Localized deer absence leads to tick amplification.
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.
Perkins
Sarah E
SE
Center for Infectious Disease Dynamics, 208 Mueller Laboratory, Pennsylvania State University, Pennsylvania 16802, USA. sep18@psu.edu
Cattadori
Isabella M
IM
Tagliapietra
Valentina
V
Rizzoli
Annapaola P
AP
Hudson
Peter J
PJ
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