Trapping Methods for Ixodid Ticks and Pathogen Associations of <i>Amblyomma maculatum</i> (Gulf Coast Tick) in Western Tennessee

Ticks are vectors of disease agents and pests of humans and animals. Various methods are used for tick monitoring and pathogen surveillance to assess tick distributions, pathogen prevalence and control measures, such as monitoring the changing geographic distribution of the Gulf Coast tick, Amblyomma maculatum. This project (1) compared the effectiveness of six trapping methods for the collection of hard (Ixodid) ticks in a typical grassland-forest habitat in southwestern Tennessee, and (2) examined pathogen associations of A. maculatum collected in western Tennessee.

To compare trapping methods across time and habitat types, a temporal study was conducted in 2013 and a habitat study was conducted in 2014. Conventional tick collection methods (dragging, flagging, dry ice trapping, and sweep-netting) and novel methods (carbon dioxide (CO₂)-reinforced dragging and flagging) were compared across five monthly sampling periods. Dragging, CO₂ dragging, CO₂ flagging and dry ice trapping were then compared across four habitat types (grassland, upland deciduous, bottomland deciduous, and coniferous). Significant interactions between trapping method and sampling period (2013) and between trapping method and habitat (2014) were identified. In both studies, the novel methods were comparable to their conventional counterparts; the addition of CO₂ did not significantly increase the number of ticks collected. Dry ice trapping and dragging were effective methods of tick collection across time and habitat types, and were among the most effective methods for all species collected.

To detect pathogens associated with A. maculatum and identify the best surveillance methods for monitoring infected ticks, questing and host-feeding A. maculatum (n = 265) collected in the 2013 and 2014 trapping studies and other concurrent studies were PCR-screened for Rickettsia, Ehrlichia, and Borrelia species. Of the A. maculatum screened, none were Borrelia positive, 2 were Ehrlichia positive, and 60 were infected with R. parkeri (a pathogenic Rickettsia). No particular surveillance technique (e.g. habitat type or collection source) was significantly more effective for detection of infected A. maculatum. The results of this project demonstrate the importance of monitoring and surveillance methods based upon habitat, target species, and research objectives, and the need for continued monitoring and surveillance of ticks, including A. maculatum.