Objective 1: Develop novel approaches and improve upon existing technologies for surveillance of ticks of medical importance. Objective 2: Develop novel approaches and improve upon existing technologies for control of ticks of medical importance. Objective 3: Conduct fundamental research on established and invasive ticks to understand the roles of tick species in disease transmission.
Molecular techniques will be either modified or developed to identify field specimens of four species of medically-important ticks, the pathogens they transmit, and remnant blood meals (from previous hosts) in questing (“flat”) ticks, collected by conventional means (dragging). Though not a pathogen, per se, mammalian meat allergy as it relates to ticks will also be investigated by existing and developed immunological means in an effort to understand this malady and to limit its impact on people. New tick repellents and formulations will be developed and the mechanism of repellent detection by ticks characterized. This will involve the optimization of an in vitro feeding system for ticks, using a silicone-based feeding system. The use of electrophysiological techniques to characterize tick responses to repellents and antifeedants will also be investigated using state-of-the-art equipment. A project to limit the negative impact of Lyme disease in human will be studied using tracking devices attached to deer (a host of ticks) and rodents (carriers of the Lyme Disease pathogen and other pathogens)The nature of the pathogen will be identified using molecular techniques initially with collaborators, and subsequently, in-house. Additionally, we will conduct molecular identification and artificial feeding studies with a newly-invasive parthenognetic tick and determine any pathogens this tick may acquire and transmit to humans.
Objective 1: ARS scientists in Beltsville, Maryland, worked to implement laboratory tools for molecular tick identification and testing ticks for pathogens, hired and initiated training for a new technician, and contracted renovations needed to make lab space fully functional for research. A new collaboration with Rutgers University was initiated to partner on the development of molecular tools for host identification from the relic blood meal in a tick. Objective 2: ARS scientists in Beltsville, Maryland, continued fieldwork according to the project plan for the areawide tick control project in Howard County, which tests the integrated pest management (IPM) approach to controlling transmission of tick-borne pathogens. The areawide project team completed tick sampling and mouse trapping work for the 2020 tick season and initiated work for the 2021 season; 2021 will be the final year for this areawide project. Tick and mouse tissue samples from the areawide project have been sent to CDC and Army Public Health Center for pathogen testing. Fieldwork was initiated to test artificial mouse nest boxes as a tool for surveillance and control tick-borne zoonotic pathogens that have their natural reservoirs in mice and cause human illnesses such as Lyme disease. These nest boxes are a technology that was developed by ARS scientists in Beltsville, Maryland, to facilitate host (mouse) targeted surveillance and control methodologies. An invention disclosure was submitted, and funding was received from the ARS Innovation Fund. In addition, a cooperative agreement with the University of Maryland was put in place to support field testing of a new deer feeding and treatment device in Montgomery County, Maryland. This Deer feeder is another host targeted control technology developed cooperatively by ARS scientists in Beltsville, Maryland, and University collaborators. A patent application was filed on the deer feeder technology in 2019. The development of these new hosts' targeted surveillance and control technologies will simplify surveillance and make control more targeted and efficient. ARS scientists in Beltsville, Maryland, developed a protocol for trapping white-tailed deer in suburbia to aid study of tick-host interaction. White-tailed deer are a keystone host of the blacklegged tick, the vector of pathogens that cause Lyme disease and other tick-borne diseases affecting humans in the United States. Development of novel host-targeted tick control technologies requires better understanding of deer-tick-pathogen interactions. It is difficult to trap white-tailed deer in suburban areas though these animals are critical for disease ecology studies. ARS scientists at Beltsville, Maryland, and University cooperators completed a two-year deer trapping study using drop nets in suburban areas of central Maryland. Deer trapping success was determined for sites with different forest and landscape features, as well as differing environmental conditions such as differing ambient temperatures and snow cover. The study was published as a white-tailed deer trapping protocol to provide a framework for future deer surveys. The recommendations from this study will help disease ecology researchers and wildlife biologists increase their deer capture success and the probability of parasite collection in areas across varying levels of urbanization and fragmentation. Objective 3: ARS scientists in Beltsville, Maryland, initiated efforts to implement an artificial tick feeding system for use in our laboratories. This artificial tick feeding system is another example of an ARS patented technology. Once this tick feeding system is up and running, it will be critically important for ongoing fundamental research on the development of bioassays for repellent, attractant, and toxicant research on native and invasive human-biting ticks.
1. U.S. populations of the Invasive Longhorned tick can transmit Cattle Theileria. The invasive Longhorned tick has spread rapidly in the eastern U.S.; in its native range, this tick is the vector of Oriental Thileriosis, an economically significant tick-borne disease of cattle caused by Theileria orientalis. Persistently infected cattle occur sporadically in the U.S., but transmission and subsequent disease do not occur without a vector. ARS scientists in Pullman, Washington, and Beltsville, Maryland, infected cattle with an isolate of T. orientalis collected from a Virginia farm and transmitted it via tick-borne transmission to uninfected calves to demonstrate that this invasive tick is a competent vector. Transmission of T. orientalis by this tick species represents a significant threat to the U.S. cattle population. The explosive spread of this tick species into areas where persistently infected cattle are present may lead to outbreaks of disease, resulting in severe economic burdens on cattle producers. These results provide valuable information for U.S. cattle producers and reinforce the need for continued surveillance and enhanced control measures for this invasive tick.
2. Surveillance of ticks and tick-borne pathogens in central Maryland revealed high levels of Borrelia burgdorferi infection in mice and immature ticks feeding on mice. Incidences of Lyme disease and other tick-borne diseases are increasing in the eastern United States. The white-footed mouse is a major reservoir for the Lyme disease pathogen (Borrelia burgdorferi) and a key host for the immature stages of the black-legged tick that transmits Lyme disease to humans. As part of an areawide effort to develop integrated strategies to control tick vectors, ARS scientists at Beltsville, Maryland, conducted surveillance of ticks and tick-borne pathogens by collecting free-living ticks from vegetation and trapping mice from seven field sites in central Maryland. This study revealed high infection rates of Borrelia burgdorferi in captured mice (58.8%) and in ticks removed from mice (71.1%). The findings underscore the importance of control measures targeting mice in breaking the cycle of pathogen transmission and the life cycle of the vector ticks. Public health departments in the State of Maryland, tick and Lyme disease researchers, and companies that develop host-targeted tick control technologies will benefit from the precise, updated information on ticks and tick-borne pathogens from this study in Maryland.
Milholland, M.T., Xu, G., Rich, S.M., Machtinger, E.T., Mullinax, J.M., Li, A.Y. 2021. Coinfections in ixodes scapularis from white-tailed deer compared to questing ixodes infer facultative mutualism across sites in Maryland, USA. Vector-Borne and Zoonotic Diseases. https://doi.org/10.1089/vbz.2020.2644.
Roden-Reynolds, P., Machtinger, E.T., Li, A.Y., Mullinax, J.M. 2020. Trapping white-tailed deer (Artiodactyla: cervidae) in suburbia for study of tick-host interaction. Journal of Insect Science. https://doi.org/10.1093/jisesa/ieaa044
Milholland, M.T., Eisen, L., Nadolny, R.M., Hojgaard, A., Machtinger, E.T., Mullinax, J.M., Li, A.Y. 2021. Surveillance of ticks and tick-borne pathogens in suburban natural habitats of central Maryland. Journal of Medical Entomology. https://doi.org/10.1093/jme/tjaa291.
Dinkel, K.D., Herndon, D.R., Noh, S.M., Lahmers, K.K., Todd, M.S., Ueti, M.W., Scoles, G.A., Mason, K.L., Fry, L.M. 2021. A U.S. isolate of Theileria orientalis, Ikeda genotype, is transmitted to cattle by the invasive Asian longhorned tick, Haemaphysalis longicornis. Parasites & Vectors. 14. Article 157. https://doi.org/10.1186/s13071-021-04659-9.