On Tuesday, the UK government released the findings of field trials commissioned to examine the effects of neonicotinoid pesticides on bee health.

The tests were conducted in response to mounting scientific evidence that the pesticides, which are amongst the most widely used in Europe, are affecting the health of insect pollinators. The EU Commission called for a partial ban of the controversial chemicals in January, prompted by advisors in the European Food Safety Authority.

UK government Agency Fera conducted its own investigation into the effects of neonicotinoids on bees the results of which, the government has assured, will inform its policy on the controversial chemicals.

In the Fera study, researchers compared the development of bumble bee colonies near fields of oilseed rape grown from seeds which had either been left untreated, been treated with neonicotinoid clothianidin or with imidacloprid, another neonicotinoid insecticide. Twenty commercial bumble bee colonies of around 16-24 worker bees were placed at each of the three sites for 6-7 weeks. At peak flowering times, samples of pollen and nectar were collected from each colony and analysed.

Fera acknowledged that there were differences between the size of the colonies measured and timing involved. The agency said it had attempted to control for these differences when analysing its results. Bees in all colonies were found to forage widely and the neonicotinoids named as harmful by EFSA were detected in all hives.

Government authors said the study revealed no clear pattern between neonicotinoid levels in pollen and nectar and colony success, which it described as "reassuring" for the government's position, but added that results are "not definitive" and recommended that further testing be conducted. Nevertheless, the agency concluded that, "were neonicotinoids in pollen and nectar from treated oilseed rape to be a major source of field mortality and morbidity to bumblebee colonies, we would have expected to find a greater contribution of insecticide residues from nearby treated crops."

University studies suggest pesticides affect bees' brain activity

On Wednesday, just one day after Fera published its results, two new bee studies reported evidence of adverse effects associated with the chemicals in question. Researchers at the University of Dundee demonstrated that neonicotinoid pesticides caused "epileptic type activity," followed by a loss of brain activity, when applied directly to bees' brains.  

In another study from Newcastle University, tests showed exposure to the chemicals impacted on bees' memory and ability to communicate, which authors said "would imply that the bees are able to forage less effectively." The researchers criticised current testing for focusing on mortality, rather than other adverse effects on bee health.

However, reacting to the findings of the two studies, government and industry commentators maintained that field trials such as FERA's are needed to provide an accurate picture of the chemicals' effects on bees in field conditions.  Defra maintains that the levels of insecticides to which bees are exposed in laboratory tests are "unrealistically high," whilst independent researchers have pointed out difficulties in establishing an adequate control group for field tests, when bees forage widely and neonicotinoid use is so widespread.

Earlier this month, Environment Secretary Owen Paterson, alongside 13 other EU ministers, succeeded in blocking the Commission's proposed restrictions on neonicotinoid use, described by the Pesticide Action Network as "a minimum step". Mr Paterson advised the Commission to stay its hand on the neonicotinoid issue until Defra had released the results of its own field tests.

However, EU health commissioner Tonio Borg has expressed a desire to press ahead with restrictions if an agreement cannot be reached between farming ministers. With over 30 studies published in the past three years alone pointing to a link between neonicotinoid use and adverse effects on bee health, Commissioner Borg said there is a need for "decisive action" to protect pollinating insects.

Even so, commenting on the outcome of Fera's research on Tuesday, Defra Chief Scientist Ian Boyd said, "Decisions on the use of neonicotinoids must be based on sound scientific evidence. The analysis of laboratory studies published by Defra today demonstrates that while we cannot rule out the possibility of neonicotinoids affecting pollinators we cannot be clear as to the extent of their impact. "

Commenting on the two UK studies, published this week in the Journal of Experimental Biology and Nature, a Defra spokesperson said, "We fully accept that the effects described in this study are real. However this study cannot be compared directly with the recently publish Fera study as it does not address whether there are significant effects in the field."

Opinion differs over necessary action

However, although Defra ministers appear content to await the results of further research, environment groups are manifestly of the opinion that "decisive action" is required to protect pollinators.

At a campaign launch at the House of Commons on Thursday (21st March), the Pesticide Action Network and Environmental Justice Foundation urged the government to suspend use of neonicotinoids until evidence clearly demonstrates that the chemicals do not pose a threat to insect pollinators. EJF director Steve Trent pointed to comments made by former Environment Lord Deben, who said that "If ever there were an issue where the precautionary principle should guide our actions, it is the use of neonicotinoid pesticides. Bees are too important to lose."

On Wednesday, Friends of the Earth Nature Campaigner Sandra Bell said of the Defra publication, "This single study doesn't counter the comprehensive review of the impact of neoniocotinoid insecticides on bee populations recently conducted by European scientists. Thorough testing should have taken place before these pesticides were licensed - it's astonishing this research is only being done now, after the chemicals have become widely used throughout Europe. 

"Defra has admitted to problems with its new study, but bee health is far too urgent to wait until more research has been completed - restrictions should be placed on these pesticides until bee safety can be assured." Friends of the Earth has accused the government of deliberately adopting delaying tactics over the neonicotinoids issue.

Soil Association head of policy Emma Hockridge also remained critical of the government's position. She said, "Defra is relying on limited trials, rather than a whole range of studies which are showing harm to bees. As we continue to see consistent evidence signalling neonicotinoids should be banned, we call on the UK Government to vote to ban a number of neonicotinoid pesticides as is currently being discussed in the EU." She said the weight of scientific evidence on neonicotinoids still "highlights the need to get off the chemical treadmill and focus on alternative ways of controlling insect pests, for example by using agroecological approaches such as organic farming."

At EJF and PAN UK's event in London last week, Keith Tyrell claimed that countries which have acted to restrict neonicotinoid use, including France, Germany and Italy, suffer fewer bee deaths and have more colonies that survive over winter. He also warned that "bees are a commercial insect, involved in the production of honey," and as such the adverse effects on honey bees has been well documented, whereas wild bees and other pollinators, including moths and bats, are also suffering population declines which have been much less popularised.