• Blind Action Is not Helpful

    Is the number of flying insects really decreasing? Some studies seem to suggest that it is. Now it is important to find out the causes.


Scientific Root Cause Analysis Instead of Blind Action

Did the windshield of your car stay clean and free from flying insects this summer? These days, we frequently read that this is the most obvious symptom of the massive fall in the number of insects which we can all observe at the moment.

Christian Maus

Christian Maus

Global Lead Scientist Bee Care at Bayer AG

Frankly, I have not seen this yet on my car. And I can also not help having the impression that this is a case of subjective perceptions that are gaining more and more weight through constant repetition and retelling – like a snowball that rolls down the mountain and finally becomes an avalanche. Such anecdotal impressions are natural to people. Everything was better back then, Christmas was lovelier, summer holidays were longer and, of course, there were more insects on windshields. These are individual observations and subjective impressions, not solid science. However, our standard at Bayer must be solid science.

We are therefore taking a closer look at the data and facts on the subject of the decline in the number of insects. They do indeed suggest that there has been a drop in the number of flying insects in Germany over the last 30 years.

The most significant source of data to be evaluated to date are the results of measurements by a Krefeld-based group that studies insects. Since 1989, the researchers have been setting traps that take samples of flying insects in a variety of areas, primarily in nature reserves in North Rhine-Westphalia. Originally, the purpose of this was not to take systematic records but after a certain period of time, the sample collections caught the attention of the researchers because the volume of insects in the traps was falling.

This was a very interesting but worrying discovery. However, it cannot be interpreted without further information. The reason for this is that the study was not designed from the outset to systematically record the development of biomass in the traps at the various locations. Therefore, from the beginning, the traps were not set at the same locations every year. Naturally, this would have been done differently in an appropriately designed scientific study. This deficiency is therefore one of the main points of criticism of the study, and in terms of content this criticism is deserved. However, in terms of the original intention of the study, it is not completely fair. Sometimes in science, you find things that you were not looking for. Of course, the correct methodology for analyzing the data can also be debated, and rightly so. Depending on the calculation used and from which chronological reference point you are working from, you will arrive at the 76 percent decline that the Krefeld group found, or a lower figure. However, it appears probable that a decline, regardless of how large it may be, has taken place, even if the 76 percent is probably not representative for all of Germany.

The crucial question now is: what are the factors that caused the decline in biomass of flying insects? The entomologists’ study does not answer this question. Interestingly, the declines did not appear to correlate with factors that you might immediately expect, such as certain types of habitat, changes in land use, or climate change. Other factors, such as intensive agriculture and crop protection were not investigated by the researchers and they are also careful not to speculate here. In any case, the question arises of whether crop protection is the most plausible explanation as a cause, because the decline was observed primarily in nature reserves and not in areas of intensive agriculture.

However, it should be noted that immediately after the data emerged, interested groups, not necessarily scientists, very quickly knew the answer without even having detailed knowledge of the data. Naturally, their theory was that conventional agriculture in general and chemical crop protection in particular were behind it all. Such reflex accusations are, of course, ideologically motivated and have nothing to do with fact-based arguments. Some people even said that enough was known about the cause of the decline that other investigations into the causes were no longer necessary; the only thing that remained was to act. Further scientific research cannot, of course, serve as an excuse to delay or even block necessary action. But acting on the sole basis of dubious facts that are not supported by data is blind action for the sake of it. Interpretations of scientific study results that are colored by ideology help the ideologists but not the insects. In addition, root cause analysis and action are not a mutually exclusive, either-or choice. There is nothing wrong with conducting research where there is a need for clarification or with taking action once well-established, goal-oriented options for action have been identified.

We at Bayer do both: on the one hand, we test measures which encourage and sustain insect diversity in today’s countryside and, on the other hand, we conduct and support studies that aim to help to establish the causes of the decline. We are not interested in identifying who is to blame and supporting a specific ideological world view, but instead, in bringing facts to the table and finding the best solutions.