Duration of exposure to suboptimal atmospheric moisture affects nymphal blacklegged tick survival.

The biological processes affecting Ixodes scapularis Say survival are complex. Understanding these processes will be beneficial for predicting tick distribution and population dynamics. This research shows that the duration for which nymphal ticks are exposed to drying air is an important factor for their survival. Experimental analysis of variance results show that duration of exposure to dry air (duration) is as important as vapor pressure deficit (relative humidity) (duration, relative humidity, P < 0.0001). Ticks do not survive when exposed to dry air for long periods; however, the return of humid air within 4-8 h has as large a positive impact on tick survival, as does constant humid air. This experiment exposes nymphal ticks to conditions of suboptimal humidity for different durations and then returns them to saturated conditions that are more typical of daily relative humidity fluctuations experienced during summer in southern New England forests.