Researchers warn: Without Insects nothing works
Dragonflies, bumblebees, beetles & co. are vital for our ecosystem. Experts reveal what threatens them and what you can do about it.
“My friends” is what I affectionately called them as a child. If I stood still, they would sit on the palm of my hand and we would enjoy each other’s presence. At least that’s what I liked to think in my childish imagination when I watched hoverflies. They can do up to 300 wing beats per second, allowing them to hover in one spot in the air for long periods of time – and also giving them their name. They are also true flight artists over long distances: Numerous hoverfly species migrate to the Mediterranean region every fall – and even cross the Alps on their way! Because of their black and yellow stripes, they are often confused with wasps. The truth is, they are completely harmless: they have no sting – just a good strategy to protect themselves from predators.
Insect population down 80 percent
Many people have already noticed that there are far fewer insects stuck to the windshield after a car ride today than there used to be. That the forests have become quieter and the meadows more monotonous. Today, we encounter insects mainly as annoying mosquitoes or wasps in the summer. Since 2017 at the latest, it has been clear that these are not just vague assumptions. That’s when the “Krefeld Study” appeared, a long-term investigation that has since had a wide impact. For more than 27 years, the Entomological Association of Krefeld used insect traps to capture flying insects in various nature reserves in the Rhineland. The data were analysed by scientific teams. Caspar Hallmann and his team made an alarming discovery: the population of flying insects had declined by around 80 percent since 1989. And from all corners of the world we hear news confirming the insect die-off.
In the case of hoverflies, the situation looks particularly dramatic: Around a third of the 463 species found in Germany are endangered. And in 2020, a study from the Swabian Alb revealed that migratory hoverflies have declined by up to 97 percent over the past 50 years.
No ecosystem without insects
Now, five years after the study, I have an appointment with Caspar Hallmann from Radboud University in Nijmegen for a phone call to learn about his current research. You can hear his enthusiasm about the insect world in almost every sentence: “Insects are involved in pretty much every part of the ecosystem, apart from the deep sea,” he says. “Our ecosystems can’t function without insects.” That’s because insects are part of many natural processes, he says: They pollinate more than one-third of our food crops and three-quarters of all wild plants. In doing so, they make it possible for a large part of the plant world to reproduce in the first place. And then they clean up the mess: They turn fallen leaves back into nutrients and decompose the carcasses of dead animals.
And they eat pests. The larvae of the hoverfly, for example, like to fill their bellies with aphids. A single hoverfly larva can eat several hundred aphids in its lifetime. That’s why they are welcome visitors to farmers and gardeners – and I learned years after my childhood encounter with hoverflies that they are indeed our “friends.” Conversely, insects themselves are also an important part of the food chain: many other species feed on them. It is therefore not surprising that, because of insect declines, insectivorous birds are also in decline.
Everything in nature is interconnected
“I understand that insects – apart from a few butterflies – are not very charismatic,” laments Caspar Hallmann, “but nothing works without insects, it’s as simple as that.”
“The little things that run the world,” is how biologist Edward O. Wilson once aptly described insects. More than a million species have been described to date; in Germany alone, the number is estimated at around 35,000 insect species. In comparison: Birds occur in 500 species in Germany. “That’s when you realize that when you talk about biodiversity, you’re actually talking about insects – at least in terms of the diversity visible to the naked eye,” says Caspar Hallmann.
Species diversity is so important because everything in nature is interconnected: every species has its function, every species is dependent on others, every species is connected to other species through the food chain. The more different species there are, the more resilient and productive ecosystems are.
But even independently of this, species possess a value in themselves – a fingerprint of the Creator. “Because of us, thousands of species can already no longer glorify God with their existence, nor communicate their message to us. We have no right to do so,” wrote Pope Francis in his encyclical Laudato Si.
Arable land offers no food for insects
But what is it that is causing such hardship for our little flying friends?
The overall picture is still not entirely clear, but researchers are gradually putting the pieces of the puzzle together and revealing what could lead to this dramatic insect die-off. The most important factors are certainly habitat destruction and fragmentation, and intensive agriculture. Where 100 years ago diverse village structures with small fields, hedgerows, orchards, and colorful meadows predominated, today arable land stretches to the horizon – as far as the eye can see nothing but corn, wheat or sugar beets. Food supply or habitat for insects? Not a thing. In addition, beneficial insects such as hoverflies no longer exterminate aphids in these green deserts; instead, pesticides are used – chemical substances that kill organisms to prevent damage caused by insects, fungal infestation, or weeds, for example.
Insects are often narrowly specialized
As a result, the species diversity of arable weeds has declined by 70 percent since 1950. Many weed species that were once very common are now virtually extinct. The lack of plant diversity naturally has an impact on insects. Some insects are so narrowly specialized that they can live on only one or a few plant species. If they die out, the insects die with them.
The bloody-nosed beetle, for example, feeds exclusively on cleaver. It defends its favourite food with brutal methods: If someone disputes its herb, it chokes out a reddish poison. Unfortunately, this does not help it against the destruction of its food plant by humans.
Weeds help the animals
Bärbel Gerowitt, professor of phytomedicine at the University of Rostock, sums it up in her dry, humorous way: “The insects are more likely to starve than be sprayed to death.” An agricultural scientist, she conducts research at the Institute of Land Use at the University of Rostock and was also my professor and mentor there during my studies. I ask her about how agriculture can help restore insect life. “I think the best way to actually do something for insect diversity is to have a lot of crop diversity,” she explains, “that you grow crops that are beneficial to insects.”
That might include protein crops such as peas or lupines, whose flowering provides food for wild insects. And in fields with crops that don’t directly benefit insects, such as wheat, plant diversity should still be allowed in the field. “I think we’re going to come around in agriculture to accept some loss from weeds, too, because insects are so important to us.” Flowering strips on the edges of fields help, as does subdividing large agricultural areas into smaller fields, between which hedgerows or flowering areas would be created. This is because, in addition to the amount of food available, continuous plant corridors also play a role: many insects simply cannot bridge large distances.
Light harms nocturnal insects
Agriculture is practiced on almost half of the total area in Germany, with arable farming taking up about 70 percent of the land. That’s a large part of the country where insects hardly find any habitat. And things usually don’t look any better on the rest. In addition to the emptied landscapes, the sealing of soil also steals space and food from insects. According to the Federal Statistical Office, an average of 52 hectares of land are converted into settlement and traffic areas every day throughout Germany: Asphalt deserts that are anything but insect paradises.
And they bring with them so-called light pollution: artificial light from the illumination of streets, buildings, but also private gardens has fatal consequences for nocturnal insects. And that includes half of all insect species. A study by the Leibniz Institute found that the artificially illuminated night disrupts the natural orientation, foraging and reproduction of many insects. This makes me think of the huge, glaring neon sign that shines into my apartment and the nearby park every night. I wonder if a friendly letter of complaint can bring about the nightly shutdown. Politicians seem to have recognized the need for action. On March 1, 2022, the Federal Nature Conservation Act in Germany was tightened. For the first time, the term “light pollution” is mentioned as a constituent element. In nature conservation areas, there will be a fundamental ban on new street lighting and on illuminated advertising installations.
Politics has big plans
Invasive species are also problematic for some insects. In parts of South America, for example, the European bumblebee, which was introduced there, has completely displaced the local large bumblebee species Bombus dahlbomii – and brought with it in tow a pathogen that is dangerous for bees. When invasive plant species displace native plant species, insects that specialize in these native plants no longer find food. Climate change, with changing rainfall patterns, heating and droughts, is also affecting some insect species. In the tropics, for example, it is probably now simply getting too hot for many insect species. In the end, it is probably the combination of all these factors that is leading to the current collapse.
In the coalition agreement of the German “traffic light” government, biodiversity is described as a task for humanity and an ethical obligation. Environment Minister Steffi Lemke speaks of an “age of renaturation” that is being ushered in. By 2030, organic farming is to account for 20 percent of all agriculture and pesticide use is to be reduced by 50 percent. A new concept for EU agricultural policy is to be developed so that subsidies are no longer awarded solely on the basis of area, but are linked, for example, to biodiversity measures such as flower strips.
When I ask Bärbel Gerowitt whether we’re on the right track, I get the sobering assessment: “We’ve put on our shoes – but we haven’t set off yet.” After all, writing a declaration of intent is one thing, but then implementing it is quite another. So we can be curious to see how much impetus will really come from politics in the next few years.
Anyone can help
There are many ideas. In France, the sale of pesticides has only been permitted to registered farmers since the beginning of 2020. That means they will no longer be available for landscaping and private gardens. Green roofs also help insects. Here, politics could make specifications and lead the way with their own buildings. Green spaces in cities should be protected or, if possible, expanded, and parks should be planted with native flowering shrub and tree species. British conservationist and biology professor Dave Goulsen writes in his latest book, “Silent Earth – Why We Must Save the Insects” (Hanser): “Recent research shows that the most effective way to increase insect diversity in cities is with allotments and allotment gardens.”
This also means we can all put on our shoes and start marching. If you have a garden, you can create habitats for as wide a variety of insects as possible: plant native flowers and hedges, leave foliage and dead wood as winter homes and breeding grounds, allow wild corners with dandelions and nettles, mow less frequently, put up insect hotels, and build gravel-and-sand mounds in sunny places as insect castles. Dry stone walls – walls built of loose stones – or cairns also provide certain insect species with the safe haven they need.
More praise for farmers
Besides putting up flower boxes, a city dweller can make a difference through his or her shopping and eating habits. I ask Bärbel Gerowitt again: How can I, as a consumer, contribute to insect-friendly agriculture? “The first thing I would always say is: eat as little convenience food as possible. A bit more still comes to farmers from food that is natural than if it is heavily processed.” In other words, with a bag of chips or frozen fries, the amount the farmer gets is much less than with a bag of potatoes. Organic food also helps insects: “There are enough studies to say that biodiversity is greater on organic fields,” affirms Bärbel Gerowitt.
And the scientist, who herself grew up on a farm, has one last important piece of advice for me: If you live in the countryside, you should show appreciation for farmers. Because currently they get to hear criticism and reproaches from all sides, she says. “But the more negative feedback they get, the more they orient themselves to the self-image of ‘I’m a good entrepreneur,'” Bärbel Gerowitt points out. The less they’re valued for providing and maintaining the landscape, she says, the more thoughts like, “People don’t like me anymore, but at least I’m making decent money” play a role.” Showing interest in them, also wanting to understand their situation and listening to their concerns, is important, she says: “There’s a lot of potential in that, I think. It’s okay to criticize farmers, but they should also hear positive feedback and feel that they are part of the village structure with their way of doing business.”
Vote for the Golden Beetle
The U.S. biologist Paul Ehrlich once compared species extinction to removing rivets from the wings of an airplane. The plane will still fly for a while, but at some point it will crash. Without insects, our system Earth cannot exist. But we can still turn it around – right through our villages, our cities, our gardens. For this, they need our voice and our action. Because the great golden beetle and the small red damselfly, antlion and sand wasps, large banded grasshopper, green forester and all the other species that are threatened with extinction cannot speak for themselves. They depend on us to stand up for diverse landscapes, strong villages, regional and organic agriculture, and insect-friendly communities. Then the buzzing and humming will be preserved.
What actions would you like to take or are you already taking to help insects? What gives you hope for our biodiversity?
This article was originally published in print in the andersLEBEN Magazin (May 2022 issue). It was also published on FOKUS Online (8.7.2022).
