Evaluating 3 species of mason bees for berry crop pollination

We rely heavily on managed honey bees for agricultural pollination, even as concerns about honey bee health and sustainability increase. Research demonstrates that other bee species can pollinate crops effectively, but more work is needed to develop the best strategies for managing them in agriculture.

Mason bees of the genus Osmia are ideal for management as they nest in man-made structures with paper straws, reeds, and drilled wood. These nests have been deployed on farms successfully, most notably with Osmia lignaria in almond orchards, which have been managed since the 1970s. However, best management practices for O. lignaria and newer Osmia pollinators remain understudied. Gaps that are critical to advancing mason bee management include: species-specific nesting material preferences, inclination towards crop specialization or generalism to various flora, and health effects of artificially altering emergence to synchronize with crop blooms.

We looked at brood pollen to determine the fidelity of 3 Osmia species to berry crops, placing Osmia lignaria, bruneri, and ribifloris in blueberry, strawberry, and currant fields in Utah. Next, we examined nesting material choices, determining which resulted in the highest nesting rates. Finally, we tested varying overwintering regimes using 2023’s O. bruneri, to understand the effects of emerging them to coincide with early blooming berry crops.

Our initial results indicate pollination of currants by O. bruneri, and blueberries by O. ribifloris. However, nesting was low. We must continue working on increasing nesting and maintaining bee health while allowing for adaptable emergence timing to best serve various crops.