Supermarket retailer the Co-operative has temporarily banned the use of eight pesticides in its products to help reverse declines in Britain’s bee population. It has asked its top-tier suppliers to stop using the chemicals - all neonicotinoids - immediately.
The move follows concern over rising bee deaths across the globe, including the UK. In some regions a third or more of hives have disappeared. Colony collapse disorder (CCD), where a sudden loss of adult worker bees results in entire colonies dying, has been linked to many of the losses.
No cases of CCD have been detected in the UK but the bee mortality rate is still significant. The Environment Department (DEFRA) recorded a 12% colony loss in hives inspected in England and Wales last year, the highest level in at least the past ten years. Some experts think losses are much higher, particularly south of London and in South Wales.
In what is the UK’s largest such private sector initiative, the Co-operative has set aside £150,000 for research into the decline of bee populations. It wants to look at the impact of pesticides, farming practices, and the diminishing bee gene pool. A three-year project to identify the best mix of wildflowers to sow in field margins and set-aside land to attract and support honey bees will also begin this year.
The Co-operative’s decision to ban neonicotinoids is controversial. The chemicals, introduced in the 1990s, are popular with growers. In 2007 they generated about €800 million in profits for Bayer, of which €556 million came from Imidacloprid sales.
The chemicals attack insects’ nervous systems causing paralysis and death. In the UK, they have been approved for use on a range of crops such as hops, barley, sugar beet, oilseed rape and ornamental plants.
Concern has been mounting over neonicotinoids’ potential impact on pollinator bees. Exposure to high levels can be toxic to bees but the picture is less clear for long-term exposure to lower levels. Residues have been shown to accumulate in the pollen and nectar of treated plants. Lower levels of exposure have some effect on bee behaviour and studies suggest it makes them more susceptible to viruses and Nosema, a disease linked to bee deaths in Spain.
The emerging scientific consensus is that no single factor is to blame for the high mortality. "We do know that the bee immune system is not functioning as it should," said Dewey Caron, professor of entomology and wildlife ecology at the University of Delaware and part of a task force investigating CCD in US honey bees.
He said US sampling has revealed dying bees have higher levels of Nosema and at least four other pathogens. Poor beekeeping and bad weather have also been implicated.
"Any one of these might kill them but they are all present in the same colonies," he said. "The bees are dying from poor health. Pesticides might be one of the factors weakening their immune system."
One study by the task force is testing sick bees for pesticides. "We are finding residues of common pesticides and breakdown products of these chemicals. To date over 80 compounds of the 171 in our screening analysis have been found," said Professor Dewey.
"Most are at low levels. Just because they are present does not mean they are at harmful levels. But we do suspect some synergism, where chemicals interact and become a more toxic mixture than either might be alone."
Despite the uncertainty, Germany, Slovenia, France and Italy have banned neonicotinoids. In France, bans have been in place on certain applications since 1999 and clothianidin was never approved because of concerns about the risks to bees.
In September the Italian government banned thiamethoxam, clothianidin, Imidacloprid and fipronil in seed treatments. An appeal by three of the chemicals’ producers was thrown out of Italy’s highest administrative court in January, although it did order the Italian government to set a time limit on the ban.
Dr Julian Little, head of public and government affairs for Bayer, said: "While we welcome the Co-op’s recognition that bee health is important, we are disappointed with their focus. Targeting pesticides is missing the point. In France there has been a unilateral ban yet they still have a problem."
The British Crop Production Council (BCPC), formerly the British Crop Protection Council, agreed: "This is just another example of organisations reacting in an emotive area without reference to the science base," says BCPC chairman, Colin Ruscoe.
He said the "well-documented decline" of honey bees was due to a combination of weather, the Varroa mite and other factors requiring more research. "That is why DEFRA is putting an extra £4.3 million of funding into bee health research. Focusing on chemical insecticides is a red herring which plays into the hand of some disenchanted beekeepers."
Chris Sherlock, the Co-operative’s sustainable development manager, said several factors were likely to be involved. "But we think there is enough evidence to suggest [neonicotinoid exposure] is an additional stress factor and to apply the precautionary principle."
In December, the US Environmental Protection Agency began a review of imidacloprid and is to look at nithiazine in March. All other neonicotinoids will be reviewed in 2012.
The Soil Association has called for a UK ban. In a letter to Environment Secretary Hilary Benn last autumn, it said the chemicals’ use on oilseed rape is particularly concerning because the crop’s yellow flowers attract honey bees.
DEFRA said it would "keep this matter under review" and act "if there is any evidence of an unacceptable risk to bees… at present there is no evidence that the approvals on the crops and the rates used in the UK need to be amended".
Last May, Sainsbury’s launched Operation Bumblebee, a three-year project with pesticide maker Syngenta and fruit and vegetable growers which aims to boost bumblebee numbers in the UK by 600%. It is establishing new bee habitats by sowing and managing field boundaries and is using a seed mix to help give a consistent supply of pollen and nectar.