Earlier this week, the Centre for Hydrology and Ecology provided the latest twist in the ongoing debate about the impact of pesticides on bees. Their study concluded that half of the decline in the bee populations they observed over 18 years could be attributable to the use of a controversial type of pesticide, neonicotinoids (neonics).
Campaigning organisations like 38 degrees and Friends of the Earth have mobilised significant public support for an outright ban on neonicotinoids. In 2013, a YouGov poll found that 71% of the population would support an outright ban on neonicotinoids.
Given the importance of bees for sustaining our natural environment and our domestic farming industry, the concern is well-placed. The stakes are high for the agriculture sector, as 30% of crops globally depend on natural pollinators such as bees, which are worth an estimated $360 billion to the industry.
The decline of bees
There is a widespread perception that bees are in decline. There has been an observable loss of wild bumblebee species, with two out of 26 species from 80 years ago no longer present in the UK and a further six now found in much smaller areas of the country. Similarly, since the Second World War, the number of honeybee colonies has fallen from 400,000 to around 130,000 in 2013.
However, thankfully, there does seem to have been a very recent recovery in bee numbers: between 2008 and 2012, government figures show an increase in the number of honeybee colonies.
The decline in honeybees has been observed around the world, and is often referred to as ‘Colony Collapse Disorder’. A range of causes have been adduced for this: the Varroa mite, poor nutrition, urbanisation, agricultural intensification, habitat degradation, and climate change.
But some have attributed part of the loss of bees to the use of certain pesticides and, in particular, neonics. First used in the 1990s, neonics are coated on to the seed of crops, such as oilseed rape. The pesticide is then absorbed and transported throughout the plant. This prevents pests, like flea beetle larvae, from destroying the crop.
There is now a significant body of academic evidence showing harmful effects of neonicotinoids on bees. A 2015 study found that the bumblebees’ pollinating services are reduced by exposure to neonics. Another 2015 study, which carried out a large field trial of honeybees that came into contact with neonics, found a correlation between honeybee colony losses and the use of neonics. A 2016 study observed a decline in brood production in colonies exposed to neonics.
The regulation of pesticides is currently an EU competency. Depending on the outcome of the Brexit negotiations, the responsibility for pesticides may be returned to the UK government. In 2013, the EU imposed a moratorium on the use of neonicotinoids, on the grounds that they posed a threat to bees. An EU review on whether to lift the ban on neonicotinoids will be concluded by January 2017.
The UK Government is opposed to the EU ban of neonics. It has published two literature reviews, one from 2012 and the other from 2013, assessing the link between pesticides and the decline in the bee population. They found no unequivocal evidence of ‘sub-lethal’ effects on pollinators. They criticised some of the studies as failing to accurately recreate real-life conditions in the field with laboratory experiments.
In 2013, the UK Government was forced to implement the ban on the use of neonics. But, while they have no choice but to enforce the EU regulation, UK ministers have the powers to grant emergency authorisation for the use of neonics in limited circumstances. They did so in 2015 for around 5% of the UK’s oilseed rape crop, following the advice of their scientific advisory body, UK Expert Committee on Pesticides.
The Government, nevertheless, has shown concern about the bee population, with the publication of a ‘National Pollinator Strategy’ in 2014. The strategy does acknowledge potential adverse effects of unregulated pesticides on pollinators. But its response is only to keep the scientific evidence on pesticides under review. The majority of the proposals involve government working in partnership with farmers, landowners, and beekeepers to improve land management and husbandry practices on a voluntary basis.
There is growing evidence of a causal link between neonicotinoids and bee decline. This week’s study by the Centre for Hydrology and Ecology further strengthens the case. But whether the harm is yet sufficient to merit a ban, or whether the trade-off is acceptable in order to improve crop yields, is a matter of judgement. It is also hard to assess whether it is primarily neonics driving the decline in bee numbers.
Oilseed rape cannot be grown without some kind of pest control mechanism. A vital issue that policymakers must consider is whether the risks of neonicotinoids outweigh the risks of the alternative pesticides. For this reason, the best hope of a solution lies in further research and development of alternative, more sustainable pesticides.
Sam Hall is researcher at Bright Blue