Mass‐flowering crops dilute pollinator abundance in agricultural landscapes across Europe

Mass-flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi-natural habitats (SNHs). Across six European regions and 2 years, we assessed how landscape-scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator-dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator-supporting practices in agricultural landscapes.
The study was funded by the EU FP7 project “Status and Trends of European Pollinators” (244 090, www.STEP-project.net) and Biodiversa‐FACCE project “Enhancing biodiversity‐based ecosystem services to crops through optimised densities of green infrastructure in agricultural landscapes” (PCIN‐2014‐048, http://www.cec.lu.se/research/ecodeal). JPGV and MV acknowledge support from the Severo Ochoa Program for Centres of Excellence in R+D+I (SEV‐2012‐0262), and FLORMAS (CGL 2012‐33801). JBW, VJW, SGP and SPMR acknowledge the support of Insect Pollinators Initiative research funded jointly by a grant from BBSRC, Defra, NERC, the Scottish Government and the Wellcome Trust, under the Living with Environmental Change Partnership. HGS and RB were supported by the Swedish Research Council FORMAS. JS and DK were supported by the Dutch Ministry of Economic Affairs (BO‐11‐011.01‐011 and KB‐14‐003‐006), AH and ISD were supported by the DFG Collaborative Research Centre 1047 Insect timing, and ISD and MD through the 2013–2014 BiodivERsA/FACCE – JPI project Ecodeal with national funding from BMBF.