Effect of honey bees (Apis mellifera) and wild insect pollination on rapeseed (Brassica napus) yield in the Argentine Pampas

Rapeseed (Brassica napus) can benefit from insect pollination to maximize yield. The Argentine Pampas represent one of the most intensively cultivated regions of the world, characterized by landscape homogenization and a reduced availability of natural habitats for wild pollinators. These conditions provide a unique context to explore the contribution of managed and wild pollinators to rapeseed (Brassica napus) yield under highly intensified agricultural systems. The objective of this study was to evaluate the influence of Apis mellifera and wild insect pollinators on quantitative and qualitative components of rapeseed seed yield in fields of the Argentine Pampas, using a caging experiment. Three pollination treatments were applied: open pollination, pollinator exclusion, and A. mellifera-only. Compared to the exclusion treatment, pollination exclusive by A. mellifera increased crop yield by 33%, whereas open pollination resulted in a 20% increase. These differences in total yield were mainly explained by increases in quantitative components, such as number of seeds per fruit and fruits per plant. Seed physiological quality (ripeness, germination power and vigor) followed the same pattern among treatments. Our findings emphasize the importance of adjusting agricultural practices to promote the conservation of wild pollinators in rapeseed crops, and suggest that supplemental pollination with A. mellifera could serve as a useful tool for enhancing crop production under intensive management systems.