Lipid Use in Blacklegged Ticks (Ixodes scapularis): Response to Aging, Infection, and Changing Weather Patterns
The blacklegged tick, Ixodes scapularis, is prevalent throughout the northeastern and upper midwestern U.S. This tick is the primary vector of Borrelia burgdorferi, the causative agent of Lyme disease, as well as Anaplasma phagocytophilum, and Babesia microti, the causative agents of human granulocytic anaplasmosis and babesiosis, respectively. Ticks expend energy while host-seeking and must consume blood to advance to the next life stage. This energy is derived from lipids that sustain the tick until it finds the next host. The goal of this dissertation was to explore lipid use in blacklegged ticks, determine the best method for measuring blacklegged tick aging, determine whether infection influences lipids, and explore whether changing weather patterns may affect lipid usage. The morphometric age ratio did correlate significantly with total tick lipid content; however, the predictive value of the ratio was not reliable; chloroform extraction results showed that lipid amounts declined steadily and more accurately characterized the physiological condition I. scapularis. The winter preceding the nymphal active season is important in determining how ticks preserve their lipid resources for use during the following active season. Implications of climate change on the distribution of blacklegged ticks are discussed. In a laboratory study, I found that ticks which fed on locally-captured mice had a significantly greater molting success rate and significantly more total lipid than ticks that fed on laboratory-raised mice. Ticks that tested positive for infection with B. burgdorferi, A. phagocytophilum, and/or Ba. microti had a larger body size than uninfected ticks, however, this was not significantly different. There was no clear benefit when ticks collected in the field in 2012 and 2013 were analyzed for infection and lipids. Long-term studies are needed to clarify any effects that infection may have on tick survival and population trends. Furthermore, understanding how blacklegged ticks, the most important arthropod vectors in the U.S., respond to environmental change in both the short term (i.e., in a given year) and long term (multi-year trends) may provide insight not only into how vector-borne disease risk may change over time but more generally, how other common arthropods adapt to climate change as well.
Pool, Justin Ryan, "Lipid Use in Blacklegged Ticks (Ixodes scapularis): Response to Aging, Infection, and Changing Weather Patterns" (2017). ETD Collection for Fordham University. AAI10620983.