Off-host survival of Dermacentor variabilis (Acari: Ixodidae) adults near their northern distributional limit in Saskatchewan, Canada. 2023

Matthew E M Yunik, and Chulantha P Diyes, and Neil B Chilton
Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

Dermacentor variabilis (Say) is expanding its range northwards in Saskatchewan and Manitoba (Canada). Knowledge of the relative ability of different life cycle stages to survive off-host over winter is important for assessing the potential for further range expansion and risk of pathogen transmission. In the present study, the off-host survival of D. variabilis adults was determined in outdoor terraria within a field plot close to Lizard Lake Community Pasture (LLCP) situated near the northern distributional limit in Saskatchewan. Only a small proportion (7%) of adult ticks in this relatively recently established population survived from mid-summer to late winter. Off-host survival had declined further to <4% by mid-spring. A significantly greater proportion of female ticks (6%) survived from mid-summer to mid-spring than did male ticks (1%). The supercooling points (SCPs), the temperature below 0 °C when body fluids spontaneously freeze, of the 17 ticks that survived through to mid-spring did not differ significantly from the SCPs of questing ticks in the previous summer, suggesting adult D. variabilis do not undergo cold hardening during winter diapause. The off-host survival of D. variabilis adults near LLCP was also much lower than that previously reported for adults from Sandy Hook in Manitoba, a population that has been established for decades. This finding suggests that there is geographical variation in the ability of D. variabilis in southern Canada to survive from mid-summer to the subsequent spring. However, the ecological and genetic factors influencing the survival of northern populations of D. variabilis requires further investigation.

UI MeSH Term Description Entries
D008297 Male Males
D008350 Manitoba A province of Canada, lying between the provinces of Saskatchewan and Ontario. Its capital is Winnipeg. Taking its name from Lake Manitoba, itself named for one of its islands, the name derived from Algonquian Manitou, great spirit. (From Webster's New Geographical Dictionary, 1988, p724 & Room, Brewer's Dictionary of Names, 1992, p332)
D003870 Dermacentor A widely distributed genus of TICKS, in the family IXODIDAE, including a number that infest humans and other mammals. Several are vectors of diseases such as TULAREMIA; ROCKY MOUNTAIN SPOTTED FEVER; COLORADO TICK FEVER; and ANAPLASMOSIS. Dermacentor andersoni,Rocky Mountain Wood Tick
D005260 Female Females
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012525 Saskatchewan A province of Canada, lying between the provinces of Alberta and Manitoba. Its capital is Regina. It is entirely a plains region with prairie in the south and wooded country with many lakes and swamps in the north. The name was taken from the Saskatchewan River from the Cree name Kisiskatchewani Sipi, meaning rapid-flowing river. (From Webster's New Geographical Dictionary, 1988, p1083 & Room, Brewer's Dictionary of Names, 1992, p486)
D026863 Ixodidae A family of hardbacked TICKS, in the subclass ACARI. Genera include DERMACENTOR and IXODES among others. Ticks, Hardbacked,Hard Ticks,Hard Tick,Hardbacked Tick,Hardbacked Ticks,Tick, Hard,Tick, Hardbacked,Ticks, Hard

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