Larval thermal characteristics of multiple ixodid ticks underlie their range dynamics

Temperature is a major factor that impacts tick populations by limiting geographic range of different species. Little is known about the thermal characteristics of these pests outside of a few studies on survival related to thermal tolerance. In this study, thermal tolerance limits, thermal preference, impact of temperature on metabolic rate, and temperature-activity dynamics were examined in larvae for six species of ixodid ticks. Tolerance of low temperatures ranged from −15 to −24°C with surviving at the lowest temperatures. High temperature survival ranged from 41 to 47 °C, with having the highest upper lethal limit. showed the lowest survival at both low and high temperatures. Thermal preference temperatures were tested from 0-41°C. exhibited a significant distribution of individuals in the lower temperatures, while the majority of other species gathered around 20-30°C. Activity was measured from 10-60°C, and the highest activity was observed in most species was near 30°C. Metabolic rate was the highest for most species around 40°C. Both activity and metabolic rate dropped dramatically at temperatures below 10°C and above 50°C. In summary, tick species vary greatly in their thermal characteristics, and our results will be critical to predict distribution of these ectoparasites with changing climates.