title: The influence of abiotic and biotic factors on the invasion of Ixodes scapularis in Ontario, Canada.
abstract: In northeastern North America, the blacklegged tick, Ixodes scapularis, is the vector of numerous tick-borne pathogens, including the agent of Lyme disease, Borrelia burgdorferi sensu stricto. Since 1990, there has been a rapid spread of I. scapularis northward into the province of Ontario, Canada. Climate change has been implicated as one of the driving factors for the spread of this vector. Other ecological factors also influence survival of I. scapularis populations and may facilitate invasion. The objective of this study was to identify local abiotic and biotic factors of significance for the invasion of I. scapularis in Ontario. The presence of ticks was determined by drag sampling at 154 sites in southern, eastern and central Ontario from May to October in 2014 and 2015. At each site, data on site aspect, forest cover, understory density and composition, soil moisture and composition, and the depth of litter layer were collected. Cumulative degree days above zero °C, total precipitation and elevation were attributed to each site using a geographic information system. A mixed multi-variable logistic regression model was created to assess the impact of the ecological factors on the presence of I. scapularis. In total, I. scapularis was found at 29 sites (18.8%) across the study area. The density of the understory, the presence of shrubs and the interaction of these two ecological factors were statistically significant, as well as longitude and cumulative degree days above zero. Our findings illustrate that local ecological factors are of importance for the invasion of I. scapularis into Ontario, and may be used to enhance local public health interventions and current predictive models and risk maps for I. scapularis.
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada. Electronic address: kclow@uoguelph.ca.
authors.forename: Katie M
authors.initials: KM
authors.lastname: Clow
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada, 3200 Sicotte, C.P. 5000, Saint-Hyacinthe, Quebec, J2S 7C6, Canada. Electronic address: Nicholas.Ogden@phac-aspc.gc.ca.
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Ogden
authors.affiliation: National Microbiology Laboratory, Public Health Agency of Canada,1015 Arlington Street, Winnipeg R3E 3R2, Canada. Electronic address: Robbin.Lindsay@phac-aspc.gc.ca.
authors.forename: L Robbin
authors.initials: LR
authors.lastname: Lindsay
authors.affiliation: Office of the Chief Science Officer, Public Health Agency of Canada,130 Colonnade Road, Ottawa, Ontario K1A 0K9, Canada. Electronic address: Pascal.Michel@phac-aspc.gc.ca.
authors.forename: Pascal
authors.initials: P
authors.lastname: Michel
authors.affiliation: Department of Population Medicine, Ontario Veterinary College, University of Guelph,50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada. Electronic address: dpearl@uoguelph.ca.
authors.forename: David L
authors.initials: DL
authors.lastname: Pearl
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada; Canadian Wildlife Health Cooperative, Ontario Veterinary College, University of Guelph,50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada. Electronic address: cjardi01@uoguelph.ca.
authors.forename: Claire M
authors.initials: CM
authors.lastname: Jardine
mesh_terms: D063147:Animal Distribution; D000818:Animals; D057231:Climate Change; D018884:Ixodes / Q000254:growth & development / Q000502:physiology*; D007814:Larva / Q000502:physiology; D009758:Nymph / Q000502:physiology; D009864:Ontario
keywords: Borrelia burgdorferi sensu stricto; Disease ecology; Emergence; Ixodes scapularis; Lyme disease; Vector-borne