A sequence- and lab-based approach to investigate chalkbrood disease infection across the western range of blue orchard bees (Osmia lignaria)

Pathogen infection is a significant contributor to mortality and decreased fitness in many bees. Though much research has been done to understand diseases in commercially managed social bee species, much less has been done to understand infection in solitary bees. In particular, there has been concern for spillover of diseases from managed bee species to wild bee species, which could lead to further population declines of our native bees. As a result, it is critical to understand the variation in pathogen strains that can infect solitary bees and if pathogen strains can jump between bee host-species. In this study, we use a multi-method approach to investigate: 1) the variation in chalkbrood strains present within deceased blue orchard bee larvae across their western range and 2) how variable communities of chalkbrood impact infection in blue orchard bees. It is currently unknown how chalkbrood strains vary within blue orchard bees and more broadly across bee species, as well as which strains are infective in blue orchard bees. Therefore, this project will have a significant positive contribution to our broader understanding of bee disease dynamics.