Oilseed rape growers could lose one of their most powerful weapons against pest and virus attack if fresh studies into the implications for bees prove valid. Crop revenues could tumble by £170m, leaving almost half of growers wondering if the crop is still worth growing.

At the heart of the debate lies the neonicotinoid group of seed treatment insecticides, primarily represented in the UK by Syngenta’s thiamethoxam (in Cruiser) and Bayer’s clothianidin (in Modesto). New studies suggest they could be contributing to, and may even have a primary role in, bee problems around the globe.

These powerful insecticides move into all parts of the plant, to control sucking pests like cabbage stem flea beetle, turnip sawfly and turnip yellows virus-spreading aphids. With easier crop management and a 0.35t/ha average yield response, virtually all UK crops are now treated.

But new studies suggest sub-lethal side effects could be contributing to bee colony collapse disorder. In June the French government banned Cruiser OSR, sending shockwaves around a crop protection industry fearful for the future of its fastest growing class of insecticides, with sales of well over €1.5bn/year.

The implications for farmers are stark too. French producers, forced to resort to broad-spectrum foliar sprays this autumn, can expect losses of up to €230m from lower yields, says Syngenta. A global ban would take €1bn/year from farmer pockets.


  • March 2008 – Maize seed treatment error results in bee deaths in Germany
  • July 2012 – Cross industry ESTA European Seed Treatment Assurance scheme launched
  • June 2012 – Cruiser OSR banned in France
  • August 2012 – French court upholds ban
  • September 2012 – DEFRA rejects calls for a ban on neonicotinoids
  • November 2012 – UK Parliament’s Environmental Audit Committee (EAC) hears evidence
  • Early 2013 – The European Food Safety Agency will report on its in-depth review into pesticides and their possible effects on bee health


Leading UK oilseed rape business United Oilseeds shares those concerns. “Should neonicotinoid use in the UK be prevented in the future, our growers would likely experience lower yields, poorer establishment and a raise in input costs from increased spraying requirements,” a spokesman confirmed.

“As a farmer-owned co-operative, the welfare of the countryside and the environment is at the core of our ethos. But our current understanding is that there is significant debate about the robustness and validity of the French study that led to the ban in France.

“We also note that the European Commission has said it won’t be rushed into a decision to ban neonicotinoids and that this decision is supported by the majority of member states.”

A recent survey for Bayer of UK growers representing 15,000ha of OSR showed 87% felt a neonicotinoid ban here would adversely affect them, 86% felt crop establishment would suffer, 79% expected yields to fall, 90% would use more foliar sprays, 72% expected environmental implications, and 84% said they would have to spend more on pest control. Almost half (47%) said they would reconsider OSR cropping.

Campaigners opposed to neonicotinoids point out that bees provide a vital service pollinating crops, a recent Friends of the Earth study suggested they were worth an estimated £510m in the UK. Global bee pollination is valued at £128bn.

The genetic make-up of bees makes them particularly vulnerable, says the Soil Association, which believes there is enough evidence to justify an immediate ban. Green Party MP Caroline Lucas described Britain’s attitude as one of “astonishing complacency”.

Neonicotinoids used in sugar beet, wheat and barley could persist in soils, becoming available to bees when subsequent crops flower, the Pesticide Action Network suggests.

Clearly, neo-nicotinoids can harm bees – they are insecticides after all. So, growers need to heed label advice and not broadcast (or Autocast) treated seed, ensure it is well covered, avoid spills and carry a kit to clear up any that do occur, and particularly importantly, ensure any dust is retained in the product packaging, and if a pneumatic drill is used, modifications ensure any dust is vented into the seedbed and not the atmosphere.

Fine dust from maize drilling, which can contain up to 700,000 times the lethal contact dose for a bee, was linked to mass bee deaths in Germany and Italy. The newly instituted European Seed Treatment Assurance Scheme aims to prevent such acute poisonings.

Now the debate has turned to sub-lethal effects. Of course, a systemic chemical will be found in pollen and nectar at flowering, so bees do risk exposure. But how much residue bees are exposed to, whether it matters, and even more importantly, whether policymakers are listening to the scientific debate, or making politically motivated decisions, is unclear.

Not valid

French agricultural minister Stephane Le Foll banned Syngenta’s Cruiser OSR in the light of two studies earlier this year which implicated neonicotinoids in hive collapse (see panel).

But Syngenta argued that the trials were not valid, and said the ban was “completely unfounded and contrary to any scientific and rational approach”, not least because the trials force-fed bees unrealistically high doses, used an inappropriate model for bee colony decline, ignored official trial protocols, were inadequately replicated and took insufficient account of field conditions.

Cruiser OSR has been used on several million hectares of oilseed rape in Europe over the past 10 years without any damage to bees, noted Dr Phil Botham, Syngenta’s European head of product safety. He pointed instead to habitat loss, colony collapse disorder caused by the parasitic mite Varroa and the viruses it carries (including a lethal form of deformed wing virus), and other honeybee diseases such as Nosema.

Keen to address bee decline, Syngenta promotes habitat creation through Operation Pollinator, and is now funding what it says is the most in-depth independent study of bee health issues yet, considering eight factors, including neo-nicotinoids, said Luke Gibbs, the firm’s head of corporate affairs in Northern Europe.

It is also releasing its honey bee field trials data, which it says shows no effects on mortality, foraging activity, colony strength or over-wintering success during four consecutive years of exposure to thiamethoxam-treated flowering maize and oilseed rape. Pollen and nectar residue data from field trials is also being released.

Julian Little, government affairs manager for Bayer, notes that bee health showed no improvement in France even after a 10-year ban on imidacloprid seed treatment. Multi-factorial in-field studies with its successor, clothianidin, in several European countries, especially Germany for five years, would have hinted at sub-lethal effects, he says. But they never did.

In Australia, where neonicotinoid seed treatments are widely used, but Varroa and the associated viruses are absent, bees are the healthiest on the planet, he notes.

France wanted the European Commission and the European Food Safety Agency (EFSA) to impose an EU-wide ban. But EU Health and Consumer Commissioner John Dalli resisted, pending results from EFSA’s two-pronged review into the approval of neonicotinoid active ingredients under the present regulations and the regulations themselves. Results are due in early 2013.

In the meantime no other country has followed France’s lead, despite many reviewing the new studies.

DEFRA took advice from four independent bodies: the Chemicals Regulation Directorate; DEFRA’s Food and Environment Research Agency (Fera) bee unit; Defra’s Science Advisory Council; and the Advisory Committee on Pesticides.

Together with parallel work by EFSA that convinced it there were no serious implications for bee health. “There is a concern that the laboratory studies did not simulate adequately the field conditions,” chief scientist Sir Bob Watson said.

The National Bee Unit at Fera found no evidence linking neonicotinoids directly to any case of bee mortality. Existing field studies on neonicotinoids showed no significant differences between hives exposed to treated crops and hives exposed to untreated crops.

But application methods, and lethal and sub-lethal effects, will be taken into account in a new risk assessment for bumble bees and solitary bees, alongside an updated risk assessment for honey bees, due in 2013, says DEFRA. Products failing to meet the new standards would have their authorisations restricted or withdrawn.

Meanwhile, the EU Agriculture and Rural Development Committee has asked the EC to increase research and produce an action plan to conserve bees. “When the action plan is produced, we are ready to give member states a deadline to use or not use a specific pesticide – until then it is up to individual states,” said Paolo de Castro, the committee’s chairman.

Finally, Parliament’s Environmental Audit Committee is investigating the reasons why Defra has not taken more action, says chair Joan Walley. The worry is the number of sceptics on what is inherently a political committee, noted Syngenta’s Mr Gibbs.

Indeed, anti-pesticide groups, keen to have pesticide use reduced or banned outright, are loudest in calling for a neonicotinoid ban, says Mr Little. Bee and pollinator groups, by contrast, want more research, and if a smoking gun is found, tighter regulations, he says.

Whether UK growers are subjected to restrictions or a ban remain to be seen. If they are, there seems to be every likelihood that ideology, not technical issues, could be to blame.

Seed treatment studies

• Mikael Henry, INRA, Avignon, France – death rate rose when bees drank nectar laced with thiamethoxam. Tiny RFID tracking devices showed bees struggled to get to their hive, being twice as likely to die outside it. This could cause colony collapse.

• Doses administered (1.34 nano-grammes/bee) far exceeded residues measured in the field, Syngenta notes. Rather than a sub-lethal dose, it was just one-third of the LD50 dose (5ng/bee) which would kill 50% of bees.

• Dave Goulson, University of Sterling – 85% fewer queens produced by bumblebee colonies fed pollen and water containing field-realistic levels of imidacloprid. After six weeks the naturally fed hives were 10% heavier, suggesting workers brought back more food, helping support an average of 14 queens per colony. Colonies exposed to the pesticide produced just two queens. “It does suggest they’re likely to be one of the causes, and possibly a significant one,” he said.

• James Cresswell of the University of Exeter suggests neonicotinoids could depress foraging bee performance by 6-16%. “But there is no evidence that they could cause colony collapse.”

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