Neonicotinoids and insects

Bees on a honeycomb
The controversy over the effect of pesticides on bees and other insects has been rumbling along for years. This is especially the case for neonicotinoids - or “neonics” - which are sold under trade names including  acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam. Imidacloprid is the most widely used insecticide in the world; you will even find it in anti-flea treatments for domestic cats. These are powerful neurotoxins, synthetic variants on nicotine, that are applied to wheat and oilseed rape seeds before sowing.

Neonics work systemically. As the plant grows, it absorbs the seed coating through its roots and the chemical spreads throughout the plant, protecting it from pests. But this also means that the toxins get into the pollen and nectar of flowering crops. This concern led to the EU banning the use of neonics on flowering crops from December 2013. However, in a pre-Brexit move, Liz Truss, then Secretary of State for the Environment, overturned this ban in central and eastern England in 2015.

There are signs of hope in that B&Q has said that from February 2018 it would no longer sell flowering plants grown using the pesticides. It claimed it was the first retailer to commit to such an undertaking.

In a recent blog Dave Goulson summarised the effects of neonics on bumblebees (https://www.soilassociation.org/blogs/2016/the-toxic-bouquet-pesticides-in-farmland-wildflowers/). Dave will be familiar to many as the author of “A sting in the tale”, a book that offers fascinating insights into the world of the bumblebee. He is a respected bee expert - Professor of Biology at the University of Sussex and founder of the Bumblebee Conservation Trust in 2006. So when it comes to bees, he knows what he’s talking about.

His research has showed that pollen and nectar collected by both honeybees and bumblebees contained all sorts of pesticides; a mixture of several neonicotinoids and a cocktail of fungicides. What was most disturbing was that the majority of these chemicals seemed to be coming from the wildflowers, not from the crop. For pollen collected by honeybees, 97% of the neonics being brought into the hives were from wildflowers, even during the flowering of the oilseed rape that had been neonic-treated. A lot of it was coming from hawthorn blossom.

It’s not known for sure how these chemicals get into wildflowers. But we know that about 95% of the neonics applied to the crop seed goes into the soil and soil water. Residues accumulate over time and leach into nearby streams. They are liable to be sucked up by flowers and hedgerow plants nearby.

Concentrations  of neonics found in bumblebee nests are higher than those that have been found to reduce nest growth and queen production, impair learning and navigation, and cause deaths. Other insects such as butterfly and moth caterpillars are also being poisoned, for if the chemicals are in the nectar and pollen then they are also in the leaves.

As Goulson says “it cannot be good for our wildlife to be chronically exposed to chemical cocktails, and in these circumstances it should not surprise us that our wildlife is disappearing at an alarming rate. What madness has led us to pollute our countryside with persistent, systemic neurotoxins?”

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