Geographic distribution and abundance of Dermacentor andersoni and Dermacentor variabilis in Western Canada
Tuesday, November 17, 2015: 8:17 AM
208 C (Convention Center)
Shaun Dergousoff
,
Agriculture And Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, Canada
Neil Chilton
,
Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
Kateryn Rochon
,
Department of Entomology, University of Manitoba, Winnipeg, MB, Canada
Tim Lysyk
,
Agriculture And Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, Canada
Dermacentor andersoni (Rocky Mountain wood tick) and
Dermacentor variabilis (American dog tick) are serious concerns for livestock producers in western Canada. Both species are the primary vectors of
Anaplasma marginale, the causative agent of bovine anaplasmosis.
D. andersoni also causes paralysis in humans and livestock within a restricted portion of its range. Key demographic information required for assessing the risks associated with both species of tick is missing or severely outdated. Therefore, we are using a standardized drag sampling method to estimate the geographic distribution and density of host-seeking adult
D. andersoni and
D. variabilis throughout the four western Canadian provinces.
The results from two years of sampling suggest that the current geographic distribution of D. andersoni is consistent with historical records published between 1940 and 1970. However, the geographic range of D. variabilis has undergone significant northward and westward expansion over the last 50 years. This has produced an area of overlap with the distribution of D. andersoni and there are a number of localities where these two species are now sympatric. In general, the density of questing adult D. variabilis is greater than that of D. andersoni and the density of both species varies significantly between years. Thus, the risk of tick encounters for humans and livestock varies greatly between tick species, sampling year, and geographic locality.
