Dave Goulson, professeur en biologie et auteur : “Le déclin des insectes menace notre existence”

Dave Goulson

Dave Goulson est professeur de biologie, spécialisé dans l’écologie et la conservation des insectes. Il enseigne à l’université du Sussex, en Angleterre. Il a publié plusieurs livres, A Sting in the Tale (2013), Gardening for Bumblebees (2021) et Silent Earth: Averting the Insect Apocalypse (2021).

Your most recent book, Silent Earth, is about insect conservation and the threats facing the natural world. Can you tell us why you felt it was needed and summarize the state of biodiversity at the moment?

We’re in a biodiversity crisis. I think everyone accepts that, although I don’t think everybody grasps the scale of it. Species are now going extinct faster than they have for 65 million years – since the meteor wiped out the dinosaurs.

The book is about why insects are amazing and wonderful and really important – the world wouldn’t work without them, they recycle, they keep the soil healthy. They do all sorts of things that are vital and that we depend upon and sadly, they’re disappearing. The evidence is patchy, but all the evidence we have suggests that insects are declining rapidly.

The drivers are manifold, habitat loss, intensive farming and pesticides are bound to be playing a significant role, climate change, light pollution, invasive species and so on.

And what can we do about it?

There are two real areas: One is niche, but nice, the area of urban wildlife conservation: what we can do in our gardens, which is a good way of getting everybody involved in looking after wildlife. But it is quite small scale because most of the wild land in Europe is agricultural land, and that’s the more challenging area. How do we make farming more sustainable and produce food and feed the world without wiping out biodiversity and undermining the very basis of our farming system? This seems to be exactly what we’re doing at the moment.

If we were to carry on the current trajectory of using pesticides, what would be the consequences?

The extinctions that we’re already seeing will accelerate. Perhaps more important than extinctions is the loss of bio-abundance; organisms that used to be common are becoming rare and therefore the things that [these organisms] do aren’t being done adequately.

We’re already seeing yields of insect pollinated crops suffering because of the lack of pollination, and if pollinators continue to decline, that’s going to mean lower yields, less food for us to eat and it will push up food prices.

And so it could be us out pollinating in the fields?

Well, either that or another option that people are exploring is trying to build robot bees to pollinate crops for us. But it seems crazy when you think that’s going to require more resources, more energy, because they literally have to build trillions of these things to pollinate the world’s crops.

And they’re not going to pollinate all the wildflowers, because we’d obviously programme it to pollinate crops not flowers, so flowers will all disappear. In reality, the practicalities of it don’t make any sense when we compare it to real bees that are very good at pollinating and they’ve been doing it for 120 million years.

Do you think there’s been too much focus on bees as pollinators? It’s not just saving the bees, it’s saving everything?

Firstly, people tend to focus very much on honey bees. A lot of people don’t realize that there are 25,000 species of bee, all of them pollinate, and they think it’s just one.

We tend to forget about all the other pollinating insects and there are thousands and thousands of them. It’s hard to say exactly how many species pollinate but I saw a recent estimate that says there are maybe 6,000 species of pollinating insects in the UK alone, and only 260 of those are bees.  

There’s also a danger that we focus on pollination as the only important thing that insects do, but actually insects do a lot of other stuff that’s less well-known, less glamourous, like recycling cow pats, which the public are much less aware of, but are all really important.

If we adopt more sustainable farming practices, the concerns are that this will lead to such high yield drops that it will jeopardise food security.

We can’t do it overnight. Indeed, the farmers need support in changing what they do. There’s a whole toolkit of ways to control pests that don’t involve pesticides. Ideally, if you’re going to use pesticides at all, you use them as the last resort.

The current farming system is staggeringly inefficient. We grow roughly three times as many calories in the world, as we require to feed everybody, but about a third of that food goes to waste and another third is used as animal feed.  

Overall, about 80 per cent of the world’s farmland is devoted to animal production, which is just really inefficient as a way of feeding people. If we ate less meat and wasted less food, we could put up with slightly reduced yields.

The EU wants to reduce pesticide use by 50 per cent by 2030 to slow down biodiversity decline. Is that enough?

I think we could probably easily go further. There’s quite a bit of evidence that suggests multi-pesticide use is not actually increasing yield at all.

Probably some pesticide usage could be done away with immediately without any drop in yield and farmers would be better off. I think 50 per cent is a good start, if they really get there, but I don’t think it’s anywhere near enough. One of the problems with setting these targets is that it’s very hard to know what it is you’re measuring.

What are you reducing by 50 per cent? Is it the number of times you spray or the weight of stuff you spray or what? And weight isn’t a very good measure because the toxicity of different pesticides varies enormously. You could replace a chemical that’s relatively less toxic but used in larger amounts, with one that’s more toxic but used in lower amounts and the situation would be made worse, but it would seem as if you’d reduced pesticide use.

People tend not to like insects. Do you think that’s partly down to the marketing of pesticides?

You see the advertising for pesticides everywhere. It’s not just farmers, they’re sold in every supermarket, in every garden centre. Pesticides are everywhere and we’re all being told that we need them.

It’s a real challenge trying to reign it in. So far, we’ve failed miserably. Rachel Carson [the American conservationist and author] published Silent Spring 60 years ago this year. When she published it in the United States, there were 37 different pesticides available to America’s farmers. Today, there’s over a thousand and that’s just in farming.

The odd one gets banned, particularly in Europe, but every time one is banned, two more pop up to replace it.

It’s not yet an ‘Insect Apocalypse’, but how severe is the situation?

It’s a pretty catastrophic decline. It threatens our existence as we see it at the moment. Biodiversity collapse combined with climate change will greatly reduce the standard of living for future generations if we don’t do something about it very quickly.