Authors: Dániel-Ferreira, Juliana; Berggren, Åsa;Bommarco, Riccardo;Wissman, Jörgen;Öckinger, Erik;

Targeted management of road verges has a great potential to benefit biodiversity, but there is growing concern that road verges can act as ecological traps for pollinators. Roads and road verges also have the potential to influence the movements of flower-visiting insects by acting as barriers or corridors. We selected 10 pairs of road verges differing in the number of flowering plant species (rich vs poor) and a gradient in traffic intensity. Here, we explored the movements of flower-visiting insects by marking flowers with fluorescent dye, and observed the behaviour and mortality risk of bumblebee queens. Road verges were corridors for flower-visiting insects, and roads were barriers to movement independent of traffic intensity. Insects avoided crossing the road more frequently when there was a higher density of flowers in the road verge, indicating that flower-rich road verges could decrease the mortality risk. For bumblebee queens, the mortality risk dramatically increased with increasing traffic independent of the flower density in the road verge. Our study suggests that the role of road verges as barriers and ecological traps for flower-visiting insects depends on their behaviour, and could be modified by adapting the road verge management.