title: Nosema spp. infections cause no energetic stress in tolerant honeybees.
abstract: Host-pathogen coevolution leads to reciprocal adaptations, allowing pathogens to increase host exploitation or hosts to minimise costs of infection. As pathogen resistance is often associated with considerable costs, tolerance may be an evolutionary alternative. Here, we examined the effect of two closely related and highly host dependent intracellular gut pathogens, Nosema apis and Nosema ceranae, on the energetic state in Nosema tolerant and sensitive honeybees facing the infection. We quantified the three major haemolymph carbohydrates fructose, glucose, and trehalose using high-performance liquid chromatography (HPLC) as a measure for host energetic state. Trehalose levels in the haemolymph were negatively associated with N. apis infection intensity and with N. ceranae infection regardless of the infection intensity in sensitive honeybees. Nevertheless, there was no such association in Nosema spp. infected tolerant honeybees. These findings suggest that energy availability in tolerant honeybees was not compromised by the infection. This result obtained at the individual level may also have implications at the colony level where workers in spite of a Nosema infection can still perform as well as healthy bees, maintaining colony efficiency and productivity.
authors.affiliation: Institute for Biology, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany. christoph.kurze@zoologie.uni-halle.de.
authors.forename: Christoph
authors.initials: C
authors.lastname: Kurze
authors.affiliation: Institute for Biology, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany.
authors.forename: Christopher
authors.initials: C
authors.lastname: Mayack
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin-Luther-Universität Halle-Wittenberg, 06120, Halle (Saale), Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Hirche
authors.affiliation: Institute of Agricultural and Nutritional Sciences, Martin-Luther-Universität Halle-Wittenberg, 06120, Halle (Saale), Germany.
authors.forename: Gabriele I
authors.initials: GI
authors.lastname: Stangl
authors.affiliation: INRA, UR 406 Abeilles et Environnement, 84914, Avignon, Cedex 9, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Le Conte
authors.affiliation: Department of Agroecology Flakkebjerg, Aarhus University, 4200, Slagelse, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Kryger
authors.affiliation: Institute for Biology, Martin-Luther-Universität Halle-Wittenberg, 06099, Halle (Saale), Germany.|German Institute for Integrative Biodiversity Research (iDiv), 04103, Leipzig, Germany.|Department of Zoology and Entomology, University of Pretoria, 0002, Pretoria, South Africa.
authors.forename: Robin F A
authors.initials: RF
authors.lastname: Moritz
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001516:Bees / Q000382:microbiology* / Q000502:physiology; D004734:Energy Metabolism; D006458:Hemolymph; D054884:Host-Pathogen Interactions; D016818:Nosema / Q000502:physiology*; D013312:Stress, Physiological
keywords: Adaptation; Energetic stress; Fitness cost; Host-parasite interaction; Immune response