Exposure of Larvae of the Solitary Bee Osmia bicornis to the Honey Bee Pathogen Nosema ceranae Affects Life History
1
Institut für Biologie, Universität Berlin, 14195 Berlin, Germany
2
Abteilung 4 Material und Umwelt, Bundesanstalt für Materialforschung und-prüfung (BAM), 12205 Berlin, Germany
*
Authors to whom correspondence should be addressed.
Insects 2019, 10(11), 380; https://doi.org/10.3390/insects10110380
Received: 30 September 2019 / Revised: 24 October 2019 / Accepted: 28 October 2019 / Published: 31 October 2019
(This article belongs to the Special Issue Insect Immunity and Pathology)
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 Nosema ceranae. While the impacts of N. ceranae in honey bees are well documented, virtually nothing is known about its effects in solitary wild bees. The solitary mason bee Osmia bicornis is a common pollinator in orchards and amenable to commercial management. Here, we experimentally exposed larvae of O. bicornis to food contaminated with N. ceranae 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 O. bicornis infection, our findings indicate that exposure of larvae to viable N. ceranae spores could affect bee development.
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Keywords:
wild bees; Nosema ceranae; Osmia bicornis; pathogen transmission; solitary bees; bee health; bee diseases
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MDPI and ACS Style
Bramke, K.; Müller, U.; McMahon, D.P.; Rolff, J. Exposure of Larvae of the Solitary Bee Osmia bicornis to the Honey Bee Pathogen Nosema ceranae Affects Life History. Insects 2019, 10, 380.
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