Agrichemical Surfactant and Pathogen Impacts on the Blue Orchard Bee (<i>Osmia lignaria</i> Say, Hymenoptera: Megachilidae)

Pathogens that infect commercially reared bee species, such as honey bees and bumble bees, have been extensively studied within the last several years, and studies that explore pathogen impacts on solitary bee health are significantly fewer. Consistent pesticide exposure methods are limited to honey bees and do not outline exposure routes to solitary bees, including how to test chemical impacts on immature stages. My research investigated blue orchard bee survival, development, and immune response following pathogen exposure while simultaneously studying organosilicone surfactant (OSS) exposure and possible synergisms between these two stressors. In my first research chapter (Chapter 2), I define methods to test OSS and pathogen oral exposure to the blue orchard bee (Osmia lignaria) in a laboratory setting. In Chapter 3, I investigated blue orchard bee development, survival, and immune responses following RNA virus exposure while studying OSS exposure and possible synergisms between these two stressors. Chapter 4 briefly discusses pathogens found in wild blue orchard bee populations and a dosage experiment to investigate how a pathogen inoculate, a filtrate from diseased honey bees, impacts blue orchard bees. In the second study year of Chapter 4, I added an OSS exposure group to evaluate how Apis mellifera filamentous virus (AmFV), a DNA virus, and its combination with OSS impact the development, survival, and immune response to laboratory-reared blue orchard bees. I document the first detection of AmFV in wild blue orchard bees and quantify relative amounts of AmFV from feeding assay and wild-caught bees. In my final research chapter (Chapter 5), I summarize a cautionary narrative from my research experience and define a critical time point in bee development for bee managers that propagate and sell solitary bees for pollination events. My dissertation develops reliable methods to test the impacts of pathogens, agrichemicals, and their interactions starting at the larval stage using an increasingly managed solitary bee. Additionally, I document the first detection of a DNA virus in wild and managed blue orchard bee populations. This finding highlights the urgent need to prevent any potential spread to bee populations during pollination events.