Details

Autor(en) / Beteiligte

• Yunik, Matthew E.M.
• Diyes, Chulantha P.
• Chilton, Neil B.
• Rich, Stephen

Titel

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

Ist Teil von

• Journal of medical entomology, 2023-11, Vol.60 (6), p.1288-1296

Ort / Verlag

US: Entomological Society of America

Erscheinungsjahr

2023

Link zum Volltext

Quelle

Oxford Journals 2020 Medicine

Beschreibungen/Notizen

• 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.