Date of Award
Master of Science
Entomology and Plant Pathology
Rebecca Trout Fryxell
Margaret Staton, Jennifer DeBruyn
Despite the risks that ticks and tick-borne disease pose to the beef cattle industry, many Tennessee producers are unaware of the dangers they represent. This mindset could facilitate the invasion and establishment of exotic ticks and pathogens that would devastate the cattle industry. Current control practices rely on chemical methods, which are not effective long-term; therefore, investigations into creating an integrated approach to control would create more sustainable methods. This study aims to address this through two objectives: The first is to determine the species composition, seasonal prevalence, geographic distribution and diversity of ticks on Tennessee cattle. The second is to elucidate the core microbial community of Amblyomma maculatum and determine differences associated with blood-feeding, collection location, and sex. Ticks were collected from cattle at University of Tennessee research and education centers (REC), through an extension agent survey, and livestock auctions. 25% of the herd or 10 animals were sampled (IACUC# 2192, IBC# 384-15) whichever was greater. The V3-V4 region of the 16S rRNA segment of bacterial genomes was amplified using the Illumina MiSeq platform. Mothur 1.33.2 was used in conjunction with the statistical software R (v3.3.0) to investigate the microbiome of A. maculatum. SAS software (9.4) was used to answer questions from objective one. Our results demonstrated that four tick species were parasites of beef cattle: Amblyomma americanum, Amblyomma maculatum, Dermacentor variabilis, and Ixodes scapularis. Seasonal impacts were not shown to have an impact on either infestation prevalence or burden of any tick species, although region of collection did have an effect on the infestation prevalence and burden of both the Total and Amblyomma maculatum. Co infestation was rare, although D. variabilis was commonly found feeding with A. americanum. Several core microbial inhabitants of A. maculatum matched previous investigations, with sex, feeding status significantly influencing alpha diversity. Results suggested that A. americanum is a widespread and abundant pest of cattle, and added further support that the bacteria Francisella is an endosymbiot of A. maculatum. Ultimately, investigating tick diversity and microbiome composition will improve existing control efforts and prepare cattle producers for invasive ticks and pathogens.
Theuret, David Paul, "Surveillance of ticks parasitizing Tennessee beef cattle and investigations into the microbial communities of cattle associated and questing Amblyomma maculatum. " Master's Thesis, University of Tennessee, 2017.