Date of Award
Bachelor of Science
Lyme disease, tick, Ixodes scapularis, carbon isotopes, nitrogen isotopes, stable isotope analysis, bloodmeal analysis
One of the most enigmatic concepts in tick-borne disease ecology is how to identify the prior host of a questing tick. The ability to do so would provide predictions to directly aid in controlling the spread of the many tick-borne pathogens, including the bacterial spirochete Borrelia burgdorferi, which causes Lyme disease in humans. I explored the application of a novel technique, stable isotope analysis (SIA), to identify the most recent host in molted Ixodes scapularis (black-legged tick). The common reservoir and feeding host, Peromyscus leucopus (white-footed mice; n = 46), were trapped, infested with nymphal ticks, and fed restricted diets, simulating feeding guilds, to confirm previous findings regarding the temporal enrichment of δ13C and δ15N in molted adults. Over a feeding period of up to seven days, δ13C was found to be significantly higher in molted ticks that fed on animals on a corn diet than wild (p = 0.014), standard (p = 0.013), and meat diets (p = 0.002), but was not significantly different in δ15N (Tukey HSD). To directly test the feasibility of SIA to identify prior hosts, I used isotopic data from multiple years of research to generate a k-means cluster analysis model using isotopic signatures from ticks fed on standard-fed and wild-fed hosts, organized by both feeding guild and species. I then tested the model using field-collected ticks. Seventy-two percent of field-collected ticks fell into the model’s five 95% confidence ellipses. I propose the potential application of SIA to the identification of a prior host in questing ticks as an alternative or enhancement to DNA-based methods in the trophic ecology of tick-borne diseases.
Welles, Imogene, "Exploration of Stable Isotope Analysis to Identify Prior Host in Ixodes scapularis" (2020). Honors Theses. 2371.