The Influence of Relative Humidity, Temperature, and Light Cycling on Winter Tick Questing at Four Geographic Locations

Abstract

By Hayley Prosser, Biological Sciences

Advisor: Joshua Benoit

Presentation ID: 93

Abstract: In recent years, moose populations have been declining due to an increase in winter ticks, Dermacentor albipictus, which cause anemia and hair loss in moose during feeding, leading to high mortality rates for calves. During the fall, tick larvae climb vegetation in search of a host; a behavior known as questing. Analyzing the factors that may trigger questing will narrow down the conditions when ticks are outside of protected microhabitats, and pest control efforts could be more fruitful. In this study, we measured questing in response to environmental stimuli in tick larvae from four geographic locations. Specifically, larvae were placed under varying environmental conditions, including temperature, relative humidity, and daylength. We predicted increased temperature variability and decreased relative humidity and daylength would trigger larval questing. We found no significant difference in questing in response to changes in daylength, but increased temperature variability, and lower relative humidity played an important role in triggering questing behaviors. We also found a significant difference in proportion of questing ticks depending on the collection site, hinting that endogenous molecular signals may drive this behavior. Altogether, endogenous mechanisms and environmental factors both play a key role in tick questing.