title: Food provisioning alters infection dynamics in populations of a wild rodent.
abstract: While pathogens are often assumed to limit the growth of wildlife populations, experimental evidence for their effects is rare. A lack of food resources has been suggested to enhance the negative effects of pathogen infection on host populations, but this theory has received little investigation. We conducted a replicated two-factor enclosure experiment, with introduction of the bacterium Bordetella bronchiseptica and food supplementation, to evaluate the individual and interactive effects of pathogen infection and food availability on vole populations during a boreal winter. We show that prior to bacteria introduction, vole populations were limited by food availability. Bordetella bronchiseptica introduction then reduced population growth and abundance, but contrary to predictions, primarily in food supplemented populations. Infection prevalence and pathological changes in vole lungs were most common in food supplemented populations, and are likely to have resulted from increased congregation and bacteria transmission around feeding stations. Bordetella bronchiseptica-infected lungs often showed protozoan co-infection (consistent with Hepatozoon erhardovae), together with more severe inflammatory changes. Using a multidisciplinary approach, this study demonstrates a complex picture of interactions and underlying mechanisms, leading to population-level effects. Our results highlight the potential for food provisioning to markedly influence disease processes in wildlife mammal populations.
authors.affiliation: Natural Resources Institute Finland, Suonenjoki, Finland Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland kristian.forbes@helsinki.fi.
authors.forename: Kristian M
authors.initials: KM
authors.lastname: Forbes
authors.affiliation: Natural Resources Institute Finland, Vantaa, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Henttonen
authors.affiliation: Production Animal and Wildlife Health Research Unit, Finnish Food Safety Authority Evira, Oulu, Finland.
authors.forename: Varpu
authors.initials: V
authors.lastname: Hirvelä-Koski
authors.affiliation: Department of Veterinary Biosciences, University of Helsinki, Helsinki, Finland Department of Infection Biology, Institute of Global Health, University of Liverpool, Liverpool, UK.
authors.forename: Anja
authors.initials: A
authors.lastname: Kipar
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland.
authors.forename: Tapio
authors.initials: T
authors.lastname: Mappes
authors.affiliation: Natural Resources Institute Finland, Suonenjoki, Finland Department of Botany and Zoology, Masaryk University, Brno, Czech Republic.
authors.forename: Peter
authors.initials: P
authors.lastname: Stuart
authors.affiliation: Natural Resources Institute Finland, Suonenjoki, Finland.
authors.forename: Otso
authors.initials: O
authors.lastname: Huitu
mesh_terms: D000818:Animals; D003411:Arvicolinae; D001885:Bordetella Infections / Q000382:microbiology / Q000662:veterinary*; D016950:Bordetella bronchiseptica / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements / Q000032:analysis*; D005260:Female; D005387:Finland; D008297:Male; D011157:Population Dynamics; D011158:Population Growth; D011897:Random Allocation; D012376:Rodent Diseases / Q000382:microbiology*; D012621:Seasons
keywords: Bordetella bronchiseptica; co-infection; factorial experiment; food supplementation; population limitation; vole