Many of us can remember when summer evening car journeys featured large numbers of insects caught on the headlights and windscreen. Clearly, the number of insects has declined drastically, and the reasons are commonly acknowledged: loss of insects’ food sources, use of pesticides and agrochemicals. We are witnessing a poisoning of our countryside on a scale greater than Rachel Carson described in Silent Spring – her classic exposure of the first generation of synthetic pesticides.
Everyone has heard that we need bees and other insect pollinators to ensure our food crops. Yet insects are important for more reasons than this – they are a vital part of our ecology, pollinating wild plants, and taking their part in the food chain, for example providing food for insectivorous birds like swallows and swifts.
Neonicotinoids are designed to kill insects. Loss of insects leads to loss of birds – and other wildlife too. Neonicotinoids are highly toxic for aquatic life. So we all need to know more about them.
Nicotine is a toxin that plants such a tobacco Nicotiana tabacum produce to protect themselves from insect damage. Nicotine acts on the central nervous system of insects, causing paralysis and death. Nicotine has effect on mammalian nervous systems too, acting as a stimulant and relaxant – that is toxic in large doses.
Man-made neonicotinoids, literally ‘new-nicotine-like’ chemicals, have been manufactured since the 1990s, and are widely used in farming, as well as by gardeners. They are ‘like nicotine’ because they act upon an insect’s central nervous system.
There are seven different neonicotinoids made by major companies, and marketed under various names. For example, Imidacloprid is made by the German corporation Bayer, and is now probably the most widely used insecticide worldwide. Sussex-based Syngenta makes another widely used neonicotinoid.
Thiacloprid (also Bayer owned) is the active insecticide in Provado – on sale widely throughout Monmouthshire, and as it says on the bottle ‘Provado Ultimate bug killer’. Just a few moments consideration should be long enough to realise the impossibility of creating an insecticide that kills only what we regard as ‘bad’ insects, and leaves the ‘good’ ones unscathed! How could that be? Insecticide manufacturers like to use the term ‘bug’ – hoping and apparently succeeding in making the gardener believe that only ‘bad’ insects will succumb.
None of us would like to think that we are responsible for the decline of honey bees, bumblebees, butterflies or farmland birds, but the research evidence suggests that we are. So please leave those aphid killers and rose treatments on the supermarket shelf. Would it not be wonderful if Monmouthshire could emulate Seattle and become a neonicotinoid free County?
Neonicotinoids are now used worldwide in the commercial cultivation of the vast majority of fruit and vegetables, including apples, cherries, berries, greens, tomatoes, potatoes, wheat and other cereal grains, and oil seed crops.
They are used as seed coatings – this means that the seed is coated with a covering of fertiliser and the neonicotinoid. As the seed germinates and grows, the whole plant contains the neonicotinoid, and it can be found in every part – stem, leaves, flowers, nectar and pollen. This is the meaning of the term ‘systemic’ and it means that insects feeding anywhere, at any time of the plant’s life, will be killed. As insects forage on the flower, they too will inevitably take up some of the neonicotinoid.
Just as it has been difficult to pinpoint exactly how nicotine causes cancer (and nicotine is still not classified as a carcinogen), so too is it difficult to prove cause and effect with neonicotinoids. In sunlight, pesticides gradually break down into a range of metabolites that have more or less toxic effects than the original compound. Insects are therefore exposed not just to one, but rather to a cocktail of different pesticide toxins. It is this cocktail of chemicals, collected during the normal foraging activity of bees and other insects, that leads to unknown lethal synergies. A combination of sub-lethal effects that together have lethal consequences. In honey bees the effects might be to make the bees more susceptible to viruses, for the queens to be weaker, or for the bees to have impaired cognition – this was one of the first symptoms for honey bees – recognised first by French beekeepers, who noticed that when their bees were foraging on sunflower that had been treated with ‘Gaucho’ (Imidacloprid) – the numbers of bees in hives dwindled because bees could not navigate their way home. French beekeepers were therefore the first in Europe to call for these chemicals to be banned.
There is now a significant body of research evidence, sufficient for the EU to ban the use of neonicotinoids for two years from December 2013. Earlier this year DEFRA was lobbied to lift the ban and permit planting of treated oil seed rape again this autumn. This first request was rejected, to be quickly followed by a second, smaller scale request – which was approved. It appears that commercial pressure has won over scientific evidence.
It is not just insects that are suffering from these potent toxins: a study in the Netherlands by Radboud University published last July in the Journal Nature, showed that the level of neonicotinoids in environmental samples correlated strongly with the decline in populations of insect-eating birds. Also last year a comprehensive worldwide assessment concluded that systemic insecticides pose a serious risk for a wide range of non-target invertebrates, even when present below expected environmental concentrations.
We all need to know about neonicotinoids and see them banned as soon as possible.
- This article has also appeared in the Monmouthshire Meadows Group newsletter. Find out more about Monmouthshire Meadows Group
- Find out more about the neonicotinoid debate on the BBC Countryfile website
- Find out more about the Radboud University study mentioned above and published in the Journal Nature: ‘Declines in insectivorous birds are associated with high neonicotinoid concentrations’