Goff Morgane Le, Dussault Christian, Richard Julien H, Côté Steeve D
Département de biologie and Centre d'études nordiques, Université Laval, 1045 avenue de la Médecine, Québec, (Québec), G1V 0A6, Canada.
Direction de la gestion des espèces et des habitats terrestres, Ministère de l'Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs, 880 chemin Sainte-Foy, 2e étage, Québec, (Québec), G1S 4 × 4, Canada.
Ticks Tick Borne Dis. 2025 Jul;16(4):102519. doi: 10.1016/j.ttbdis.2025.102519. Epub 2025 Jul 9.
Ticks are responsible for large economic losses because of their impact on livestock and wildlife. In recent years, winter ticks (Dermacentor albipictus) have caused mass mortalities in moose (alces) populations of North America, leading to host mortality due to severe blood loss. During their off-host stages (i.e. egg and larvae), winter ticks are particularly vulnerable to mortality because of potential exposure to stressful abiotic conditions that could dehydrate eggs or freeze larvae. We conducted a field experiment in Québec, Canada, to better understand larval questing behaviour and assess the ability of unfed larvae to survive over the winter to the following fall. In the laboratory, we tested the tolerance of eggs to different saturation deficits reflected by combinations of temperature and humidity and evaluated the tolerance of larvae to sub-freezing temperatures. We found that unfed winter tick larvae did not survive until a second fall regardless of habitat types (open, closed or sheltered from the snow) and thus could not quest for a host for two consecutive years. However, unfed larvae withstood short-term exposure to low sub-freezing temperatures, potentially prolonging their questing period and increasing the likelihood of moose infestations. Egg survival varied among saturation deficits, but survival tended to be higher at 30 °C and lower at 22 °C regardless of the saturation deficit. Overall, we found that the free stages of winter ticks are highly tolerant of extreme conditions, reinforcing the concern that winter ticks represent for moose populations.
蜱虫因其对家畜和野生动物的影响而造成巨大经济损失。近年来，冬季蜱虫（白纹革蜱）已导致北美驼鹿种群大量死亡，致使宿主因严重失血而死亡。在其非寄生阶段（即卵和幼虫阶段），冬季蜱虫特别容易死亡，因为它们可能会暴露在有压力的非生物条件下，这些条件可能会使卵脱水或使幼虫冻结。我们在加拿大魁北克进行了一项野外实验，以更好地了解幼虫的寻觅行为，并评估未进食的幼虫越冬至次年秋季的生存能力。在实验室中，我们测试了卵对由温度和湿度组合反映的不同饱和亏缺的耐受性，并评估了幼虫对亚冰点温度的耐受性。我们发现，无论栖息地类型（开阔、封闭或有雪覆盖）如何，未进食的冬季蜱虫幼虫都无法存活到第二个秋季，因此无法连续两年寻觅宿主。然而，未进食的幼虫能够耐受短期暴露于低温亚冰点温度，这可能会延长它们的寻觅期并增加驼鹿被感染的可能性。卵的存活率在不同饱和亏缺之间有所不同，但无论饱和亏缺如何，在30°C时存活率往往较高，在22°C时存活率较低。总体而言，我们发现冬季蜱虫的自由阶段对极端条件具有高度耐受性，这加剧了人们对冬季蜱虫对驼鹿种群构成威胁的担忧。
