Insect and other arthropod populations are rapidly declining. This alarming loss of biodiversity jeopardises our joy of life. After all, what would the world be like if children grew up without the joy of fluttering butterflies or buzzing bumblebees? But there is more at stake. Our food production depends on healthy and biodiverse ecosystems for pollination and fertile soil. The current EU pesticide regulation completely fails to protect non-target organisms, as was shown in our recent report ‘Licence to Kill’.
In this campaign to protect arthropods from pesticides to restore biodiviersity, we interview scientists, review new scientific research and highlight the importance of lesser-known arthropods. Our aim is to stimulate the discussion to achieve the urgent protection of the natural abundance on which our lives depend.
Who is Dave Goulson?
Dave Goulson (DG): Hi, my name is Dave Goulson. I'm a professor of biology at the University of Sussex in the south of England and I specialize in the behavior and ecology and conservation of bumblebees and particularly the effects of pesticides on bumblebees.
What are arthropods?
DG: Arthropods comprise the bulk of life on Earth. About 80% of all known species. Literally arthropod means jointed feet. So these are little creatures with exoskeletons, jointed legs, the insects, the spiders and other arachnids and the crustaceans which are mainly in the sea and between them they make up the bulk of life on earth. Arthropods are vitally important to all ecosystems.
They make up the bulk of species in most ecosystems and they perform a whole raft of roles. So just quickly they are food for a huge number of larger creatures, birds, bats, lots of mammals, freshwater fish and so on. they recycle dead bodies dung from animals leaves tree trunks and all sorts of other things. And recycling is not very glamorous but it's really important. Something has to do that to release the nutrients back to the ecosystem so that more plants can grow and so on. they help to control crop pests. they help to keep the soil healthy.
They distribute seeds and probably the best known thing that arthropods do is they - insects specifically - pollinate more than 80% of all the plant species on the planet. So that means without the insects most plants wouldn't produce any seeds and would ultimately go extinct, which would obviously be catastrophic. There's a direct human link here, of course, which is that threequarters of the crops we grow in the world need pollinating by insects to give a good harvest. So, we're directly dependent on those pollinators for our well-being.
How big is the role of pesticides in the worldwide decline of insects?
DG: There are lots of drivers of insect decline. We know for example that habitat loss has played a big role. Climate change is starting to impact them. Light pollution affects nocturnal insects. Invasive species had an impact. But probably one of the biggest drivers is the way farming has changed. It's become much more mechanized and much more reliant on chemical inputs.
So where farmland a 100 years ago was a relatively wildlife friendly biodiverse habitat, today farmland is almost devoid of any kind of wildlife including insects. And a big driver of that of course are insecticides which are routinely applied to crops multiple times per year and insecticides are designed to kill insects. So, if you spray the landscape with insect poison, shouldn't really be surprised if insects decline. it's kind of almost inevitable, however carefully you do it. it's hard to say exactly what proportion of insect declines can be attributed to insects to pesticides because insecticide use is wrapped up in a whole system of farming. and almost every aspect of that is harmful to insect life.
What are the consequences of this insect decline?
DG: Because of the ecosystem services that insects provide the recycling of nutrients, keeping the soil healthy, helping to control pests and so on. Insect decline has really obvious and concerning consequences for the viability of terrestrial ecosystems and particularly for farming. Without insect pollinators then all the insect pollinated crops will produce reduced harvests. Without natural enemies of crop pests, we'll have worse pest problems which will ravage the crops into the future. Without invertebrates keeping the soil healthy, crop yields will fall.
So the short answer is that insect declines are going to make it really hard to feed everybody and the human population in the future is likely to struggle unless we do something to turn around these declines.
If we continue to do this, where are we going?
DG: It's quite scary imagining where we're heading if we don't change direction pretty radically. we're in the midst of an accelerating extinction crisis globally.
Species are going extinct faster than they have done probably for 65 million years since the meteor wiped the dinosaurs out. So we know that it's estimated that species are going extinct at least 100 and perhaps a thousand times faster than the average historic rate and that's accelerating. And on top of that of course climate change which is a kind of interact another huge environmental problem. Biodiversity loss and climate change go hand in hand and each exacerbates the other. Between the two of them it's a pretty bleak future for our children if we carry on down this route.
We’re looking at the collapse of food production, the collapse of terrestrial ecosystems and everything they do for us. And also, aside from the sort of the practical implications, wouldn't it be sad if we lose the amazing biodiversity on our planet? Imagine our children living in a world without butterflies or bees or birds or flowers. It's just utterly depressing. It's kind of unthinkable. what are we doing? We should regard the planet as our most valued possession and yet we're just being incredibly reckless and destructive.
Why is biodiversity not protected by pesticide regulation?
DG: The regulatory system for pesticides has just repeatedly let us down. It has failed to detect pesticides which turned out to have environmental impacts when they were used by farmers at a landscape scale. There are lots of examples. If you look at the history of pesticide use, which goes back to the 1940s, most pesticides that have been manufactured have eventually proved to be harmful and end up being banned. Then they're replaced by new generations of pesticides, which we're told are fine until after 20 years we discover that they're not fine, and we ban those.
And so we're just in this kind of cycle of round and round replacing one pesticide with another. The regulatory system which is supposed to prevent harmful pesticides ever being used by farmers simply is ineffective. It's repeatedly failed us. because it's not rigorous enough. It ignores too many other factors that are really important in determining the environmental impact of pesticides.
What are the biggest flaws in the current practice?
DG: There are so many flaws in the regulatory procedure at present. It is quite hard to know where to start in terms of a critique, but let me give it a quick shot. So firstly it focuses on death as the main endpoint that's measured in and usually in short-term trials in the lab. It ignores sublethal impacts. So, for example, if you're testing the effects of a pesticide on honeybees, you dose your honey bee and after, say, 48 hours, you assess, is it alive or is it dead? If it's alive, then everything's fine. The bee be able to fly, might not be able to navigate, might not be able to learn, might not be able to do any of the things that a bee needs to do. Its immune system might have been blocked. but that isn't assessed.
So that ignores a huge raft of really vital effects of pesticides on insects. But then there's the other things. The system looks at short-term exposure, usually one dose of pesticide when in actual fact we know that non-target insects are continually exposed to pesticides probably all of their life at varying doses. And that isn't captured at all by the current system. Then we've got the fact that that insects are exposed to cocktails of chemicals which is not evaluated and we know that sometimes those chemicals can act synergistically. So the effects are not additive, the presence of one pesticide can greatly exacerbate the toxicity of another pesticide. That's all completely ignored by the regulatory system.
The tests tend to be done on the active ingredient and not on the formulation that's actually used. Just to give you an example, glyphosate is not very toxic to bees in its pure form. But as formulated in Roundup, which is what farmers actually spray on their fields, it's much more toxic because the formulation farmers use has lots of extras added to it which are designed to increase its effectiveness. And in this instance, they seem to massively increase its toxicity to insect life.
Couple more problems with the system is if that isn't enough, it always looks at healthy organisms. So you take a healthy honeybee for example and you expose it to pesticide. Does it die? In the real world, organisms are also being stressed by other things. They might have a disease. They might be coping with heat stress. There's a really interesting recent study that showed that at elevated temperatures, pesticides become more toxic. That's not captured by the regulatory process.
And then finally, the regulatory process only looks at a handful of species. So with bees, it tends to look at the honey bee and it assumes that the effects on a honeybee are the same as the effects on every other type of bee. That's actually obviously not true. The honey bee is a pretty weird and atypical bee and probably isn't representative of all the others. Of course, you can't test every species, but you could certainly test more than we do at present. So basically the current system is just woefully inadequate.
What do you think of the concept of recovery?
DG: The idea that non-target insects will just bounce back, that you can kill 50% of them and they'll just recover is clearly nonsense. Not least because all the evidence we have is that insects are declining. So clearly they're not bouncing back at a landscape scale. And that's no great surprise because most insects have a relatively small number of generations per year. So for example, most butterfly species, they have one generation per year. There isn't time for the population to recover. If you knock it out, even if you just spray an insecticide once a year, that's going to completely wipe out the population. It has no ability to recover. And one of the sad realities is that so called pest insects are the ones that will bounce back. It's well known that you get a thing called resurgence. If you spray a crop, you knock out the pest that you're targeting and you knock out the natural enemies of the pest. The pest can breed really fast. Pest insects tend to have a short generation time, high fundity. They produce lots of offspring really quickly. So they'll recover.
But the natural enemies tend to have a much slower population generation time. So they're much slower to recover. So the pest will often get worse after you spray pesticide because there are no natural enemies left to control them. And just to give another example, in orchards, earwigs are important controllers of small insect pests, things like aphids. Earwigs have just one generation a year. the females make a little nest in the spring. If you spray an orchard with insecticide, you wipe out the earwigs and it can take them many years to recover. And yet if you support a healthy population of earwigs, you don't spray them. They do the equivalent amount of pest control of three insecticide sprays per year, all provided for free.
The long story short, basically most non-target insects don't recover fast enough if you wipe them out with insecticides.
What do you think of the concept of ecosystem disservice?
DG: The idea that there are ecosystem disservices has been around for quite a while. It used to be used to describe any insect which is essentially harmful from a human perspective. But this new approach seems to be grouping whole clusters of similar insects together and marking them as either good or bad providing services or disservices. And I gather grasshoppers are regarded as providing a disservice as just one example. Grasshoppers can be crop pests. They're not usually very important crop pests in Europe. Obviously in Africa, locusts can be serious pests, but in Europe, we don't suffer from grasshoppers as insect pests, and they're hugely important as food for a whole raft of organisms that we might care about. Lots of birds feed on grasshoppers, small mammals, and so on. So if we treat them as being undesirable and don't care about what happens to them, that's going to have on ramifications for biodiversity more generally. So that seems like a really clumsy approach to me.
How can we protect biodiversity?
DG: If we want a regulatory system for pesticides that actually does the job, that actually stops the registration of pesticides that are going to harm the environment, then it needs to be more rigorous. The whole system needs to be improved. It needs to include sublethal impacts and cocktail effects and chronic exposure. It needs to look at the real formulation of pesticide that farmers spray, not just the active ingredient. It needs to look at more organisms. That's going to make it more expensive. but I'm sorry if that's what it requires to make it safe, then that's what we have to do.
A better regulatory system means it will cost more money to bring a new pesticide to market. And the pesticide industry tried to claim that we wouldn't have any new pesticides if we had a more rigorous regulatory system. I have to say I just don't believe that. We have a lot of pest pesticides on the market at present in Europe alone about 500 different pesticides. We're not short of pesticides. But we are short of insects and biodiversity. it's free falling. So at the moment the balance seems to be far too much in favor of allowing easy registration of new harmful pesticides and nowhere near enough in favor of actually protecting the environment which is what the system is supposed to do.
