field experiment has been designed and will be delivered during 2014-2015. The results will provide policy makers and regulators with independent, high quality scientific evidence on the effects of neonicotinoids (NNI) on honeybees and help to inform their decisions.

CEH researchers have designed, and are overseeing, the delivery of this trial. The work aligns with NERC and CEH’s scientific aim of monitoring the impacts of human actions on the environment.

Impacts on wild pollinators are also being assessed using the trial infrastructure.



Neonicotinoid seed dressings have been used extensively across Europe and elsewhere since the early 2000s to protect oilseed rape and other important crops against pests1. They have recently been implicated in the decline of wild bees and harm to domesticated honeybees, and this led to a moratorium on some uses in the EU while more data are generated. However, evidence for NNI impacts on bees is inconclusive and so the ban remains controversial2. Laboratory studies suggest some toxicity to bees3, but these experiments are highly artificial and their relevance to the real world is unclear. Field trials provide a more realistic test of impacts on bees of NNI use by farmers, but some of these studies have proven inconclusive4, 5, and have been criticised for a range of reasons including contamination of the no-NNI control, low replication and small plot sizes6.

This research is co-funded by Bayer CropScience AG and Syngenta Crop Protection, but controls are in place to ensure the experimental design and the reporting of its research (whatever the outcome) is independent.


NERC's Centre for Ecology & Hydrology has designed and is implementing a large-scale field experiment to quantify the impact on honeybees of two commercial neonicotinoids seed treatments in commercially grown crops of oilseed rape (‘Clothianidin’ Bayer CropScience and ‘Thiamethoxam’ Syngenta).

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Lead scientist, Professor Richard Pywell explains more about the field trial in our video


Frequently Asked Questions

Why are the field studies needed? Seeing as the ban has been maintained, is there a need for this experiment?

  • The evidence base relating to the effects of neonicotinoid use on pollinators is considered to be deficient by many scientists:
    • previous field studies have been criticised for being poorly replicated & small scale;
    • laboratory studies have been questioned for not representing real world exposure
  • The European Food Standards Agency (EFSA) recent (2013) guidelines on the risk assessment of plant protection products on bees make clear the importance of field exposure studies and outline how these should be designed7.
  • EFSA have stated they will review new and existing evidence regarding neonicotinoid effects on pollinations in December 2015.

What steps have been taken to ensure the project is independent and free of bias?

  • All aspects of the project (design, monitoring, analysis, data etc) are being scrutinised by an independent Scientific Advisory Committee. This committee was chaired by Prof Charles Godfray, FRS (Oxford University) until 31 Dec 2014 and is now chaired by Prof Bill Sutherland (Cambridge University). Prof Godfray FRS was appointed as chair of Defra’s Science Advisory Committee from 1 January 2015 and thus resigned as the advisory group chair. 
  • CEH has had complete freedom to design the experiment within the constraints of the budget provided.
  • We will submit all findings of the study (regardless of outcome) for peer-reviewed publication.
  • Data relating to the trial will be made publically available.

What steps have been taken to ensure the trials are scientifically robust?

  • Following the EFSA guidelines, qualified CEH statisticians have undertaken a rigorous statistical power analysis to ensure that the experiment has a sufficient number of replicates to have confidence in the detection of ‘no neonicotinoid effect’.
  • The experiment will be conducted in three European countries (United Kingdom, Germany, Hungary) where a large amount of oilseed rape, previously treated with neonicotinoid, has been grown.
  • The study will be conducted on large contiguous fields of oilseed rape (ca. 50ha) managed by commercial farmers using typical agronomic practice. Treated and untreated fields will be separated by at least 4km following EFSA guidelines.
  • The size of the treated patch is a compromise between the area of crop likely to be approved under experimental licence and the foraging distance of honeybees to ensure a realistic field exposure to the pesticide, ie there will be fewer opportunities to forage on neighbouring habitats and possibly untreated oilseed rape. This will ensure, as far as possible, a realistic, ‘real world’ exposure of bees to neonicotoinoid.
  • The pan-European ban on neonicotoinoid seed dressings will help ensure the no-treatment controls are not contaminated (a criticism of previous field studies).
  • Measurements of effects on honeybees will follow the guidelines provided by EFSA, including colony grow rate, worker mortality, overwinter survival, and infestations of pests and disease. We will also sample extensively for residues of neonicotinoid in the soil and plant tissue; nectar, pollen, and stored hive products (wax and honey).

Where are the trials taking place?

  • The experimental trial plots are located in the United Kingdom, Germany and Hungary and will be harvested in 2015. This gives a good bio-geographic spread across Europe in countries where intensive oilseed rape cultivation is a typical and increasing practice.

Related Documents

1. Jeschke P., Nauen R., Schindler M. & Elbert A. (2010). Overview of the status and global strategy for neonicotinoids. Journal of Agricultural and Food Chemistry, 59, 2897-2908.
2. Cressey D. (2013). Europe debates risk to bees. Nature, 496, 408.
3. Whitehorn P.R., O'Connor S., Wackers F.L. & Goulson D. (2012). Neonicotinoid pesticide reduces bumble bee colony growth and queen production. Science, 336, 351-352.
4. FERA (2013). Effects of neonicotinoid seed treatments on bumble bee colonies under field conditions. The Food and Environment Research Agency, Sand Hutton, York YO41 1LZ.
5. Pilling E., Campbell P., Coulson M., Ruddle N. & Tornier I. (2013). A four-year field program investigating long-term effects of repeated exposure of honey bee colonies to flowering crops treated with thiamethoxam. PLoS ONE, 8
6. Environmental Audit Committee Oral evidence session: National Pollinator Strategy, Wednesday 18 June 2014. Second Report of Session.
7. EFSA (2013). Guidance on the risk assessment of plant protection products on bees (Apis mellifera, Bombus spp. and solitary bees). EFSA Journal 11:3295, 266.

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