Recommendations for effective insect conservation in nature protected areas based on a transdisciplinary project in Germany

Abstract

The decline of insect abundance and richness has been documented for decades and has received increased attention in recent years. In 2017, a study by Hallmann and colleagues on insect biomasses in German nature protected areas received a great deal of attention and provided the impetus for the creation of the project Diversity of Insects in Nature protected Areas (DINA). The aim of DINA was to investigate possible causes for the decline of insects in nature protected areas throughout Germany and to develop strategies for managing the problem.A major issue for the protection of insects is the lack of insect-specific regulations for nature protected areas and the lack of a risk assessment and verification of the measures applied. Most nature protected areas border on or enclose agricultural land and are structured in a mosaic, resulting in an abundance of small and narrow areas. This leads to fragmentation or even loss of endangered habitats and thus threaten biodiversity. In addition, the impact of agricultural practices, especially pesticides and fertilisers, leads to the degradation of biodiversity at the boundaries of nature protected areas, reducing their effective size. All affected stakeholders need to be involved in solving these threats by working on joint solutions. Furthermore, agriculture in and around nature protected areas must act to promote biodiversity and utilise and develop methods that reverse the current trend. This also requires subsidies from the state to ensure economic sustainability and promote biodiversity-promoting practices.

No recovery in the biomass of flying insects over the last decade in German nature protected areas

“…Since then, several studies provided evidence that insect biomass decline involves a loss in diversity (Hallmann, Ssymank, Sorg, de Kroon, & Jongejans, 2021 ; Hallmann, Ssymank, Sorg, Kroon, & Jongejans, 2021 ; Hausmann et al., 2022 ). In addition, habitat fragmentation is a major driver of insect decline and its negative impact on insect populations is a major problem in many regions (Köthe, Bakanov, Brühl, Eichler, et al., 2023 ; Köthe, Bakanov, Brühl, Gemeinholzer, et al., 2023 ; Köthe, Schneider, Bakanov, Brühl, et al., 2023 ; Tscharntke et al., 2002 ; Tscharntke & Brandl, 2004 ). Due to their species richness, their biomass and their diverse specialisations, insects play a key role in almost all ecosystems.…”

“…DINA is a comprehensive interdisciplinary research project involving eight institutions (Lehmann et al., 2021 ), investigating insect communities and the influence of arable farming on them in 21 NPA in Germany. All selected NPAs are directly adjacent to farmland and part of SACs within the European Natura 2000 network (Brühl et al., 2021 ; Eichler et al., 2022 ; Köthe, Bakanov, Brühl, Eichler, et al., 2023 ; Lehmann et al., 2021 ; Swenson et al., 2022 ). Based on the original model to study the main drivers for the decline in insect biomass (Hallmann et al., 2017 ), we focused on already identified covariates: the influence of arable land and the chemical inputs such as nitrogen and pesticides associated with intensive land use.…”

“…In contrast to Hallmann et al. ( 2017 ), which was an analysis covering only a geographically limited region in Germany, our study was comprehensively conducted at comparable sites (NPA) across Germany covering most biogeographical regions and investigating different scientific questions, such as landscape elements and their spatial distribution pattern (Eichler et al., 2022 ), the diversity of plant communities (Köthe, Bakanov, Brühl, Gemeinholzer, et al., 2023 ; Swenson et al., 2022 ), pesticide residues (Brühl et al., 2021 ) and insect biomass along gradients from arable land into protected habitats through transects (Brühl et al., 2021 ; Köthe, Bakanov, Brühl, Eichler, et al., 2023 ). In addition, this natural science approach is accompanied by co‐development with local stakeholders of solutions for improved insect protection (Fickel et al., 2020 ; Köthe, Bakanov, Brühl, Eichler, et al., 2023 ; Lehmann et al., 2021 ).…”