Wildflower strips enhance wild bee reproductive success

1. Intensification of agriculture has resulted in a simplification and fragmentation of agroecosystems. Yet, its impact on the reproductive success and population dynamics of wild bees, and how adverse effects can be mitigated, remains poorly understood.

2. We established populations of seven solitary bee species varying in body size in experimentally sown wild flower strips (WFS), existing semi-natural habitats (SNH; forest edges) and isolated sites lacking WFS and SNH in the local surrounding (350 m radius) to test whether (i) the wild bee species use planted flowers of wildflower strips (WFS) to provision offspring with pollen, (ii) whether vicinity to WFS reduces their foraging trip duration, (iii) parasitism rate, and (iv) increases bee reproductive success of nesting populations. Furthermore, we tested whether the effect size depends on the body size of the bee species considered.

3. We show that wild bees nesting in WFS provisioned their offspring primarily with pollen from...