Insects in nature reserves are contaminated with a cocktail of pesticides

In this blog post Carsten Brühl explains the background and findings of their paper on pesticide residues measured on insect samples from nature conservation areas in Germany published in Scientific reports.

Over the past three decades, more than 75 percent of the biomass of insects in German nature reserves has demonstrably disappeared. The biodiversity crisis described by the World Biodiversity Council (IPBES) is therefore also taking place in Germany inside protected areas. The fatal thing is that without insects, ecosystems collapse and for example plants are no longer adequately pollinated. Experts agree that pesticides are one of the main causes of the observed insect decline in agricultural landscapes. Now a recent study with the participation of the iES (Institute for Environmental Sciences) Landau shows that insects are contaminated with an average of 16 different pesticides even in nature reserves. None of the insect samples of the nature conservation areas examined was unpolluted. Pesticides have not yet been considered in conservation management, risk analyses are lacking, and conventionally farmed areas with synthetic pesticide use are located inside protected areas and surround them.

Background of the study

Under the coordination of the German Nature and Biodiversity Conservation Union (NABU), nine partners in the DINA project (Diversity of Insects in Nature protected Areas) have recorded and documented insect diversity in nature reserves over a period of two years. The project is financed by the German Federal Ministry of Education and Research. The Entomological Society Krefeld, a collaboration partner in the DINA project, documented the decline in insect biomass for the first time in a publication in 2017. In 21 representative nature reserves covering different habitats across Germany, the DINA partners recorded insect populations and monitored potential environmental impacts. The study sites in the DINA project are also “strictly protected habitats” in the Natura2000 program of the European Union. All of the studied protected areas are located in the agricultural landscape and are surrounded by conventionally used farmland.

“Our data show that insects in nature reserves are contaminated with a cocktail of pesticides,” emphasizes Carsten Brühl. In the DINA project, he and his team took a close look at the pesticide contamination of mixed insect samples. They used a newly developed analytical method to study for the first time at how much the insects themselves are contaminated. Previous studies, although generally scarce for agricultural landscapes, have provided first data on air and soil contamination. In the DINA project, a standardized protocol was used with series of malaise traps in 21 nature conservation areas in which the collected insects are preserved in alcohol. At the same time, alcohol acts as a solvent for pesticides. This allowed the Landau research team to directly investigate which pesticides the insects were carrying at these study sites. “With our method, 92 pesticides currently approved in Germany can be analyzed simultaneously in small quantities,” explains Nikita Bakanov from the Landau research group. The researchers evaluated data from protected areas in May and August of 2020.

Malaise trap inside a nature conservation area. © Entomologischer Verein Krefeld, Lizenz creative commons 4.0

Insect communities contaminated with up to 27 pesticides

On the insects, the scientists found 47 of the 92 pesticides distributed across the nature conservation areas. On average, they detected 16 different pesticides on insect samples inside the protected areas studied. In one protected area, the load on the animals even consisted of 27 different substances, the minimum load was seven pesticides. “When you consider that risk assessment in the context of pesticide approval procedures assumes that insects come into contact with only one pesticide, it is obvious how unrealistic this assessment practice is,” Carsten Brühl emphasizes. Brühl, who has been studying the effects of pesticides on the terrestrial environment for 20 years, was not surprised by the results. “It’s good that we can now show and prove our assumptions thanks to the new methodology we developed.” The approach builds on a previous project in which the Landau researchers considered the different insect-pesticide contact pathways.

Insect sample of a Malaise trap. The ethanol was used for pesticide analysis. (© Entomologischer Verein Krefeld, Lizenz creative commons 4.0)

Protection zones of two kilometers necessary

The researchers combined the results with a spatial analysis. “We wanted to find out where the insects take up the pesticides,” explains Lisa Eichler from the Leibniz Institute for Ecological and Regional Development in Dresden, another DINA partner. The result of the landscape analysis: the insects came in contact with the pesticides in the agricultural production area within a radius of two kilometres. One must know about this: Nature conservation areas in Germany are generally small (on average around 300 ha but 60% are smaller than 50 ha) while many insects have a large flight radius. “Policymakers, scientists and landscape planners must therefore plan for buffer zones and think in other scales, 10-20 m is not enough,” says Dr. Martin Sorg of the Entomological Society Krefeld. A protected buffer zone around nature reserves and EU Natura2000 conservation areas, where no synthetic pesticides are used and which is managed organically instead, must be established. Landscape planning needs to implement risk management in those two-kilometer-wide buffer zones around nature reserves and prioritize organic farming there, the researchers recommend.

Calculations by the research team also show that if such buffer zones were implemented for all nature conservation areas in the agricultural landscape of Germany, it would affect 30 percent of agricultural land. “This figure may seem large at first glance,” but would be in line with the EU’s aim for 25 percent and the new German government calling for 30 percent of organic agriculture by 2030. “With our study, we are providing recommendations for achieving this transformation goal, for which policymakers still have nine years,” says Brühl.

Targeted research and organic farming in and around protected areas

The new German government has set the 30 percent organic agriculture target by 2030, and the EU additionally aims to halve the use of synthetic pesticides by the same year. “The political goal is there, and it is also supported by consumer demand for organic food. What is important now is targeted implementation,” Brühl emphasizes. “The Commission on the Future of Agriculture in Germany also concluded this August that agriculture has to change.” However, their formulated vision of the future did not specify percentages of organic farming and also omitted the reduction of pesticide use. What is needed now, is to provide farmers with advisory support for the transformation and to locate organic farming where it is most required – as buffer zones around protected areas. “Strictly protected” habitats under EU law would then also be protected from pesticide impacts in reality. Organic agriculture should be used as a tool there – for effective protection and conservation of biodiversity in areas designated for this purpose.

A targeted organic agriculture 2.0 needs to be supported with massive applied research. In parallel, it would be necessary to continuously observe and monitor how insect communities and the use of pesticides are developing within the period of transformation, emphasize the researchers. The monitoring methods established in the DINA project would be particularly suitable for this purpose.

The study

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