Native vegetation embedded in landscapes dominated by corn and soybean improves honey bee health and productivity.
Abstract
Balancing demand for food while supporting biodiversity and ecosystem services in landscapes committed to crop production may require integrating conservation with agriculture. Adding strips of diverse, native, perennial vegetation, through the recently created prairie strips practice of the U.S. Conservation Reserve Program, into annual cropland reduces soil and nutrient loss, and supports more diverse and abundant communities of birds and insects, including native pollinators. It remains unclear if prairie strips can reverse declines in the health and productivity of the exotic honey bee in the U.S. This study determined if prairie strips provide floral resources to honey bees and support colony vigour, in a highly farmed landscape with limited perennial habitat. We hypothesized that honey bee health and productivity would be improved if given access to prairie strips, and this hypothesis was tested in a multi-year, replicated, longitudinal study on commercial, conventional farms committed to corn and soybean production with and without prairie strips. We predicted that prairie strips would have more diverse flowering plants, and colonies located in these strips would be healthier and more productive than colonies kept at farms without purposefully established native vegetation (i.e. control fields). We found that prairie strips had more diverse flowering plants and abundant floral resources than control fields. Colonies kept at fields with prairie strips collected 50% more pollen during the growing season (June-September), had a 24% larger end-of-season worker bee populations, and 20% higher overwinter survival than colonies kept at control fields. Furthermore, colonies kept at prairie strips were 24% heavier when they reached their peak-weight in August, an indicator of honey production. Honey bees collected pollen from flowering plants found in prairie strips, revealing the potential for interactions with wild pollinators. However, this was limited to 50% of the taxa in prairie strips, suggesting honey bees may not deplete all of the food resources simultaneously used by wild pollinators. Synthesis and applications. Our results suggest that efforts to enhance habitat diversity within croplands with native plants increase honey bee health and productivity while providing multiple additional ecosystem services important to agriculture.