Health

What Happens When All the Bugs Die?

You’ve probably seen the newspaper headlines heralding an “insect apocalypse.” Some accounts are more measured than others, but the underlying studies are quite grim, especially for a bee ecologist like Dave Goulson: Three-quarters of an insect population in this area disappeared in half a century; two-thirds of that one over there; 90 percent of this species, which perhaps you might remember from your childhood but is almost impossible to find in the wild now.

I first met Goulson while working on a story about the fate of bees and what is often called colony collapse disorder. It was both a very real thing — bee colonies kept dying off, largely because everything about industrial agriculture was so brutal and disruptive to them — and a sort of floating symbol of late-Obama-era environmental anxiety. “It just chimes with people — that these stories of bee declines are a symptom of something broader that’s wrong with the world,” Goulson told me in 2015. “They think, if we can save the bees, we can save the world.”

His new book, Silent Earth, strikes a decidedly less cheery note. Its title echoes the warning of Rachel Carson’s Silent Spring, the seminal environmental treatise published in 1962. Amid chapters celebrating insects, analyzing the causes of their declines, and suggesting a kind of road map back to population stability, it includes a dark interlude sketching out what the world might look like if all the trends that have produced these population crashes are allowed to continue.

Let’s start with that bleak vision of the future you stuck in midway through the book. It’s not just the result of insect declines, though those play a part.
I guess I was trying to articulate what I fear might happen — will happen — if we don’t get our act together. The essential point is that if we don’t change direction, then our children are going to have a much tougher life than we’ve had. They’re going to be living in a world with lots of its resources used up, lots of its natural beauty gone. And life’s going to be pretty tough.

The section is set in 2080, narrated from the perspective of your son. He’s gardening for his own food, hand-pollinating each plant and urinating on compost to add necessary nutrients to the soil. The useful insects are gone, but the bad kind — mosquitoes spreading malaria, other pests spreading other diseases — have reached plague proportions. The global food supply has collapsed, and your son guards the garden, circled by sheep-fencing and barbed wire, with a rifle across his knees. The obesity epidemic is a tragically distant memory, and he forages for nuts in the nearby woods.
To many people, it sounds absurd when you start talking about societal collapse. But, of course, every society that’s gone before ours has collapsed. And people counter that by saying, but it’s different this time. You know, we have all this knowledge and technology and capability that we didn’t have before. It’s now a global civilization rather than a more local one. And that’s all true, but I don’t think that necessarily makes us immune.

And you’re absolutely right, the scenario is not driven by insect declines alone. But all of these big environmental issues are interrelated, and it’s the combined effect of all of them that is really going to be devastating. Scientists in particular tend to be in their little silos, focused on climate change or biodiversity loss or soil health or whatever it might be — overfishing and so on. But it’s when you put them all together that you think, Well, hang on a minute, what kind of world are our children and our grandchildren going to be living in?

What kind do you think?
Well, even with climate change — we’re beginning to recognize the severity of climate change at least; it’s getting political recognition at long last. But even climate change is not being dealt with, as you know — the politicians are happy to say there is a climate emergency and several governments around the world have signed up to that, but then they don’t really act on it. And climate change is really the only one of these big issues that has been properly recognized.

There are all of those cartoons that were drawn in the pandemic — one tidal wave labeled COVID-19 followed by one labeled RECESSION followed by CLIMATE CHANGE and then BIODIVERSITY COLLAPSE. How do you see the relative scale of these threats?
I think biodiversity loss, particularly the loss of insects, is probably just as serious as climate change. Of course, the two go hand in hand. They’re driven by many of the same factors. And the solutions probably could be common, at least some of them — reducing deforestation being an obvious example.

And we’re not actually doing anything meaningful to combat climate change, let alone the other big issues that are facing us. I think it’s entirely likely that, unless we’re much cleverer than I think we are and we can come up with technological fixes for all the problems we’re creating, the future is really potentially bleak.

By which you mean …
I think it’s entirely plausible that we are now living in the most comfortable conditions that people will see for a very long time.

You know, you could say we’ve kind of lucked out — being born in the Western world in the late 20th century. It may well turn out to be that we had the best lives. Life before us was definitely harder, and life after us might well be a lot harder too. Of course, it doesn’t have to be that way. This is what’s so frustrating — we can fix all of this stuff, more or less, if we really try. And then everyone can have a decent life. But we have to take it seriously and actually be prepared to make some sacrifices and act, which, at the moment, we’re not doing.

I found your discussion in the book of the legacy of Rachel Carson really quite powerful on this point, as well as depressing. We remember her as almost a mythic figure, the godmother of the modern environmental movement, someone who almost single-handedly changed the way that people in countries like ours think about our relationship to the natural world — someone who, through a kind of moral exhortation, really changed the course of human history, at least when it came to pesticides. But, as you point out, while there was an effect on DDT use in particular, the much broader crusade Carson was fighting in Silent Spring was quite clearly lost, not won.
Yeah. I mean, industrial agriculture has progressed down the same route, through the 20th century and into the 21st century, with ever bigger fields, fewer farmers managing their land with less manpower and bigger machines and more chemical inputs. It seems to have been a relentless process.

We’re now up to, roughly estimated, 3 million tons of pesticides being used every year by the world’s farmers. And many of the products being used are much more potent than the ones that were available when Rachel Carson was alive. DDT seems quite innocuous in many ways compared to some of the insecticides that are available to farmers. DDT is certainly thousands of times less poisonous to insects than its replacements.

Which suggests that, as you say about governments and climate change, that there’s a real difference between acknowledging or even conceptualizing a problem and really doing the things we need to do to solve it. In fact, it may often be the case that that acknowledgement functions almost like an excuse for not taking action.
And the scale of repeated use of pesticides is just staggering. In the U.K., each field is treated 17 times. That could be 17 different pesticides used once or one type of pesticide used 17 times. But basically the fields are just being treated over and over again with chemicals designed to kill either insects or fungi or mollusks or weeds.

And the effects aren’t linear, right? It’s not like we’ve reduced insects 17-fold as a result. Because they’ve grown resistant to these chemical assaults, which means we have to just keep using more of the stuff.
The pest insects are remarkably adaptable creatures. The irony in all this is that the only insects we would like to truly take out are the very ones we can’t get rid of.

What do you mean?
There are so many species of insect. They’re always going to be a few winners. But it’s going to be crop pests, things like mosquitoes and cockroaches and house flies — those are the ones that thrive. House flies are already much more abundant now than they were before people came along because of the huge amounts of dung and rotting waste that we produce. And certain other types of insects will undoubtedly be around, too. They aren’t all going to go extinct. There’ve been some slightly silly reports in newspapers — projections that if insect declines continue, there’ll be no insects left by the end of the century. Those projections are clearly daft because I don’t think there’s any doubt at all that some insects will be here after we’re gone. But it’s unlikely to be bees. And the ones we’d like to hang on to are the ones that are disappearing.

Why is that? Why are the bad ones doing okay? 
It’s because they breed fast, and they are big populations, so they can evolve really quickly. And so they do become resistant to pesticides, which is part of the driver for using more and more pesticides more often. But this was familiar to us even as early as Rachel Carson’s time. It was clear then that that part of the problem was that you start out using a pesticide and you can use a small amount and it’s effective, but within a couple of years, you have to apply twice as much. And before you know it, you’re having to apply several different chemicals to get the same control you were getting with one to start with. So it’s a kind of endless treadmill, or an arms race, which just involves more and more chemical inputs.

Just a few weeks ago, I came across an amazing example of the almost obscene scale of pesticide use. Apparently, this year, 2.6 million acres of Montana are being sprayed from the air with insecticides to control native grasshoppers — 2.6 million acres — I mean, it’s just a staggering area, right? I live in Sussex, in the U.K., and if I remember correctly, it’s five times the area of the county of Sussex — the whole lot being carpet bombed with insecticide to control one species of insect. Now, there are probably 50,000 species of insects living in Montana.

Wait, what’s the problem with grasshoppers? I’d have thought of them as being relatively benign. 
You’d think. But basically they compete with livestock for grass, and apparently the weather has been really favorable to grasshoppers breeding. So the federal government is planning to basically bomb the hell out of the place with insecticide, and there are other other plans to spray other states as well. And it just struck me as, you know, completely insane and disproportionate and just ridiculous, this idea that we have to try and kill and control everything with such indiscriminate tools, which will probably kill countless trillions of insects as collateral damage. Small wonder the monarch butterflies are heading fast toward extinction if we’re doing that kind of thing. It’s like we haven’t learned anything from Rachel Carson at all, as far as I can see.

And, of course, all this stuff has an effect on human health, too, because it gets into our food and sort of gets into us as a result. But you mentioned the monarchs. Your book is about the broader phenomenon of insect decline. Could you just walk me through the top-line figures — what scale of population collapse are we talking about?
The first thing to acknowledge is that the data are very, very patchy and the knowledge gaps far exceed the parts of the picture we filled in, basically because there are so many species of insect and so few monitoring schemes in place. So we have no long-term monitoring data from anywhere in Africa, pretty much anywhere in Asia or South America — and, of course, those are probably the places with the highest insect diversity in the world. Almost all the data we have is from North America and Europe. And even then there are many, many insect groups which aren’t being monitored. But all of that said, we do have some really good long-term studies usually focused on particular groups and almost all of them show rates of decline, some of them really quite precipitous.

In the book, I believe you estimate the total decline at 75 percent over the course of your lifetime.
Insect declines really became a topic of conversation for the general public in 2017, when the German insect decline study was published, which showed this 76 percent decline in German nature reserves in the biomass of insects. And everybody then was talking about, you know, is this happening everywhere or is this something really weird happening in Germany? In the U.K., we have only got really good population data for butterflies, which are dying by 50 percent since 1976, and moths, which are dying by a little less than that since about the same time.

That’s the benchmark for most of these surveys — the 1970s.
Most of the monitoring schemes from around the world start at the earliest in the ’70s or ’80s, yeah. But there’s a really interesting study from the Netherlands where they use museum records to try and piece together likely ranges and population sizes of butterflies further into the past. And that suggests that the insect decline or butterfly declines in the Netherlands were actually fastest in the first half of the 20th century and have slowed down a little since then. That suggests that, for example, the German study and the U.K. butterfly studies are actually just describing the tail end of a much longer and perhaps much bigger decline.

That makes sense to me in the sense that, especially in Europe and North America, where this data was being collected — those are places that have seen over the course of the second half of the 20th century into the 21st century some amount of regreening, reforesting, even rewilding. It’s not the same environment that we had 300 years ago in those places, but overall, there’s been some recovery wild space and forest cover, which might at least soften the curve of some of these declines. But in other parts of the world, where they’re still doing a lot of development and deforestation and ecological destruction, we may be in a much steeper part of the curve.
You’d think so. Certainly in Europe, which is the place I’m most familiar with, we spend a lot of money now on subsidizing schemes that are meant to increase biodiversity. But wildlife is still seemingly declining rapidly despite that expenditure. But it’s very concerning that we essentially have no data from Brazil, for example, which we know is being devastated. We can see the forest disappearing from satellite photos day by day. One can only guess that that must be having absolutely profound impacts on biodiversity. It’s just not being documented.

When I first saw these studies, five years ago, my own instinct was to say, I don’t doubt this particular finding about this particular nature reserve or whatever, but given what I know about how dependent the whole planet’s ecosystems are on insect life, it just didn’t seem plausible to me that we could be seeing such rapid declines without also seeing enormous disruptions further up the food chain. I mean, a 75 percent reduction over just 50 years and possibly a much steeper more dramatic decline over the course of a century and a half — those are really really dramatic declines! So are these ecosystems more resilient to these disruptions than a layman like me might think? Is it possible these data sets are overstating the decline? How would you answer someone like me asking, naïvely, how could this be happening with the rest of the world still chugging along rather than ending?
Well, firstly, there’s this really interesting issue about the whole shifting baseline thing. You know, we struggle to perceive these long-term changes because you can’t really remember things very far in the past. Our own memory is constantly revised so that we think the world used to be more like what it is now. And so each generation has a completely different perception of what is normal.

I come up against this with climate change all the time, and some of the social science I’ve read suggests that we build those baselines just over ten- or even five-year timelines. So what was normal 15 years ago, not to mention 50, plays almost no role in our perception of change. 
That sounds quite plausible to me. Which suggests that it’s possible the world really has changed very profoundly, and we’re just struggling to notice it. The windshield phenomenon is one of the only ones that your average man in the street or woman in the street has noticed because people don’t pay much attention to insects, and we can’t really remember how many butterflies there were when we were children. But people do remember the fact that their windshields used to be covered in splattered insects, if they’re old enough. I think you need to be at least 40 or perhaps more like 50 to really remember this fully. But I’ve met so many people who can recall a time when, literally, you couldn’t see where you were going and you had to stop.

But to the bigger question, why haven’t we seen a bigger impact if insects have really declined so much? Why are we not already seeing repercussions of that? Well, actually, we are. For example, in bird populations, most insect-eating birds have declined. Birds have declined generally. Vertebrates have declined. If you pull off the WWF and the Zoological Society of London’s state of nature reports, they reckon that vertebrate populations are down by, I think, 60 percent since 1970. And insect-eating birds in particular have declined disproportionately. Things like barn swallows, spotted fly flycatchers — they were common when I was a kid. I can’t remember the last time I’ve seen one. Their populations are down, I think, 90-something percent.

You and I first spoke when I was working on a story about bees and colony collapse disorder, which is just a reminder that none of the farms we have today can really survive on natural pollination. They need to import pollinators to fill in the gap, which is why beekeepers drive these huge 18-wheelers all over the country, moving from farm to farm, hiring out their bees to pollinate crops that, in another era, would’ve probably been perfectly well-pollinated by the insects in the local ecosystem. 
And that’s a really risky strategy. Although there are enough honey bees at the moment to deliver that service, it’s not far-fetched at all to imagine a time in the near future when that might not be the case.

So, what would that lead to? We talked earlier about the future we might be facing if we don’t get a handle on all of these ecological challenges. But, just as a thought experiment, what if we did manage all that other stuff but the insect declines continued — what would that mean for us? What would the world look like with just a tiny, tiny fraction of the insects there were in the world of our grandparents?
Well, the impacts of declining pollination on food production is the aspect that is best understood. I’m sure you’re familiar with the figures, but the importance of pollinators to humans is, you know, three-quarters of the crops grown in the world need pollinators to give a full yield. And although those three-quarters of our crops only account for about 30 percent of our food by weight, it’s most of the more nutritious stuff that we eat — most of the fruits and vegetables. A lot of nuts depend upon insect pollinators, too. So with a growing human population, it’s really hard to see how that’s all going to stack up. If our population is going up but yields of fruits and veggies start to drop, then that is going to push up the price of food. And it won’t necessarily be the Western world that suffers first, of course, because we will still be able to afford to buy food. But it will create food shortages in poorer parts of the world.

And how close would you say we are to that? Are we already there? 
I mean, there’s no doubt that yields of some crops are already lower than they should be or could be. For example, apples in the U.K. — the yields are suppressed most years because there aren’t enough pollinators.

And this has produced some extreme things. I’ve seen hand pollination of crops in southwest China, in Bengal in India, with passion fruit in Brazil. It seems like something that’s only going to increase over time, and a declining food supply as our population grows — it’s not going to work out well for us.

We’ve touched on a few of the drivers, but can you walk through the various causes of decline and maybe even rank them in importance?
A lot of this is guesswork, but habitat loss is probably the biggest factor, as with most wildlife declines. The biggest driver of insect declines globally right now is loss of tropical forests.

But it’s quite hard to disentangle habitat loss from the effects of pesticides, certainly in a European context, because a lot of habitat loss is intimately interwoven with increasing use of pesticide — the habitat loss is due to intensive farming. So the habitat loss is going hand in hand with more use of not just insecticides but herbicides and more fertilizer. People interested in farming and its impact on insects have mostly focused on pesticides, but fertilizers can have really profound effects on plant communities by allowing a small number of weedy plant species to thrive at the expense of everything else. And the amount of fertilizer going on farmland around the world is just completely staggering. And there’s also interesting evidence that herbivorous insects do much less well if they’re feeding on plants that have been fed elevated levels of fertilizer.

Then there’s climate change, which is starting to kick in and probably will soon overtake some of the others. Until recently, it was probably fair to say there wasn’t much evidence that climate change had really impacted insects, but that’s changed recently. Light pollution is an interesting one. There’s a growing body of research on that suggesting it has all sorts of interesting and sad effects disrupting the life cycle of the insects — if they emerge at the wrong time because of artificial lighting. It can also disrupt navigation. And there’s disease, which we’ve really only studied in bees, but is undoubtedly contributing to declines, too. So that’s a bunch of factors, and I’m sure there are one or two more that I’ve forgotten and others we haven’t discovered yet.

And is the project of stabilizing those populations just a matter of reversing all of those trends?
There isn’t a simple answer. One way of putting it is that if we accept that insect declines are being driven by lots of different factors, then anything we can do to mitigate or reduce any of those factors will help. Insects might be able to cope with some of these impacts, but not all of them at the same time. But there are some things to do — tackling pesticide use and reducing pesticide use, though that’s a thorny problem because you’re up against the many lobby groups and the challenge of feeding everybody.

And that I think is, for me, perhaps the biggest challenge facing mankind essentially at this point in history: Can we come up with a way of growing food that is sustainable and doesn’t wipe out biodiversity and damage the soil and pollute the air and the sea and everything else? We have an industrial-farming system that we just can’t carry on with because it’s not sustainable. But there are lots of different visions as to how we might do things differently and no real clear consensus and not much investment in that area, which is something we desperately need.

Is that what you’d focus on, if you were some sort of global insect czar?
If I was miraculously in charge of these things, I think we just need to set aside more space for nature. Insects will look after themselves if we just give them a bit of space.

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