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Tick vectors and tick‐borne disease are increasingly impacting human populations globally. An important challenge is to understand tick movement patterns, as this information can be used to improve management and predictive modelling of tick population dynamics. Evolutionary analysis of genetic divergence, gene flow and local adaptation provides insight on movement patterns at large spatiotemporal scales. We develop low coverage, whole genome resequencing data for 92 blacklegged ticks, Ixodes scapularis, representing range‐wide variation across the United States. Through analysis of population genomic data, we find that tick populations are structured geographically, with gradual isolation by distance separating three population clusters in the northern United States, southeastern United States and a unique cluster represented by a sample from Tennessee. Populations in the northern United States underwent population contractions during the last glacial period and diverged from southern populations at least 50 thousand years ago. Genome scans of selection provide strong evidence of local adaptation at genes responding to host defences, blood‐feeding and environmental variation. In addition, we explore the potential of low coverage genome sequencing of whole‐tick samples for documenting the diversity of microbial pathogens and recover important tick‐borne pathogens such as Borrelia burgdorferi. The combination of isolation by distance and local adaptation in blacklegged ticks demonstrates that gene flow, including recent expansion, is limited to geographical scales of a few hundred kilometres. [ABSTRACT FROM AUTHOR]

The entomopathogenic nematode Steinernema riobrave has moderate impact on larval cattle fever tick, Rhipicephalus microplus, at semi-field conditions. Weekly foliar applications of in vitro-reared S. riobrave (BASF- Nemasys-R) sprayed on tick-infested potted buffelgrass killed significantly more larval ticks than water or the no treatment check (P<0.05). Use of a native nematode species like S. riobrave that occurs in the South Texas environment and has few, if any, effects on native flora/fauna is favored by conservation-focused organizations, especially in areas inhabited by threatened or endangered species. Additional research is proposed to evaluate impact of Nemasys-R at pasture conditions. Effective pasture treatment for questing R. microplus larvae is critical to support the USDA-APHIS Cattle Fever Tick Eradication Program in South Texas. El nemátodo entomopatógeno Steinernema riobrave tiene un impacto moderado sobre las larvas de la garrapata de la fiebre del ganado, Rhipicephalus microplus, en condiciones de semi campo. Las aplicaciones foliares semanales de S. riobrave (BASF-Nemasys-R) criado in vitro sobre pasto buffel en macetas infestado de garrapatas mataron significativamente más larvas de garrapatas que el agua o el control sin tratamiento (P<0.05). El uso de una especie de nemátodo nativo como S. riobrave, que se encuentra en el medio ambiente del sur de Texas y tiene pocos efectos, si es que tiene alguno, sobre la flora/fauna nativa, y es favorecido por organizaciones centradas en la conservación, especialmente en áreas habitadas por especies amenazadas, o en peligro de extinción. Se proponen investigaciones adicionales para evaluar el impacto de Nemasys-R en las condiciones de los pastos. El tratamiento eficaz de los pastos para las larvas de R. microplus es fundamental para apoyar el Programa de Erradicación de la Fiebre del Ganado del USDA-APHIS en el sur de Texas. [ABSTRACT FROM AUTHOR]

Reintroduction and dispersal of the livestock and wildlife pest, southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini), along the U.S.- Mexico border in the southernmost counties of Cameron and Willacy has been attributed mostly to nilgai antelope, Boselaphus tragocamelus (Pallas), and to a lesser extent, white-tailed deer, Odocoileus virginianus (Zimmerman). Nilgai are competent hosts of R. microplus, have large home ranges, and are distributed from southern Texas into northeastern Mexico where R. microplus, a vector of bovine babesiosis, is endemic. The study documents movement of nilgai and white-tailed deer through gaps in game fencing previously built to redirect movements of the endangered ocelot, Leopardus pardalis (L.), to wildlife crossings. Game fencing limits movement of nilgai and white-tailed deer and thus reduces the spread of cattle fever ticks. Additional game fencing is proposed to limit movement of tick-infested nilgai, white-tailed deer, and further redirect ocelots to crossings to avoid mortality on roads. In other parts of Cameron and Willacy counties where road mortality to ocelots is not an issue, game fencing is designed with large openings to block nilgai but allow free movement for endangered feline species. This research demonstrates how efforts to protect livestock from an exotic pest can also merge with goals of protecting endangered species in the same environment. [ABSTRACT FROM AUTHOR]

The scope of literature concerning tick-borne disease in South Dakota (SD) is limited primarily to case reports by public health officials. Published records of ticks occurring in the state are scarce and are mostly limited to reports of ticks opportunistically collected from wildlife, with little focus on surveillance for ticks themselves or potential pathogens. There exists only one published record with a compilation of the ticks of South Dakota (1983). Here, the current literature on the ticks of South Dakota, the pathogens they may carry, and their relevance and history in South Dakota are reviewed. Three new tick species documented in the state since the last publication are included herein, bringing the total number of tick species in the state to 21. I review and update past reports to include new county records and identification of pathogens previously undetected in the state and include some information on ongoing research involving ticks and tick-borne disease in the state. This manuscript and the projects referenced within were conducted with the goal of drawing attention to the need for tick surveillance in South Dakota. [ABSTRACT FROM AUTHOR]

Maintenance of sylvatic plague in prairie dogs ( Cynomis spp.) was once thought unlikely due to high mortality rates; yet more recent findings indicate that low-level enzootic plague may be maintained in susceptible prairie dog populations. Another hypothesis for the maintenance of sylvatic plague involves small mammals, other than prairie dogs, as an alternative reservoir in the sylvatic plague system. These hypotheses, however, are not mutually exclusive, as both prairie dogs and small mammals could together be driving sylvatic cycles of plague. The concept of a bridging vector has been used to explain the transmission of pathogens from one host species to another. In the case of sylvatic plague, this would require overlap in fleas between small mammals and prairie dogs, and potentially other species such as carnivores. Our goal was to evaluate the level of flea sharing between black-tailed prairie dogs ( Cynomis ludovicianus) and other small mammals in a mixed-grass prairie in South Dakota. We investigated the species richness of small mammals and small-mammal fleas in a mixed-grass prairie system and compared findings with previous studies from a short-grass ecosystem in Colorado. Over the summer field seasons 2014-2016 we live-trapped small mammals, collected fleas, and showed differences between both the flea and small mammal composition of the two systems. We also recorded higher densities of deer mice and lower densities of northern grasshopper mice in mixed versus shortgrass prairies. We confirmed, as is the case in shortgrass prairies, a lack of substantial flea species overlap on small mammal hosts and fleas from prairie dogs and their burrows. Moreover this study demonstrates that although small mammals may not play a large part in interepizootic plague cycling in shortgrass prairie ecosystems, their role in mixed-grass prairies requires further evaluation. [ABSTRACT FROM AUTHOR]

Background: Soft ticks (Family: Argasidae) are vectors of relapsing fever Borrelia in the United States and are potential vectors of African swine fever virus, a pathogen that could have a devastating effect on the U.S. swine industry if introduced to the U.S. mainland. Much of the tick-borne disease research in the U.S. focuses on hard ticks, and less is known about the ecology of soft ticks. Some soft tick species found in the southern U.S. have a wide host range and may feed on cattle, swine, native and exotic ungulates, small mammals, reptiles, and humans. Because the feeding habit of most soft tick species involves taking short, repeated blood meals that may include multiple host species, pathogen transmission among hosts is a concern both for human and animal health. Materials and Methods: Sampling was carried out at four locations in south Texas using dry ice traps placed in or near animal burrows and other sheltering cracks and crevasses that may provide refuge for soft ticks. Collected ticks were identified and subsequently screened for Rickettsia and Borrelia species and for host bloodmeal detection using conventional polymerase chain reaction and Sanger sequencing for pathogen and host species identification. Results: In total, 256 ticks of two Ornithodorinae species were screened. Borrelia species were identified in three samples. Bloodmeal detections were made in 22 tick specimens, representing eight vertebrate host species. Conclusions: Results demonstrate that the soft tick species detected herein feed on a range of wildlife hosts in south Texas and are associated with agents of human disease.

Sylvatic plague affects many species in North American prairie ecosystems. Deltamethrin is commonly used to manage fleas in potential outbreak areas. Understanding the role of small mammals and their ectoparasites in sylvatic plague maintenance is pertinent to understanding the ecology of plague and its persistence in nature. This study examined the effects of plague management using deltamethrin on communities of small mammals, their flea faunas, and Yersinia pestis prevalence. We trapped small mammals from 2014 to 2016 on the Lower Brule Indian Reservation (LOBR), South Dakota, and analyzed the effects of deltamethrin treatment on small mammal populations, flea loads, and Y. pestis prevalence. We collected higher flea loads from small mammals on sites not treated with deltamethrin (1.10 fleas per animal) than from deltamethrin-treated sites (1.03 fleas per animal). We observed significant negative trends in mean flea load per animal between pre- and post-treatment collections. We detected no significant effects of deltamethrin treatment on animal captures pre- and post-treatment, but observed significant differences in animal captures by experimental unit. We detected no serological evidence for the presence of Y. pestis antibodies in small mammals and 1.2% Y. pestis prevalence across all sampled fleas. Although there is little overlap in the species of fleas infesting small mammals and prairie dogs, the occurrence of flea spillover has been documented. In our study, treatment with deltamethrin reduced flea loads on small mammals by up to 49%. Our data suggest that although the efficacy of deltamethrin on the LOBR-a mixed-grass system-may not be as high as that found in a comparable study in a short-grass system, deltamethrin is still a useful tool in the management of plague.