Effects of Humidity on Survival and Metabolism of the Gulf Coast Tick (Amblyomma maculatum)
Abstract/Description/Artist Statement
Amblyomma maculatum (Gulf Coast tick; GCT) is an ixodid tick historically distributed throughout the southeastern United States. During the last 50 years, the range of the GCT has rapidly expanded and populations are now found as far north as Connecticut and Illinois. The GCT is a primary vector of Rickettsia parkeri, which causes R. parkeri rickettsiosis, a spotted fever illness. Ticks feed on hosts once between each of their three life stages, and stored lipids are the primary energy source for survival between blood meals. Ticks are sensitive to water loss, and conditions of low relative humidity (RH) lead to decreased survival. Increased lipid catabolism may be related to RH-induced stress, and/or water released by lipid metabolism may offset losses to the environment.
This study quantified effects of controlled RH on lipid usage and survival in unfed adult A. maculatum. Ticks were randomly assigned to five humidity treatments ranging from optimal (~85–100% RH) to desiccating conditions (~45–60% RH) and maintained at ~22°C for up to three months. At one month intervals, lipid content of ticks was determined with chloroform extraction and weighing with an ultramicrobalance.
We hypothesized that lower RH would be associated with 1) greater lipid loss and 2) reduced survival. Preliminary findings demonstrate elevated mortality with decreasing relative humidity; however, the relationship between RH and lipid usage is equivocal. Understanding how abiotic stresses such as humidity affect lipid metabolism can provide critical insight into tick survival, geographic expansion, and tick-borne pathogen risk under changing climate conditions.
Faculty Advisor/Mentor
David Gauthier
Faculty Advisor/Mentor Email
dgauthie@odu.edu
Faculty Advisor/Mentor Department
Biological Sciences
College/School Affiliation
College of Sciences
Student Level Group
Undergraduate
Presentation Type
Poster
Effects of Humidity on Survival and Metabolism of the Gulf Coast Tick (Amblyomma maculatum)
Amblyomma maculatum (Gulf Coast tick; GCT) is an ixodid tick historically distributed throughout the southeastern United States. During the last 50 years, the range of the GCT has rapidly expanded and populations are now found as far north as Connecticut and Illinois. The GCT is a primary vector of Rickettsia parkeri, which causes R. parkeri rickettsiosis, a spotted fever illness. Ticks feed on hosts once between each of their three life stages, and stored lipids are the primary energy source for survival between blood meals. Ticks are sensitive to water loss, and conditions of low relative humidity (RH) lead to decreased survival. Increased lipid catabolism may be related to RH-induced stress, and/or water released by lipid metabolism may offset losses to the environment.
This study quantified effects of controlled RH on lipid usage and survival in unfed adult A. maculatum. Ticks were randomly assigned to five humidity treatments ranging from optimal (~85–100% RH) to desiccating conditions (~45–60% RH) and maintained at ~22°C for up to three months. At one month intervals, lipid content of ticks was determined with chloroform extraction and weighing with an ultramicrobalance.
We hypothesized that lower RH would be associated with 1) greater lipid loss and 2) reduced survival. Preliminary findings demonstrate elevated mortality with decreasing relative humidity; however, the relationship between RH and lipid usage is equivocal. Understanding how abiotic stresses such as humidity affect lipid metabolism can provide critical insight into tick survival, geographic expansion, and tick-borne pathogen risk under changing climate conditions.