Insect diversity is also decreasing in Germany – even in nature reserves. In the DINA project, scientists from eight research institutions spent four years investigating the causes of this and what can be done to counteract the continuing decline in insects. They have now presented their results and are giving recommendations for action to protect the native insect world. The influence of agriculture and its pesticides far into the nature reserves plays an important role in this.
In 2017, a long-term study of the state of native insect populations caused a stir and concern. Because it showed that the biomass of flying insects fell by 76 percent between 1989 and 2016 – and this in nature reserves. Two years later, a complementary study of arthropod biomass, abundance and species number in grassland and forests confirmed this trend for insects and arthropods as a whole. “There was great dismay when the extent of the dramatic decline in insect diversity became public six years ago,” says Gerlind Lehmann, DINA project manager at NABU.
Agriculture and especially pesticides
But what are the reasons for the decline in insects? This was not clear from the data in the original study. However, the location of the sample sites near intensively used agricultural land suggested that habitat loss, food loss and pesticide use could play a role. In order to create more clarity, the transdisciplinary research project “DINA – Diversity of insects in nature conservation areas” was initiated in 2019. Under the direction of the NABU – Naturschutzbund Deutschland, scientists from eight environmental and biodiversity research institutions researched where the problems for the insects lie and what possible solutions could look like.
Key results of the research project were presented today. The investigations showed that insects travel longer distances than previously thought when searching for food and that they frequently seek out crops as a source of food. As a result, even the insects in nature reserves are often out and about in the surrounding fields – and are exposed to pesticides there. “Pesticides are detected on insects in all of the protected areas examined, with insects being contaminated in the agricultural landscape within a radius of 2000 meters,” the scientists report. Several pesticides were often detected simultaneously in the insects examined, and their exposure also increased in areas used intensively for agriculture. “Adjacent, conventionally farmed arable land also has a negative effect on the occurrence of endangered plant species in neighboring, protected habitats,” reports Thomas Hörren from the Entomological Association Krefeld eV (EVK).
What can be done against insect decline?
The results of the DINA project also provide important approaches for solving the problem. “Effective insect protection must include not only the areas in the area, but also in the immediate vicinity in the development of protective measures,” says Florian Dirk Schneider from the ISOE – Institute for Social-Ecological Research. “Accepted and practical solutions to this challenge therefore require cooperation between agriculture, nature conservation, science, authorities, politics and civil society. In order for a trend reversal for better insect protection to be possible, it is important to use the willingness to cooperate that exists among many local stakeholders around a nature reserve and to promote commitment to insect protection.”
The research consortium proposes three key actions to effectively protect insect diversity:
1. Prioritize biodiversity in setting goals and planning for protected areas: To ensure that biological diversity in the designated areas is actually protected, the surrounding agricultural land should be included – for example when strategies are developed and measures are planned. It must be taken into account that edge effects and environmental influences affect the protected areas within a radius of up to two kilometers.
2. Enable nationwide monitoring and site-specific risk analysis: In order to be able to better assess the risks for insect populations, more data must be collected through monitoring and pesticide analysis. Areas that are particularly worthy of protection should be prioritized. “In the perception of many of those involved, a specific threat to insects in their own protected area cannot yet be unequivocally derived from the available data. The nature conservation authorities and farms can therefore only partially justify preventive measures to protect the insects,” explains Schneider.
3. Encourage the participation of all relevant actors: In order for protective measures to be implemented effectively at the local level, all stakeholders from landscape conservation, agriculture, nature conservation, politics and civil society must be involved. “Dialogue formats offer the opportunity to compare knowledge, mutual understanding of obstacles and interests and open up paths to solutions that are practical and capable of consensus,” says Schneider. In addition, biodiversity should be established as an important part of education for sustainable development.
Source: ISOE – Institute for Social-Ecological Research; DIN Policy Brief – Central results and recommendations of the research association