Crop spraying near Harvington, Worcestershire, England. Photo: muffinn via Flickr.com.
Revealed: the chemical blitz of pesticides in our fields
30th January 2014
An ordinary arable field in Sussex is sprayed with pesticides 22 times over a single growing season. Dave Goulson wonders how the bees can survive this toxic onslaught - and exactly who benefits.
It is hard to see how modern farming practices are arranged for any benefit other than maximising agrochemical company profits.
Perhaps I was naive, but when I discovered the extent of the chemical soup applied to typical fields of crops I was astonished.
As part of our ongoing investigations into the impact of pesticides on bees, we looked at twenty five fields containing winter rapeseed or winter wheat during the 2012-13 growing season.
For any particular field, the list of pesticides applied is worryingly long.
These are perfectly normal farms; not especially intensive, situated on the edge of the South Downs in East Sussex, an area of gentle hills, hedgerows and wooded valleys.
Beautiful, rural England - Constable would have liked it here. But let’s look at it with a bee’s perspective rather than a painter’s eye.
A chemical assault course
Let’s look at one fairly typical field. The rapeseed crop, whose flowers the bees will feed on in season, is sown in late summer with a seed dressing containing the insecticide thiamethoxam.
This is a systemic neonicotinoid, with exceedingly high toxicity to bees. Taken up into the plant, detectable levels will be in the nectar and pollen the bees gather.
In November, despite the protection supposedly offered by the neonicotinoid seed dressing the crop is sprayed with another insecticide, the endearingly named Gandalf.
What harm could the wise old wizard possibly do? Gandalf contains beta-cyfluthrin, a pyrethroid. Pyrethroids are highly toxic to bees and other insects - killing insects is their job, after all - but as there should be no bees about in November that shouldn’t be a problem.
The following May, while flowering, the crop is sprayed with another pyrethroid, alpha-cypermethrin. Only weeks later the crop is blitzed with three more pyrethroids just for good measure.
The toxic barrage goes on
That's a real belt-and-braces approach. Why use one when three will do? The crop is still flowering at this point (it was a late year), and will be crawling with foraging bumblebees, hoverflies and other pollinators.
Between winter and summer, the crop is also treated with a barrage of herbicides, fungicides, molluscicides and fertilisers - 22 different chemicals in total.
Most may have little toxicity to bees in themselves, but some, such as a group of fungicides (demethylation inhibiting or DMI fungicides), are known to interact with both neonicotinoids and pyrethroids, increasing their toxicity to bees.
So, when the fungicide prothioconazole is added to the mix tank that includes the year’s final application of chemicals, any feeding bee will be simultaneously exposed to a barrage of three pyrethroids; the thiamethoxam from the seed casing now in the nectar and pollen; and a fungicide that amplifies the toxicity of all these chemicals.
Many unknown factors
We don’t really know what impact this has. Safety tests generally expose test insects to one chemical at a time, usually for just two days, while in reality they are chronically exposed to multiple pesticides throughout their lives.
The fact that bees still live in farmland suggests they’re pretty tough, but we don’t know the effects on other pollinators or wildlife.
The agrochemical industry tell us all is well, but they also tell us, and the farmers they advise, that all these applications are necessary for growing crops, and that without them food production would collapse.
I have my doubts. Is this really how we want the countryside managed? Do we really want to eat food produced this way?
Silent Spring - all over again ...
Fifty one years ago, Rachel Carson’s book Silent Spring highlighted the environmental damage leading from a dependence on pesticides, including poisoning farm workers with the pesticide DDT, now banned in much of the developed world.
A new approach was developed, Integrated Pest Management, or IPM. More of a philosophy than a technique, IPM’s aim is to tackle pest problems using many methods, for example using pest resistant varieties, crop rotation, sacrificial trap crops, and encouraging pests' natural enemies.
Only if all else fails and pests are in sufficient number to cause significant economic damage are pesticides applied.
Everyone agreed then, and still agrees, that this is the best, most sustainable method. But while IPM of sorts is still used in some small-scale horticultural crops, mainstream arable farming has forgotten about it.
Why have we gone back to prophylactic applications of dozens of different toxic chemicals?
A lot of the blame lies with government. We used to have a number of state-funded experimental farms in the UK, where crop research was conducted, and there used to be an independent agricultural advisory service. But almost all have been sold off.
One consequence is that IPM research is not funded - instead the agrochemical industry has been allowed to fill the gap. Now, 75% of agronomists who provide advice to farmers work for agrochemical companies.
Small wonder that farmers use lots of pesticides!
This looks dumb. But then again ...
One major reason not to use pesticides prophylactically - that is, "in case" of pests, rather than as a response to pests - is that pests quickly grow resistant, and eventually the pesticides become useless.
Overuse would seem to be a dumb strategy for the agrochemical industry. But perhaps not.
Each new compound is exclusively manufactured and sold by the company that developed it, but this exclusive right expires after a number of years, at which point anyone can manufacture it.
The price drops, as do profits for the parent company - so it’s not so important if the pesticide has become ineffective. In fact if in the meantime they’ve developed a new product, then it is to their benefit.
Not so good for farmers, on the other hand, who must pay the premium price for each new chemical generation.
So who is farming designed to benefit?
It’s hard to escape the conclusion that current farming practices are not designed to benefit farmers, who pay through the nose for expensive pesticides.
Nor do they benefit consumers, who are offered expensive, pesticide-drenched food. Nor again the environment, which is continually contaminated with a cocktail of chemicals.
It is hard to see how they are arranged for any benefit other than maximising agrochemical company profits.
I think I might head home early today and finish digging over my veggie plot. At least I can control what goes into that.
Dave Goulson is Professor of Biology (Evolution, Behaviour and Environment) at the University of Sussex. He receives funding from Defra and BBSRC.
Also by Dave Goulson in The Ecologist: 'Neonicotinoid ban won't fix all bees' problems'
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