When do ticks go into dormancy in summer? - briefly
Ticks typically enter summer diapause when sustained daytime temperatures exceed 25 °C and relative humidity falls below 70 %, a condition usually reached in mid‑June to early July in temperate zones. After this period, activity resumes only when cooler, more humid conditions return.
When do ticks go into dormancy in summer? - in detail
Ticks enter a state of reduced activity during the hottest part of the year when temperature and humidity reach levels that limit their ability to locate hosts. The onset of this summer dormancy varies among species, regions, and microclimates.
In temperate zones, adult females of Ixodes ricinus typically cease questing when daily maximum temperatures exceed 30 °C and relative humidity falls below 70 %. Activity resumes after a cooling period of at least three consecutive days with temperatures under 25 °C and humidity above 80 %. Nymphs display a similar pattern but may remain active at slightly higher humidity thresholds (≈75 %).
Hard‑ticks in arid environments, such as Dermacentor variabilis, initiate dormancy earlier in the season. When ground temperature reaches 28 °C and soil moisture drops below 10 %, larvae and nymphs retreat to the leaf litter, remaining inactive until moisture levels rise above 15 % and temperature declines to 22–24 °C.
Key factors influencing the timing of summer dormancy:
- Ambient temperature: sustained values above species‑specific thresholds suppress host‑seeking behavior.
- Relative humidity: low atmospheric moisture accelerates dehydration risk, prompting retreat.
- Photoperiod: longer daylight hours correlate with higher temperatures, indirectly affecting dormancy onset.
- Habitat moisture: shaded, moist microhabitats delay dormancy; exposed, dry sites trigger it sooner.
Geographic variation modifies these thresholds. In Mediterranean climates, ticks may enter dormancy as early as May, whereas in northern Europe dormancy often begins in July. Altitudinal gradients also shift timing; higher elevations experience cooler summers, extending the active period.
Physiological changes accompany dormancy. Ticks reduce metabolic rate by up to 80 %, close spiracular plates to limit water loss, and accumulate protective proteins such as heat‑shock proteins. These adaptations enable survival until favorable conditions return.
Understanding the precise timing of summer dormancy assists in predicting tick‑borne disease risk and informs control strategies, such as timing acaricide applications to target active periods.