| Summary: | Wild bees are important pollinators of wild plants and agricultural crops and they are threatened by several environmental stressors including emerging pathogens. Honey bees have been suggested as a potential source of pathogen spillover. One prevalent pathogen that has recently emerged as a honey bee disease is the microsporidian <i>Nosema ceranae</i>. While the impacts of<i> N. ceranae </i>in honey bees are well documented, virtually nothing is known about its effects in solitary wild bees. The solitary mason bee <i>Osmia bicornis</i> is a common pollinator in orchards and amenable to commercial management. Here, we experimentally exposed larvae of <i>O. bicornis</i> to food contaminated with <i>N. ceranae</i> and document spore presence during larval development. We measured mortality, growth parameters, and timing of pupation in a semi-field experiment. Hatched individuals were assessed for physiological state including fat body mass, wing muscle mass, and body size. We recorded higher mortality in the viable-spore-exposed group but could only detect a low number of spores among the individuals of this treatment. Viable-spore-treated individuals with higher head capsule width had a delayed pupation start. No impact on the physiological status could be detected in hatched imagines. Although we did not find overt evidence of <i>O. bicornis</i> infection, our findings indicate that exposure of larvae to viable <i>N. ceranae</i> spores could affect bee development.
|
|---|