Mémoire
| Résumé : | Pesticides are a significant threat to pollinators, which play a crucial role in maintaining biodiversity and ecosystem services. Although Brussels has been officially pesticide-free in public spaces since 2019, this study evaluates the effectiveness of this policy by analysing pesticide residues in pollen collected by Osmia cornuta and Osmia bicornis across various urban green spaces. The studied sites include cemeteries, urban parks, nature reserves, and urban agricultural areas. The study revisits ten of the sites previously assessed in 2018 by Vanhemelen to evaluate changes over time and determine whether specific green space types offer better protection against pesticide contamination. Pollen samples were analysed for pesticide residues and floral composition, revealing the presence of nine pesticidal active substances (PAS), with significant contamination levels identified in certain sites, particularly cemeteries. The findings indicate that the degree of urbanisation did not significantly influence the number of detected PAS or the diversity of plant genera in the pollen. Additionally, comparisons with the 2018 data demonstrate changes in contamination levels, highlighting the need for continued monitoring to safeguard pollinators in urban environments. |
