Fig 1.
Each cylinder represents a plastic tube containing one tick, and each rectangle represents an airtight container with a constant RH maintained by a humidity control pack. There were nine distinct groups based on species and RH. Each container with six ticks was replicated four times for a total sample of 24 ticks per group.
Fig 2.
Confirmation of experimental climates.
A HOBO Data Logger recorded temperature and RH hourly, confirming our setup worked as intended. The plot shows data for six days with temperature cycling between 20°C and 30°C, and RH remaining constant inside each container at approximately 32%, 58%, or 84%.
Fig 3.
Survivorship of ticks in nine experimental groups.
All within-species comparisons, and all between-species comparisons at the same RH, showed significant differences in survivorship (P < 0.05), except between Amblyomma and Dermacentor at RH84 (P = 0.55).
Table 1.
AIC analysis of general linear models describing the influence of species and relative humidity on tick survivorship.
Fig 4.
Questing heights of individual ticks in nine experimental groups.
Each dot represents a single instance of tick questing; horizontal lines represent the average questing heights of each group. Questing height was negatively associated with RH in Amblyomma (H = 24.765, df = 2, P < 0.001), positively associated with RH in Dermacentor (H = 11.248, df = 2, P = 0.004), and not associated with RH in Ixodes (H = 5.065, df = 2, P = 0.079).
Fig 5.
Questing frequencies in nine experimental groups.
Each dot represents the proportion of ticks questing out of all living ticks within each experimental group on a particular day; the horizontal lines represent the average questing frequencies of each group. Questing frequency increased with drier conditions in Dermacentor (H = 8.792, df = 2, P = 0.012), but not in Amblyomma (H = 3.026, df = 2, P = 0.220) or Ixodes (H = 0.194, df = 2, P = 0.908).