Josef Settele, biologiste et chercheur : « Nous pouvons lutter contre la perte de biodiversité en changeant nos habitudes alimentaires »

Credit: UFZ

Le professeur Josef Settele dirige le département de biologie de la conservation et des systèmes socio-écologiques) au centre allemand de recherche environnementale (UFZ). Il a aussi dirigé l’écriture du dernier rapport de l’IPBES (la plateforme scientifique mondiale sur la biodiversité).

It is said that intensive agriculture and the associated use of pesticides are a major cause of species decline and insect mortality. Is this true at all?

Insecticides kill insects. When they kill, they do exactly what they were invented for. However, the whole landscape is now affected by the substances’ effect, not just the areas where they are originally used. For example, studies have found neonicotinoids in honey from the most remote corners of the world, where they were not used at all. This suggests that pesticides may well play an important role in insect mortality.

In addition, the large monocultures inevitably lead to a loss of diversity because they have few hedges, ridges or flower strips. In our [IPBES] Global Biodiversity Report 2019, we named land use as the number one direct driver.

The loss of insects scares many people. Is it justified? What are the risks of insect decline?

We could lose our adaptability for the future. Just think of the impact of climate change on pollinators: climatic changes mean that certain species can no longer keep up and thus become extinct. Then other species that are better off could take over the role of extinct species. A wide range of species is therefore a kind of natural insurance.

It is difficult to say whether there will be 580 bee species in Germany in the future, as there have been in the past, but the more species there are, the more adaptation options there are. No one can say exactly how many species are needed. We will only know when it is too late.

In the context of insect decline, the decline of pollinating insects plays a special role. Is there a particular risk here?

Yes, that is a big risk. Especially in fruit growing. Around 75 per cent of cultivated plants depend on pollination by animals, mostly insects. And thus also our vitamin supply of fruit and nuts. Only the wind-pollinated crops, i.e. wheat, barley, oats, the whole grains and cassava, do not depend on animal pollination.

Shifts in flowering times and temperature extremes also frequently lead to crop failures. Then a large part of the pollination sometimes falls flat and the species that can hardly cope with heat, for example, especially bumblebees, are poorly synchronised with the ripening cycles of the fruits. Then, in addition to the damage caused by cold and heat spells, the pollinators also fail.

Are there tipping points that make change irreversible, as known from climate research, also for biodiversity?

When a species that has millions of years of evolution behind it is lost, it is a drastic tipping point. From this perspective, we see tipping points all the time. Every day, about 150 species become extinct worldwide. That’s about one species every 10 minutes!

Many farmers and agribusiness groups want to continue farming with mineral fertilisers and pesticides. What would happen if they got their way?

This would put the food security of humanity at risk. A large part of the animal feed used in Europe comes from the Global South, and we use huge areas of agricultural land there. If we continue as we are, we deprive the Global South of using a significant part of arable land that could be used to feed the world. 

What is your solution to this problem?

My answer would be to modify our diet. In Germany, we use around 60 per cent of agricultural land for animal feed, which is very costly in terms of energy. Most of the negative consequences of inefficient European land use are felt in southern countries, not at all in our own. This cannot work globally. If we eat less meat, we have to produce less intensively, because then not so much land is needed for production.

But it has nothing to do with species decline, but simply with land and energy consumption…

Indirectly, yes. We can also solve problems of species loss by changing our eating habits. It depends on which crops we cultivate and where, and whether we establish the biological control systems needed to limit the presence of pests. By protecting and promoting biodiversity, we can produce a greater of variety of fruits for consumption.

Comprehensive EU agricultural reforms were supposed to be presented in March. Then they were postponed with reference to food security in the context of the war in Ukraine. How do you assess the postponement?

The knee-jerk reactions after the war started strike me as something like deciding to set my house on fire when I’m cold to make it warmer. It’s a bit like that when we now use all the fallow land and put reforms on the back burner. The war has shown that many decision-makers have not really understood the importance of sustainable land use and the connection to species loss.