Insects in nature conservation areas - buffer zones could minimise pesticide exposure

Insects in nature conservation areas are heavily contaminated with pesticides. This is shown by a study recently published in the journal "Scientific reports". It is part of the interdisciplinary research project "DINA - Diversity of Insects in Nature protected Areas", which is funded by the Federal Ministry of Education and Research (BMBF). The Leibniz Institute of Ecological Urban and Regional Development (IOER) contributed to the study with a spatial analysis. It shows that insects in nature conservation areas could be better protected from pesticides by additional buffer zones.

Over the past three decades, more than 75 per cent of the insect biomass in German nature conservation areas has demonstrably disappeared. Experts suspect that pesticides are one of the main causes of this dramatic decline. So far, however, they have not been taken into account in protected area management, risk analyses are lacking and conventionally pesticide-managed farmland is located in the middle of protected areas or surrounds them.

As part of the DINA project (Diversity of Insects in Nature protected Areas), nine partners, including the IOER, have been investigating insect diversity in nature conservation areas in Germany for four years under the leadership of NABU (Nature And Biodiversity Conservation Union). In a recent study, they have now taken a closer look at the pesticide exposure of insects. For the first time, the research team from the University of Koblenz-Landau responsible for this part of the study used a newly developed method to investigate the extent to which the insects themselves are contaminated. The data collected in 21 representative areas across Germany clearly show that insects in nature conservation areas are contaminated with a cocktail of pesticides. The researchers analysed data collected in the protected areas in May and August 2020. The method used makes it possible to detect 92 common agricultural pesticides.

The researchers found 47 pesticides in the insect samples. On average, they were able to detect 16 different pesticides on insects from the individual nature conservation areas. The insects in the conservation areas were exposed to 16 pesticides on average, ranging from 7 to 27 substances.

Spatial analysis shows origin of pesticides

But where do the pesticides come from? To answer this question, the results on pesticide exposure were combined with a spatial analysis by the IOER. Using the Digital Land Cover Model (LBM-DE), the IOER team determined which arable land, fruit orchards, and vineyards where pesticides are used are in the immediate vicinity or even within the protected areas. The radius of investigation was extended step by step from 500 to 3,500 metres. The proportions of arable land, orchards and vineyards were included in a correlation analysis with the pesticide data. The result of the analysis: the insects took up the pesticides on the cultivated area within a radius of two kilometres. Nature conservation areas in Germany are generally small. On average, they have a size of less than 300 hectares, 60 percent are even smaller than 50 hectares. However, very many insects have a large flight radius.

For the DINA team, these research findings result in new requirements for protected zones. For example, buffer zones, which are managed ecologically and without the use of synthetic pesticides, would have to be established around nature conservation ares and also around protected areas from the European Natura2000 programme. The study shows that buffer zones two kilometres wide would be appropriate in view of the flight radius of the insects. Landscape planning should implement risk management in these areas and prioritise organic farming there, the researchers recommend.

Original publication

Brühl, Carsten A.; Bakanov, Nikita; Köthe, Sebastian; Eichler, Lisa; Sorg, Martin; Hörren, Thomas; Mühlethaler, Roland; Meinel, Gotthard; Lehmann, Gerlind U. C.: Direct pesticide exposure of insects in nature conservation areas in Germany. In: Scientific Reports 11 (2021): 24144.

Website of the DINA project

Contact to the co-authors at the IOER

Dr.-Ing. Gotthard Meinel, e-mail:
Lisa Eichler, e-mail:


The Leibniz Institute of Ecological Urban and Regional Development is jointly funded by the federal government and the federal states.

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