Neonicotinoids are suspected to be responsible for insect death. Right? The Bayer Group, which developed these pesticides and launched them on the market in the early 1990s, comments on the natur interview.
Bayer has been selling so-called neonicotinoids, a group of insecticides that the company once invented, for around three decades. They are suspected of playing an inglorious role in the worldwide loss of bees and insects. The EU has now banned three out of five neonicotinoids approved in Europe, and scientists around the world are warning of “ecological armageddon”. In the cover story of nature 3/20 (“poisonous seeds”) is accused by the chemical giant of various sides for influencing studies in connection with the neonicotinoids and for intimidating critical scientists and beekeepers. The toxicologist Henk Tennekes even claims that Bayer knew early on about the real dangers of “neonics” for non-pests, but ignored them. As part of this research nature Bayer also asked for an opinion. At the beginning of the year, the pesticide manufacturer agreed to an interview.
It is a bright blue February morning when we take the bus from Leverkusen to Monheim, where Bayer AG’s “Crop Science Division” is based. In the middle of the campus-like area is building 6200, the “Bee Care Center”. Here Christian Maus, Lord of the Bees at Bayer, welcomes us for a chat. Below are excerpts from this interview. The complete interview appears in the April issue of naturewhich will be available from March 20th.
nature: How long does it take until insecticides like the neonicotinoid “Imidacloprid” are approved? And how expensive is the development?
Mouse: In general, the development of a product can easily take eight to ten years. And usually a few hundred million euros are invested. You have to submit many studies to the authorities for admission. Independent scientists, however, criticize that this data is not accessible to them. We launched a transparency initiative in 2017. Since then, you can always find more of these studies on our website www.cropscience-transparency.bayer.com recall.
For the most part, pesticide manufacturers can test their products themselves before approval. There could be a suspicion that Bayer and Co. are issuing their own certificates for the products they bring to the market.
We don’t issue the certificate. We only write the class work. And the tasks of class work are given to us by the regulatory authorities. They specify exactly which studies we have to carry out. Because we allowed to don’t do these studies. We are Committedto make them. It wouldn’t be fair if the taxpayer had to pay the costs.
There have been various studies, for example in France, that suggest that neonicotinoids contribute to bee death. However, you say that there is no connection. How do these researchers come up with this?
What often gets mixed up in the discussion is on the one hand the potential effects that a substance has – and on the other hand the question of what actually happens to it under practical conditions. The fact that a substance has a potential for harmful effects does not mean that it really does damage in reality.
Field studies have also been carried out – in some cases by highly respected organizations such as the French state research institute INRA – to demonstrate that neonicotinoids can have negative effects on bees that you yourself have not encountered before.
We would definitely not say that these institutions make such studies wrong or worse than we do. However, I would like to emphasize that in the case mentioned there are also other studies carried out under more realistic field conditions – and in those then there were actually no harmful effects on bee colonies.
How can you guarantee that the poison of the neonicotinoids only harm the pests and no other living things?
In addition to the bees, the other so-called non-target arthropods are naturally also among the organisms that have to be tested as part of the risk assessment. We have carried out numerous studies on individual species in the laboratory as well as on entire species communities under field conditions. Long-term studies too. On the basis of this data, we can be sure that no unjustifiable damage can occur to these non-target arthropods if used correctly.
The corn rootworm larva, the pest, dies? And the springtail, a very welcome ground dweller, has a bit of a headache, but is he feeling better afterwards?
A springtail is also one of the standard organisms that must be tested for every soil application. And the legislator specifies exactly which effects, which effects are permitted within the treatment area. There will never be a plant protection product that specifically addresses only one species. Therefore, a certain amount of effects on other species is considered acceptable according to the licensing regulations.
What is acceptable What are acceptable damages?
For example, the negative effects on species against which a remedy is not directed must be limited in time. If we bring an agent to the market, we have to demonstrate that any such effects in the treatment area will recur within the season.
Does that mean you think neonicotinoids have no lasting negative effects on bees and other insects other than pests?
Let me put it this way: if used correctly, neonicotinoids have no unacceptable effects on beneficial population or bee colonies that are considered unacceptable by law.
With such a sentence you are legally on the safe side.
Yes well, that’s precise. To put it very clearly: An insecticide naturally has effects against insects. But agriculture is always an interference with nature. That is also the purpose. We primarily want to cultivate certain crops in our fields. And to ensure this, we have to intervene in nature. For example, by clearing the forest to make room for fields. By plowing. By fertilizing. And of course also by applying crop protection. Certain negative effects will never be completely avoided.
Can you briefly explain how neonicotinoids work?
They cause an overexcitation of the nerve cells, which is fatal to the insect pest.
These insecticides dock on and block certain receptors, right?
Yes. However, this bond is reversible, and therefore not final. It can be undone.
It’s very controversial, isn’t it?
We have new data on this, which we will soon summarize in a publication. They prove that it is a reversible, i.e. only temporary, bond.
Would you have been more reluctant to launch neonicotinoids if they had turned out to be irreversible?
If we had found effects that we cannot explain or that make the products unsafe according to legal requirements, we would of course have carried out further studies.
As early as 1991, a year before the first neonicotinoid imidacloprid was approved in the EU, a study was published in a Bayer publication that imidacloprid leads to an “almost irreversible” blockage of the receptors.
Firstly, what is ultimately decisive for the approval of a product is the result of the studies in the approval process. In addition, we are always trying hard to understand the mechanisms behind our products even better, so we do a lot of additional studies – which are not part of the approval process itself. On the other hand, the study you mentioned is around 30 years old. We now know more. We have better data that reflect today’s level of knowledge, and on this basis we can say today that it is not an irreversible bond. I think it’s normal that insights need to be revised because the methods are evolving.
There is now much to suggest that industrial agriculture is making a major contribution to insect and species extinction. Can we continue as before?
I believe that crop protection in the future will be a kind of toolbox. The farmer can put together a tailor-made modular system from new seeds, mechanical methods, but still chemical agents – which can be used more and more efficiently and therefore more economically thanks to digital support – which represents the best balance between effectiveness and environmental protection. We are already doing research in this direction.
This means that you may be foregoing a large part of your previous business model: the mass sale of pesticides.
As I said, agriculture inevitably has an impact on nature. But we have to try to make all the adjustments to keep these effects as small as possible.
Do you also think that these effects are currently too great?
That we want to get better doesn’t mean that what we’re doing now is bad. We always want to optimize. This is not a problem. It is an investment in progress.
Christian Maus, 51, studied biology with a focus on insect science and evolutionary biology at the University of Freiburg. He then did his doctorate there on the molecular evolution of insects. He has worked in various positions for Bayer AG since 2000. From 2016 to 2019 he was the scientific director of the Bayer Bee Care Center. He has been a senior scientist in environmental security at Bayer Crop Science since 2019.