Insect collapse – an underestimated phenomenon

In recent months, it has been repeatedly reported in the media that insect populations are declining. We asked Sven Bacher, professor at the Department of Biology, what he thought about the insect collapse and asked him about the causes and tips for action.

Mr. Bacher, why should we concern ourselves with the insects?
Most people do not know that ¾ of all species in the world are insects. They therefore represent a large part of the biomass and occur in almost all habitats where they perform different functions. We often speak only of “pollinators”, but there are also “decomposers” that decompose dead material. Microorganisms convert this decomposed material into nutrients for plants. Insects also serve as food for other animals or control species to prevent pests, for example. They regulate e.g. parasites and plant pests. Although there is no equilibrium in nature, as is often stated in textbooks, insects nevertheless provide a certain stability. Two years ago there was a first public outcry about insects because a German research team found out that more than 80% of all flying insects in German nature reserves have disappeared within a few decades. In January, another article was published, which again caused a lot of media interest. In it was described that world-wide the insect populations decline.

What are the causes of this decline in insect population?
There are a number of factors which have an influence and which affect the various insect groups differently. What worries me lately is the accusation that science is reduced to giving simple explanations of complex issues. We have to accept that certain things have complex causes. Insect collapse is a good example of this: it is not a monocausal phenomenon and we have not yet been able to identify the causes with certainty.

However, pesticides are often named as the cause.
Exactly. It is an issue that can easily be addressed at the political level. However, we have little evidence of the extent to which pesticides are responsible for insect decline. We do not yet have any hard data on this. In the laboratory we can easily show that insects die from pesticides. This will also happen in nature, but whether there are fewer insects as a result, we cannot say definitively. There were no pesticides in the German nature reserves, and yet populations have declined. In the media, however, pesticides have been stylized as the main cause – a problematic argument.

Bee decline has been a much discussed topic since the film “More than Honey”. What do you think about this?
Albert Einstein once said that first the bees die, then the humans. In our latitudes, bees are the main pollinators of cultivated plants. However, honey bees are almost 100% controlled, i.e. they are bred and cared for by beekeepers. The film “More than Honey” shows exactly this industry in the USA. Because it is an industry, we don’t have to worry that the bees will die out. New bees can simply be bred. We should talk much more about natural pollinators like wild bees. There are interesting studies that show that wild bees pollinate more than honey bees. The death of wild bees would therefore be more serious.

What would be the consequences?
For example, a loss of food. However, scientists do not agree on the magnitude of the impact, as many of our global food crops – such as rice, corn and wheat – do not require insect pollination.

Why did this issue become so popular?
In my opinion, the problem is not the death of honeybees, but the destruction of the insects’ food supply. The bees are taken only emblematically as representatives for the destruction of nature, like the panda or polar bear in the 1990s. The bee is instrumentalized because it appears in children’s books and people can identify with it. The bee is a “good” insect and politics can be made with it. Nobody would react if we talked about soil mites. For example, such mites and hundreds of other “crawling animals” ensure that the soil has food and plants can grow. The “ugly” insects are probably much more important than the bees or beautiful butterflies. We should therefore pay more attention to these groups.

Why is climate change more popular than loss of biodiversity?
On climate change, we have clear and simple messages: Global warming must not exceed 2 degrees Celsius. People understand this information and can talk about it. Biodiversity, on the other hand, is spongy and researchers have not yet succeeded in formulating simple messages. As I said, they have tried pandas or polar bears, but these are not the “big” problems.

What are the “big” problems?
Insect collapse is already a big problem. Insects have many functions. But when we say “insects are dying out”, we bring together many insect species with many different functions. It becomes diffuse and therefore the consequences are difficult for many people to grasp. As I said, there is speculation about the causes of insect decline and the use of pesticides is often cited as a reason. This reason will apply to some insects, but not to all of them. The same is true of intensive agriculture or increased construction activity, which is depriving many species of their habitats. Virtually all usable areas in Switzerland are populated by humans or used by agriculture. We have an enormous influence on biodiversity.

So insect collapse is caused by humans?
Actually, it’s all due to man. There are no grounds for hope that these are natural fluctuations. As far as biodiversity is concerned, we simply still have very little concrete data showing the direct influence of humans. We can simply confirm climate change with global physical measurements. Biodiversity is more difficult. We do not know how many species there are on earth. But we know that we are losing species a thousand times faster since man has been on Earth. In addition, species are dying out faster than we can describe them. We have no idea about microorganisms. We see strong and rapid changes in our environment, but we do not know the causes and effects. It would be sensible to slow down and limit changes.

How does the temperature rise affect the insects?
Global warming is a global but heterogeneous phenomenon. It will therefore not become warmer in all regions. Switzerland is one of the countries that will become warmer above average. As the temperature increases, precipitation will also increase here. This is a good sign for agriculture and plant growth. In future, we will be able to produce more on the same land. In contrast to African countries or Pakistan, for example, we will be the winners of global warming. For insects, this can mean anything. In recent years, we have observed an increase in Mediterranean species in Switzerland, such as the wood bee. In Switzerland, we have also noticed a shift in species to higher altitudes. The treacherous thing about the mountains, however, is that they become pointed towards the top, reducing the area available for habitats of many species. When they reach the top of the mountain, they become extinct. It also becomes more difficult for species that depend on each other, e.g. by pollination. Without their respective pollinators, which have been displaced by climate change, plants dependent on them will also die out. Even with the pests, their natural enemies have to migrate with them in order to regulate the populations.

Opponents of climate change argue that plants grow faster due to the increased CO2 concentration. Why doesn’t this line of argument work?
Plants actually grow faster, but they absorb fewer nutrients and trace elements. The overfertilization by CO2 leads to a dilution of the nutrients, i.e. the food quality of the plants decreases. CO2 is nothing more than fertilizer. This can have consequences for the species. Half a year ago, a paper was published with the statement that pests in particular will benefit from global warming. They can settle and spread better. Switzerland will also be affected. Insects will have a direct impact on humans.

What can we as individuals do against insect decline?
There are a number of things we can do as individuals. Extensive agriculture allows for more biodiversity than intensive agriculture. As consumers, we should buy extensively produced products or organic products. We then support this type of production. However, you have to be careful when you shop in the supermarket: The extra margin on organic products is often used for cross-financing ordinary products. It is therefore advisable to buy directly from the producer or in a pure organic shop.

However, we must first know about such aspects.
Exactly. We generally need to better understand what biodiversity is good for, what it does and how much of it we need. Some people say that they don’t need biodiversity; others think that every species has a right to life. We probably have to find ourselves in the middle of these extremes and justify why we want this. Of course, we must also be aware of the consequences. Those people who want to protect all species have to accept that this would require a drastic reduction in the earth’s population. There is conflict at every wishful thinking. We must be aware of what we are acting for: Do we want to preserve nature in an “original” state or only ensure the survival of mankind? These questions are not addressed explicitly in society even though it would be so important.

Sustainability is currently on everyone’s lips and many people are committed to positive change. Is this change becoming noticeable?
Time and again international environmental agreements are signed, but so far nature has benefited little from them globally. Even how we act as individuals is not effective. Many people think that if they use an energy-saving lamp and recycle their waste, they have almost saved the world. It’s just a “psychological Band-Aid” and many people aren’t aware of that.

Do we therefore need regulations for a positive change?
Absolutely. The environment is a common good from which everyone benefits, including those who place a heavy burden on it. In Switzerland, people often appeal to personal responsibility in order to protect the environment. But if your neighbour is flying to the Caribbean, why shouldn’t I do the same? Why should I do without? When it comes to common goods, it is wrong to insist on the common sense of the individual. We need rules that apply to everyone. It is obvious that few will change their behaviour if the general public does not participate. This is an economic law: when it comes to common goods, individual initiatives are useless. So if we want to change something, we need laws. There are social issues that must be discussed. We must also be aware of the consequences – for ourselves and for our children. We must all act. There is no excuse.

The interview was conducted by Anna Zikeli and Kerstin Bütschi.


Prof. tit. Dr. Sven Bacher is Professor at the Department of Biology at the University of Fribourg. His research focuses on ecology. He deals with all applied aspects of ecology, focusing on harmful organisms and alien species.

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