Neonicotinoids - What are they, who uses them and should they be banned?
Neonicotinoids (neonics) are chemical insecticides - used to kill a variety of pests such as aphids (greenfly and blackfly) and root-feeding grubs. They act as a nerve poison on the insect, causing paralysis and eventual death.
There are a number of varieties of neonics, but all are systemic pesticides ie they are absorbed by the whole plant and transported to all its tissues (from root to flower) including the pollen and nectar. This affects bees and other pollinators, as well as worms in the soil, birds from eating the seeds, and aquatic life from the run-off into rivers and streams.
Why should we be worried?
Prof David Goulson, of Sussex University, writes
“The toxicity takes your breath away – just five maize seeds treated with neonicotinoids are enough to kill a grey partridge.”
Neonics are used on a vast scale by farmers worldwide. Virtually 100% of the corn in the US, Canada, Australia and China is treated. In the UK, before the EU ban in 2013, much of the oilseed rape was treated with neonics to prevent flea beetle damage. It is usually applied by coating the seed before sowing. Unfortunately the sowing process often damages the coating, and releases a dust laden with poison. The toxin remains active in the plant as it grows, and stays in the soil for up to 10 months - often longer if there are repeat crop sowings year on year.
Gardeners also use neonics. Sometimes deliberately – as a rose spray to kill greenfly – and sometimes inadvertently, as many potted plants have had their soil treated with neonics to prevent grub or weevil infestation. These poisons are also in nearly all bulbs, lawn treatments, and possibly (and somewhat ironically) in the plants sold as 'Bee Friendly'. They are used by commercial growers as sprays on apples, pears and a range of greenhouse crops. Cat and dog owners use neonics when treating their animals for fleas.
To ban or not to ban?
The major concern is for bees and other pollinators. Large scale treatment on agricultural crops is potentially devastating. An IUCN report highlights the “significant damage to a wide range of beneficial invertebrate species and is a key factor in the decline of bees.” The report argues that, "far from protecting food production, the use of neonics is threatening the very infrastructure which enables it.” Other research has shown the devasting effect on bees - see Further reading for a selection of research papers, including this most recent review from The Centre for Ecology and Hydrology which indicates that bees which forage on oil seed rape crops (such as the buff tailed bumble bee) are three times more likely to be at risk than those which forage elsewhere.
In 2013 the EU banned the use of just 3 types of neonics for 2 years (there are many neonic formulations created by the large international drug companies such as Bayer, Dow and Syngenta.) Despite the ban, yields in the UK did not go down. On the contrary, oil seed rape yields over 2014 and 2015 have actually gone up. But in July 2015, the UK government responded to a plea from the NFU to lift the ban to ‘protect’ the new season’s planting of oil seed rape in five English counties. In 2016, the government turned down the NFU request to lift the ban, citing technical problems of containing the pesticide to specific areas (not of the pesticides themselves) .
The organic solution for gardeners
There is absolutely no need for nicotinoids in our gardens or allotments. Garden Organic strongly opposes their use.
“Organic growing is based on the interdependencies of life forms,” says James Campbell, Chief Executive. “If we poison insects indiscriminately – including bees and butterflies - we risk poisoning other animals in land, air and water. It is, in the truest sense, not natural.”
Here are some tips for the organic grower to reduce aphid damage without using neonics:
- Encourage natural predators such as birds and parasitic wasps. Birds should be fed and watered during winter and have plenty of nesting areas. Parasitic wasps love cow parsley, dill and fennel flowers.
- Transplant seedlings in early summer, when they are strong enough to resist attack from aphids, which are at their peak in high summer.
- Do not over feed crops with nitrogen. This encourages green sappy growth loved by aphids.
- Use barriers such as fine netting to cover your crops. Install it immediately after planting out young seedlings, before the aphids have hatched in mid-summer. This prevents trapping them inside the netting.
- Use mulches ie light excluding materials, between plants (biodegradable plastic, straw, well-rotted manure or low growing green manures such as clovers). The latter two boost the soil’s reserves, and thereby reduces infections transmitted by aphids.
Here is the IUCN report outlining the global threat to biodiversity from the indiscriminate use of neonics. This is matched by another damning report, which pulls together research papers produced by independent scientists worldwide ie those not sponsored by the agro-chemical industry.
The effect of neonics on bees
- Research shows that neonics affect the bees' ability to forage and pollinate. See this report from the University of Guelph. And this researchfrom the University of Stirling, which shows that bumble bees which have neonics in their system, have difficulty in shaking out the pollen from some plants.
- This paper indicates that one of the neonic chemicals - thiamethoxam - affects queen bumble bees' ability to ovulate
- Of the three banned neonics - clothianidin, imidacloprid and thiamethoxam - recent research has shown that the latter two are more toxic to bees. A field study(sponsored by Bayer) reported that clothianidin was not harmful to bee colonies. However, other independent research from the University of Bern, has shown that the same chemical will reduce the bees' ability to produce sperm.
- PAN (Pesticide Action Network) has produced a number of factsheets on bees and neonics, including one for farmers on how to grow crops effectively without poisonous insecticides.
This study from Dundee University analyses the 3 banned neonics - clothianidin, thiamethoxam and imidacloprid.
This recent study from the University of Sussex links neonic poisoning to the decline in butterfly population in the UK.
DEFRA’s pollinator strategy was created in response to the outrage at the large scale use of neonics. They urge growers to create pollinator habitats adjacent to areas treated with insecticides. However, research from Sussex University has found that the chemicals are absorbed by the wildflowers growing in field margins, thus affecting the insects which visit them. This is correlated by a recent paper from the US, which shows that bees take the majority of their pollen from plants around the crops - ingesting a cocktail of up to 31 different pesticides.
Here is a video of John Atkin, COO of Syngenta, explaining why he thinks neonics are necessary.
And finally, this extensive review, produced by The Royal Society, highlights an interesting research conundrum. Because most research concentrates on honey bees, there is little evidence of the effect of neonics on other key pollinators such as hoverflies - or on worms, slugs, birds and aquatic life. However, the report explains that it is difficult and expensive to do field experiments – pollinators by their nature are wide ranging and variable in their habits. It is these vital gaps in our knowledge which lend more power to the persuasive proponents of neonics.