From neonics to parasites, pollinators are under assault. New methods of farming to preserve biodiversity may be needed

Of all the environmental issues we face, the fate of our bees seems to have resonated most with the public. In the UK visitors to the Royal Botanic Gardens Kew are getting a dramatic insight into the importance of bees when they step inside a multi-sensory 17-metre high aluminium behive installation, which converts the vibrations emanating from a nearby bee colony into sound and LED light.

It’s not just honeybees that are causing concern - many wild bee populations are threatened; some have already disappeared.

Their decline raises serious questions about the sustainability of our agricultural systems and means we face some difficult - even moral - choices about how our food is produced.

Bees really do seem to be up against it: parasites, like the varroa mite, habitat loss, climate change and a relatively new type of chemical insecticide are all implicated in their decline. But separating out the various potential factors is difficult, and poses a challenge to policy makers.

Concern first focused on the blood-sucking varroa mite, which has spread from the east, right across the world - with the exception of Australia. The European honeybee is particularly vulnerable, as it lacks any natural defences. There are chemical treatments, but some beekeepers are trying to breed varroa-resistant bees. Indeed there are colonies in Sweden and France that have survived untreated and seem to have developed a resistance to the killer viruses that come with the varroa mite.

Swiss researchers who monitor winter losses across bee colonies in 29 countries say they find the varroa mite “almost everywhere” they see colony losses. But their surveys show big variations in bee decline across different geographic regions of Europe from year to year. Last winter, beekeepers lost 11.9% of their colonies. The data are still being analysed but cold weather across parts of the continent may have had some impact, with Ireland and Northern Ireland particularly hard hit.

Habitat is key: if bees don’t have enough food in summer, they can’t survive the winter. The UK, for example, has lost 97% of the wildflower meadows that once would have provided sustenance, and with it many of the specialised bees. Intense agriculture has created sterile landscapes.

The UK has lost 97% of its wildflower meadows

Another factor in the mix is pesticide use. In 2013, the European Union imposed a moratorium on the use of three chemicals called neonicotinoids. These kill insect pests that feed on key crops like oilseed rape. Introduced in the 1990s, they are the commonest insecticides used across the world. Farmers frequently buy seeds coated with a neonicotinoid, which is absorbed as the plant grows. The chemical travels through the plant tissues; pests will die after eating them. But the chemicals also find their way into nectar and pollen - to be picked up by bees and other pollinators.  Using coated seeds - rather than sprays (which are also banned) - means the chemical is applied whether or not there is evidence of a pest problem. 

In 2014 the Canadian province of Ontario joined the EU in banning neonicotinoids. Honeybee colony losses had averaged 34% each winter for the previous 12 years and Canada’s largest province said there was enough scientific evidence to warrant a precautionary approach. Its aim is to see an 80% reduction in the number of hectares planted with neonicotinoid-treated corn and soybean seed by 2017.

Syngenta disputes the ban

The EU ban has angered many farmers, who claim crop yields are adversely affected. Insecticide manufacturers are equally unhappy. Peter Campbell, senior environmental risk assessor at Syngenta says its own studies fail to show the impacts - either in the lab or in the field - that are being reported by independent scientists in Europe. Most of the data, he says, comes from bees exposed at higher levels than would be seen in the field. And he argues money for research could have been better spent elsewhere: ‘This complete focus on neonics has not served our pollinators well, as can be seen by the fact that honeybee colony losses in Europe have not improved since the EU neonic ban.”

Much of the research so far has been done on honeybees, and involves short-term lab studies. Many have shown sub-lethal effects, which may be overlaid on environmental pressures. However, in August, the UK’s Centre for Ecology & Hydrology (CEH) published a correlation study which took 18 years’ worth of data (1994-2011) on 62 species of wild bee, and concluded that the introduction of neonicotinoids in 2002 on oilseed rape crops had harmed wild bees.

Kew’s Hive installation tells the story of bees

They calculated an average decline of 13% in the geographical spread of wild bees: bees that collected pollen in oilseed rape fields were three times as badly impacted as those that did not. The fact that bees not known to forage on oilseed rape were also affected suggests other routes of exposure - perhaps through dust from seed drilling (which has been observed to kill bees in the Canada), or chemical persistence in soil affecting other flowering plants.

One of the authors, Ben Woodcock, says the study is: “An important piece of evidence. On its own any piece of correlative work is just that, but when added to all the other pieces of work, short term and long term, then [we can] say neonics are having impact at national scale in a wide range of species.”

Campbell does not agree that the study has established a link between neonicitonoids and bee mortality. However, Syngenta is working with CEH on a pan-European field study - designed and run by the scientists at CEH - to assess the impact of neonicotinoids on honeybees and wild pollinators. Results are expected by the end of the year.

The UK’s Brexit vote raised fears that the government will ultimately roll back on environmental protections - especially as it opposed the EU ban on neonics on economic grounds. Last year, the UK permitted some emergency exemptions for oilseed rape and sugar beet. However in 2016 applications were refused on the grounds that farmers hadn’t shown that the chemical intervention had had a positive impact on yield.

The new Defra minister, Therese Coffey MP, was pressed on this issue at her recent appearance in front of the environmental audit committee. The UK, she said, supported the precautionary principle, but “often it’s about how you then make judgements based on it.” She noted that “the EU has a hazard-based approach and we have a risk-based approach”, and a balance had to be struck between the two.

In 2014 Defra launched a strategy to raise awareness of what pollinators need in order to thrive, and set up its own hives on the roof in Whitehall as part of that commitment.  A national beehive count begins this winter, to assess honeybee populations and their health across the UK.

Oilseed rape yields were higher in the year after the EU ban came into force

Integrated crop management

Friends of the Earth campaigner Sandra Bell wants to see farmers adopt other approaches to pest prevention. Ironically, oilseed rape yields were higher in the first year after the EU ban came into force. This may have been linked to milder autumn weather, but it demonstrates that seed treatments aren’t always necessary. 

“Returning habitat to farms could actually help to solve the pest problem, by putting back natural predators.” Farmers trying this have noticed their return, she says.

Indeed last year, the CEH reported that creating wildlife habitats by taking 8% of land out of production could actually improve crop yield, through increased levels of pollination and natural pest control.

Another option is the “trap” crop, which is intended to be attractive to pests, in theory lessening their impact on the main crop. There have been some mixed results with this method and more research is needed.  Such techniques are part of what’s called integrated pest management. It has been compulsory to apply IPM for all crops across the EU since January 2014 as part of attempts to make insecticide use a last resort. Because growers pick and choose elements, Defra says it’s difficult to assess overall UK uptake of IPM measures.  However, Bell doesn’t believe this has increased since neonicotinoids were banned. 

The European Food Safety Authority is reviewing scientific evidence about the effect on bees of the three banned neonicotinoid seed treatments. Its recommendations on whether or not to continue with the ban are due next January. It says any consideration of alternatives or impact analysis is for the European Commission. 

Neither Campbell nor Bell thinks the ban will be lifted - although for very different reasons.  However, Syngenta has just seen the EU approve its Cyantraniliprole insecticide, another systemically acting chemical. Member states have been asked to pay particular attention to the risk to bees.

Woodcock, the CEH entomologist, points out that if neonicotinoids are banned they will have to be replaced. What’s needed, he argues, is a much more holistic view. “Agricultural land is there for production but we need to preserve biodiversity: we need a more constructive debate.”

The impact of insecticides is a matter of fierce argument
Environment  bees  biodiversity  climate change  honeybee  pollinators  research  Brexit  economy  Chemicals  sustainability  agriculture 

comments powered by Disqus