To spray or not to spray...
When pesticides are applied to protect crops, they often take out nature’s pest control agents too. Ever wondered what’s lost—and what you might be ingesting—when fields are sprayed to keep food “safe”? Beyond residues on your plate, pesticide use disrupts delicate predator-prey relationships that naturally regulate pests like aphids. The Urban Plant Ecophysiology Group (Christian Ulrichs) examined how reducing synthetic pesticide use, alongside optimizing nitrogen fertilization, influences aphid populations and their natural antagonists in wheat fields. By comparing organic, conventional, and a novel hybrid cropping system in Brandenburg, Germany, they explored how different management intensities shape insect dynamics and ecosystem health. The results suggest that farming with fewer chemicals not only supports biodiversity—it may leave a lighter ecological footprint on your fork as well. Find out more in their Landbauforschung – Journal of Sustainable and Organic Agriculture Article!
Abstract
Sustainable management practices are needed to reduce adverse impacts of agriculture on biodiversity and ecosystem services. The aim of this study was to examine the effects of avoiding chemical synthetic pesticides with simultaneous nitrogen optimization on predator-prey dynamics of aphids (Aphidoidea) and their antagonists as well as antagonist diversity in wheat cropping systems of different management intensities (organic, conventional, and hybrid (no chemical synthetic pesticides with optimized use of nitrogen fertilizers)) in Brandenburg, Germany. Each cropping system was established with four replicated plots of 50m² each. To assess the impact of management practices, sweep netting of aphids and visual counting of aphids and their antagonists, converted into predator units, were conducted over the course of two years (2022 and 2023). Under the organic treatment, aphids and their antagonists exhibited higher abundances than in the other two cropping systems. The new hybrid cropping system was intermediate between organic and conventional systems, exhibiting higher populations of aphids and their natural predators compared to the conventional system. The application of chemical synthetic pesticides negatively impacted both aphid and predator populations directly and indirectly. Aphids were reduced by insecticides while predators suffered from a lack of food resources or were also affected by insecticides as non-target organisms. Even though aphid abundance benefited from the reduction of chemical synthetic insecticides, a favorable development of aphid antagonists was observed in 2023. Notably, the avoidance of pesticides and the nitrogen optimization contributed to the increase of the number of individuals of aphid antagonists. Achieving a balance without the use of pesticides mitigates environmental damage and reduces the risk of pests developing resistance.