title: So near and yet so far: harmonic radar reveals reduced homing ability of Nosema infected honeybees.
abstract: Pathogens may gain a fitness advantage through manipulation of the behaviour of their hosts. Likewise, host behavioural changes can be a defence mechanism, counteracting the impact of pathogens on host fitness. We apply harmonic radar technology to characterize the impact of an emerging pathogen--Nosema ceranae (Microsporidia)--on honeybee (Apis mellifera) flight and orientation performance in the field. Honeybees are the most important commercial pollinators. Emerging diseases have been proposed to play a prominent role in colony decline, partly through sub-lethal behavioural manipulation of their hosts. We found that homing success was significantly reduced in diseased (65.8%) versus healthy foragers (92.5%). Although lost bees had significantly reduced continuous flight times and prolonged resting times, other flight characteristics and navigational abilities showed no significant difference between infected and non-infected bees. Our results suggest that infected bees express normal flight characteristics but are constrained in their homing ability, potentially compromising the colony by reducing its resource inputs, but also counteracting the intra-colony spread of infection. We provide the first high-resolution analysis of sub-lethal effects of an emerging disease on insect flight behaviour. The potential causes and the implications for both host and parasite are discussed.
authors.affiliation: Department of Agro-Ecology, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom; School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom.
authors.forename: Stephan
authors.initials: S
authors.lastname: Wolf
authors.affiliation: School of Biological Sciences, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom; Institute for Biology, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale, Germany.
authors.forename: Dino P
authors.initials: DP
authors.lastname: McMahon
authors.affiliation: Department of Agro-Ecology, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.
authors.forename: Ka S
authors.initials: KS
authors.lastname: Lim
authors.affiliation: Department of Agro-Ecology, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom; IST Austria (Institute of Science and Technology Austria), Klosterneuburg, Austria.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Pull
authors.affiliation: Department of Computational and Systems Biology, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.
authors.forename: Suzanne J
authors.initials: SJ
authors.lastname: Clark
authors.affiliation: School of Biological Sciences, Queen's University Belfast, Belfast, Northern Ireland, United Kingdom; Institute for Biology, Martin-Luther-Universität Halle-Wittenberg, Halle/Saale, Germany.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Paxton
authors.affiliation: Department of Agro-Ecology, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom; Environment and Sustainability Institute, University of Exeter, Falmouth, Cornwall, United Kingdom.
authors.forename: Juliet L
authors.initials: JL
authors.lastname: Osborne
mesh_terms: D000818:Animals; D001516:Bees / Q000382:microbiology*; D006702:Homing Behavior; D054884:Host-Pathogen Interactions / Q000502:physiology*; D016881:Microsporidiosis / Q000503:physiopathology*; D016818:Nosema
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