Abiotic Factors Contributing to the Survival of Three Tick Species in Southeastern Virginia, Amblyomma Americanum (Lone Star Tick), Dermacentor Variabilis (American Dog Tick), and Amblyomma Maculatum (Gulf Coast Tick)
Date of Award
Master of Science (MS)
Holly D. Gaff
Larry P. Atkinson
Amblyomma americanum, Amblyomma maculatum, and Dermacentor variabilis are hard-bodied ticks in the Hampton Roads area of southeastern Virginia. This study consisted of two field projects focused on these tick species. To estimate the off-host survival of local tick species, a capture-mark-recapture (CMR) study was performed. An environmental survival study was performed to quantify the ability of these three tick species to survive in situ. Four field sites were used in the Hampton Roads region covering a variety of habitat types and vegetation; specifically two drier, upland field sites and two flood-prone sites. CMR was conducted from May through September at two field sites in 2014 (one dry, one wet), then all four sites in 2015. The environmental survival study was conducted May through September of 2015 at all four sites.
CMR ticks were captured on flags, marked with fingernail polish, and returned to the location of capture. Amblyomma americanum was the dominant species collected (95% in 2014, 87% in 2015) when compared to the other tick species collected: D. variabilis, A. maculatum, and Ixodes spp. In 2014, 1 D. variabilis female and 32 A. americanum ticks were recaptured. One A. americanum nymph and 1 D. variabilis female were recaptured an additional time. For A. americanum, the average time-to-recapture was 30 days with a maximum of 71 and a minimum of 8 days. Only 1 male A. americanum tick was recaptured in 2015, 27days post initial marking.
In the environmental survival study, A. americanum, D. variabilis, and A. maculatum ticks were placed inside environmental containers in situ over four months. The containers were checked at fixed intervals to quantify survival. A Cox Regression survival analysis indicated there is a significant difference in survival between species across all field sites. There is a 50.5-times higher risk of mortality for A. maculatum compared to A. americanum, a 4.3-times higher risk of mortality for A. maculatum compared to D. variabilis, and an 11.9-times higher risk of mortality for D. variabilis compared to A. americanum. There is also significantly higher mortality in field sites prone to flooding than in drier, upland field sites.
Bidder, Lindsey A., "Abiotic Factors Contributing to the Survival of Three Tick Species in Southeastern Virginia, Amblyomma Americanum (Lone Star Tick), Dermacentor Variabilis (American Dog Tick), and Amblyomma Maculatum (Gulf Coast Tick)" (2016). Biological Sciences Theses & Dissertations. 16.
Available for download on Friday, January 25, 2019