Supplementing small farms with native mason bees increases strawberry size and growth rate

Pollination services, especially those of bees, play a vital role in agriculture. Declining honeybee populations require us to find alternative solutions for sustainable agriculture. Native bees are proving to be efficient pollinators. Mason bees (Osmia lignaria) provide valuable pollinator services for some woody orchard species, but their value as pollinators for herbaceous crops is largely untested. We assessed the effectiveness of O. lignaria supplementation on nine strawberry farms over two growing seasons. We specifically selected mason bees for this work because they emerge from cocoons in the springtime, when few other bees are available for pollination. Cocoons are easily deployed on farms and emerged bees have a small flight radius, so they remain localized. We placed cocoons on one side of each berry farm plot (our mason bee addition treatment) but not on the opposite side (our control). We tagged and monitored berries on nine farms throughout the growing season. We performe...