Bees are the most important pollinators in agricultural systems, with honey bees (Apis mellifera L.) in particular providing the majority of pollination services on commercial farms. However, due to interacting stressors including lack of nutrition and disease, honey bees and other bee species are experiencing elevated loss rates compared to historical records. Access to abundant, high quality, continuous nutrition in the landscape has been suggested as a means of promoting bee health. To test this, I studied honey bee and bumble bee colonies in 12 apiaries that ranged in land cover composition of the surrounding forage landscape. Honey bee colony cluster size and brood area at the end of the summer were most closely related to post-spring pollination colony size and other colony-level variation, whereas bumble bee colony weight, gyne and drone production were related to surrounding land covers. This demonstrates the importance of accounting for potentially confounding honey bee colony variation in landscape-scale studies. To determine if diversity of land covers affected honey bee pollen foraging and colony size, I also measured honey bee colony size and incoming pollen at 12 apiaries located within landscapes of differing land cover diversity, and found that the relationship between land cover diversity, incoming pollen quantity and colony cluster size changed over time. This suggests that land cover diversity alone is insufficient for predicting patterns in honey bee landscape nutrition studies in this region. Conservation Reserve Program (CRP) land may include flowering, herbaceous species in seed mixes, but in states such as Michigan with abundant forage in unmanaged habitats, it is unclear if CRP investments have unique floral composition, and foraging by honey bees and wild bees. I assessed floral composition and bee visitation on CRP land as compared to analogous unmanaged fields and roadside ditches in 31 triplicate sites. Floral abundance, species richness, native flower abundance, and inflorescence coverage were all higher on CRP land, as were honey bee and wild bee visitation, indicating that herbaceous CRP promotes bee foraging through unique floral composition, namely floral density. By assessing the quantity and quality of incoming pollen at apiaries while concurrently surveying floral communities in nearby grassy-herbaceous forage habitat, I found that crude protein in collected pollen decreased throughout the summer, concurrent with decreasing floral richness and abundance. This suggests pollinator plantings should include protein-rich, late-blooming species in their seed mixes. Because nutrition is closely tied to disease in honey bees, supplementing protein may promote recovery from diseases such as European foulbrood. To compare different approaches to managing this disease, European foulbrood-infected colonies were treated with traditional antibiotics, antibiotics with a soy-based protein supplements, soy-based supplement alone, pollen-based supplement, probiotics, or left untreated. There was no significant difference among non-antibiotic treatments in post-treatment recovery speed or nurse bee physiology, suggesting these supplemental feeding treatments and probiotics provide no treatment benefits for European foulbrood. Based on this research, accounting for colony-level variation is essential in honey bee landscape studies. Adding pollinator conservation habitat with an increased emphasis on late-season, protein-rich pollen species in seed mixes can benefit honey bees and wild bee species. This work provides new insights into the effects of landscapes on honey bee and wild bee foraging, nutrition and health by examining different aspects of these indirect relationships.
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