Where and how do ticks overwinter? - briefly
Adult females and nymphs locate insulated microhabitats—leaf litter, rodent burrows, or bark crevices—and enter diapause to survive the cold season, while males generally remain active on hosts or within the litter and eggs are deposited in protected sites to hatch in spring.
Where and how do ticks overwinter? - in detail
Ticks survive the cold season by entering a dormant state known as diapause, which reduces metabolic activity and conserves energy. This physiological shift is triggered by decreasing temperatures and shortening daylight, prompting the insect to seek protective microhabitats where humidity remains sufficient to prevent desiccation.
Typical refuges include:
- Leaf litter and forest floor debris, where insulation from snow and ground moisture maintain stable conditions.
- Soil layers a few centimeters below the surface, offering thermal buffering and reduced exposure to wind.
- Rodent burrows, rabbit warrens, and other mammalian nests that provide consistent warmth and high humidity.
- Under bark, within hollow logs, or in crevices of stones, especially for species that attach to vegetation during other seasons.
The overwintering stage varies among species. Adult females of Ixodes ricinus and Ixodes scapularis often shelter in leaf litter, while larvae and nymphs may remain in the upper soil strata or within rodent nests. Egg clusters deposited in protected substrates also endure the winter months without active development.
Key physiological adaptations support survival:
- Accumulation of cryoprotectants such as glycerol and trehalose, which lower the freezing point of body fluids.
- Enhanced synthesis of heat‑shock proteins that stabilize cellular structures during temperature fluctuations.
- Thickening of the cuticle, reducing water loss and providing a barrier against ice formation.
Geographic variation influences site selection. In milder climates, ticks may remain active at low temperatures and continue limited questing. In colder regions, they retreat deeper into the soil or exploit insulated animal burrows to avoid subzero conditions. Seasonal snow cover can act as an insulating layer, allowing ticks to survive at temperatures well below freezing without direct exposure.
Overall, successful winter persistence relies on a combination of behavioral choice of microhabitat, physiological depression of activity, and biochemical protection against cold stress. These mechanisms enable ticks to re‑emerge in spring, resume host‑seeking behavior, and continue their life cycle.