Tillage in southeastern US row crops reduces ground‐nesting bee incidence and diversity compared to field edges

Abstract Pollination services provided by native bees are vital to the success of flowering plants in agricultural production and natural ecosystems. There are concerns that many native bee species are in decline due to multiple concurrent factors stemming from practices adopted by industrial agricultural production systems, such as the loss of suitable habitat, lack of floral resources and pesticide exposure. Most bee species in North America rear their offspring below ground and are potentially vulnerable to soil management activities, such as tillage operations in row crop settings. We investigated the effects of tillage on ground‐nesting bees in a row crop system by intensively sampling bees nesting within treatments representative of standard tillage practices employed in the Southeastern United States. Our study is among the first to investigate how tillage regimes shape entire bee assemblages in intensively managed US croplands; by contrast, most previous research has focused almost exclusively on the squash bee, Eucera (Peponapis) pruinosa (Say, 1837), and has produced mixed results We found strong evidence that ground‐nesting bee incidence, abundance and diversity declined to varying degrees in all tilled treatments compared to field edges. Clarifying whether tilled fields act as ecological sinks or are simply avoided as unsuitable habitat will be critical for guiding conservation efforts that prioritise the preservation and enhancement of semi‐natural margins in agricultural landscapes.