Decreasing the size of farm fields and creating more borders between them helps wild pollinators to flourish, whereas increasing crop diversity does not.
Annika Hass at the University of Göttingen in Germany and her colleagues surveyed the number of bees and hoverflies — flies that eat nectar and pollen — in 229 fields across 4 European countries. The team found that wild bees became more abundant as field size shrank and the extent of field borders rose. Borders might help pollinators by providing safe travel routes through fields, the researchers say.
But bee abundance fell as crop diversity rose, the team adds. One possible explanation for that trend: increases in crop diversity might have been driven by the planting of crops that require more fertilizers and herbicides.
The researchers recommend implementing agricultural policies that counteract the trend towards large farm fields.