title: Localized deer absence leads to tick amplification.
abstract: Deer support high tick intensities, perpetuating tick populations, but they do not support tick-borne pathogen transmission, so are dilution hosts. We test the hypothesis that absence of deer (loss of a dilution host) will result in either an increase or a reduction in tick density, and that the outcome is scale dependent. We use a complementary methodological approach starting with meta-analysis, followed up by a field experiment. Meta-analysis indicated that larger deer exclosures reduce questing (host-seeking) tick density, but as the exclosure becomes smaller (<2.5 ha) the questing tick density is increased (amplified). To determine the consequences for tick-borne pathogen transmission we carried out a field experiment, comparing the intensity of ticks that fed on hosts competent for tickborne pathogen transmission (rodents) in two small (<1 ha) deer exclosures and their replicated controls. Intensity of larval ticks on rodents was not significantly different between treatments, but nymph intensity, the tick stage responsible for tick-borne encephalitis (TBE) transmission, was higher in deer exclosures. TBE seropositive rodents were found in a deer exclosure but not in the controls. We propose that localized absence of deer (loss of a dilution host) increases tick feeding on rodents, leading to the potential for tick-borne disease hotspots.
authors.affiliation: Center for Infectious Disease Dynamics, 208 Mueller Laboratory, Pennsylvania State University, Pennsylvania 16802, USA. sep18@psu.edu
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Perkins
authors.forename: Isabella M
authors.initials: IM
authors.lastname: Cattadori
authors.forename: Valentina
authors.initials: V
authors.lastname: Tagliapietra
authors.forename: Annapaola P
authors.initials: AP
authors.lastname: Rizzoli
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hudson
mesh_terms: D000818:Animals; D003411:Arvicolinae / Q000469:parasitology*; D003670:Deer; D004675:Encephalitis, Tick-Borne / Q000453:epidemiology / Q000276:immunology; D005260:Female; D018884:Ixodes / Q000502:physiology*; D051189:Murinae / Q000469:parasitology*; D011156:Population Density; D013983:Tick Control / Q000379:methods