Wildlife-friendly interventions promote wild bees, but crop species respond differently to the number of visits by pollinators

Modern agricultural systems have negative impacts on pollinators, thereby contributing to their decline. Nature-inclusive farming aims at supporting biodiversity, e.g. by implementing wildlife-friendly interventions. If effective for pollinators, these interventions may also increase pollination success and thereby insect-pollinated crop yields. This study investigates (i) whether wildlife-friendly interventions are effective in supporting wild bees in general, and (ii) crop field-visiting bee species in particular, and (iii) whether increases in flower visits by pollinators (bumblebees, honeybees, hoverflies, solitary bees) increase seed weight in five mass-flowering crops. We performed transect surveys in 2022, 2023, and 2024 on five habitats (three wildlife-friendly interventions and two conventionally managed) in a nature-inclusive farming area in Western Netherlands. Additionally, a field experiment with five flower visitation treatments (netted control, one, two and three visits, open control) was performed in 2024 on oilseed rape, cup plant, camelina, common bean, and flax. Our results show that wildlife-friendly interventions have higher bee abundance and richness, and an increased abundance of crop-visiting species compared to control habitats. The effect of flower visitation rate by pollinators on seed weight per pod differed between crop species. Oilseed rape and cup plant had a saturating relationship between flower visits and seed weight. In contrast, camelina and common bean showed lower seed weight when the flowers were visited by one, two or three pollinators compared to both netted and open control. These findings highlight the benefits of wildlife-friendly interventions on wild bees, including crop-visiting species, and reveal dissimilar responses among crop species to pollinator visits. Our results show that implementation of wildlife-friendly interventions creates conditions favourable to wild bees, emphasizing the importance of conservation policies that incentivize sustainable agricultural practices. Additionally, given the demonstrated link between pollinator visitation and seed production of some crop species, protecting and enhancing pollinators is important to safeguard both ecosystem functioning and agricultural productivity.