Research Project: Integrated Pest Management of Cattle Fever Ticks

Location: Cattle Fever Tick Research Unit

2023 Annual Report

Objectives
Objective 1 Develop population genetic and ecological methods to improve cattle fever tick surveillance. Objective 2: Develop methods to control ticks using biocontrol, botanicals and new acaricides.

Approach
Cattle fever ticks, Rhipicephalus microplus and R. annulatus, are invasive pests that remain a threat to the livestock industry. They were eradicated from the United States in 1943; however, they remain established in Mexico and these populations tend to recolonize suitable habitats north of the Rio Grande. Cattle fever ticks transmit the microbes that cause bovine babesiosis and anaplasmosis. Significant cattle damage and economic loss would result if bovine babesiosis re-emerged in the United States. Research on new technologies to improve Integrated Pest Management (IPM) of cattle fever ticks is needed for implementation in the Cattle Fever Tick Eradication Program (CFTEP). This Program is operated in the Permanent Quarantine Zone established in south Texas along the Rio Grande to eliminate incursions from Mexico. The overall goal of this project is to conduct research on risk assessment and biology, surveillance, control, and monitoring and sustainability to improve integrated cattle fever tick management. The outcomes of this research will be effective, long-term adaptable technological solutions for the challenges that the CFTEP is facing. These include climate variability, acaricide resistance, involvement of native and exotic wildlife as alternative tick hosts, and the economic impact of tick outbreaks. The project will also benefit transdisciplinary efforts to achieve optimal health for animals, humans, and the environment, a concept known as “One Health”, by adapting this research to tick disease vectors expanding their range and exotic ticks that threaten animal and human health in the United States.

Progress Report
In support of Subobjective 1A, integrate cattle fever tick (CFT) genetic data with geographic information system (GIS) tools to enhance understanding of the geographic source and population structure of CFT causing outbreaks, ARS scientists have continued collaborative efforts with scientists at the Pathogen and Microbiome Institute, Northern Arizona University, to assess the presence of sequence variations associated with CFT resistance to permethrin as well as sequence variations that help distinguish geographically separated populations of CFT. Results are routinely provided to the USDA-APHIS-VS Cattle Fever Tick Eradication Program (CFTEP) and the Texas Animal Health Commission (TAHC) in support of programmatic efforts. Additionally, CFT have been collected from nilgai antelope for whole genomic DNA extraction and molecular analyses. In support of Subobjective 1B, enhance GIS-based tools for CFT surveillance, ARS researchers partnered with the ARS Partnerships for Data Innovations (PDI) team to complete the development of a FieldMaps tool for the CFTEP to streamline data entry and provide real-time access to the CFT infestation database. This FieldMaps tool has been officially launched for use by the CFTEP with over 100 CFTEP field inspectors in eight different county work areas having access to this tool for real-time entry of CFT infestation data. This system allows CFTEP inspectors in the field to record CFT outbreak data from their phones directly to an online map layer that can be instantly accessed by program personnel and ARS researchers. This FieldMaps tool has significantly decreased data entry workflow, enabled rapid identification of at-risk areas in south Texas, and allowed for faster programmatic decision making. In support of Subobjective 2C, develop novel, and refine existing, CFT sampling methods, field research was conducted to improve surveillance techniques for sampling larval CFT in the environment. Unlike most other species of ticks which are found questing in nature as adults, CFT only quest for hosts in the larval stage making standard surveillance and detection methods inadequate for CFT. Additionally, these standard collection techniques, such as cloth tick drags, tend to expose the investigator to environmental hazards. ARS researchers in Edinburg, Texas, with collaborators from Old Dominion University, experimented with two mechanical devices, a tick vac and a tick-bot, to collect larval ticks in the field. Understanding the survival of immature CFT while they are off host in the environment is critical for managing CFT in Texas and for setting CFTEP and TAHC eradication policies, particularly as Texas experiences drastic weather due to climate extremes. ARS researchers completed pasture studies to evaluate the effect of ecological factors on the survival and longevity of off host stages of CFT in south Texas by evaluating factors such as temperature, habitat, and humidity on the survival of Rhipicephalus annulatus and R. microplus. In support of Subobjective 2A, refine the remotely activated sprayer to treat CFT infestations in nilgai and white-tailed deer, entomopathogenic nematodes were laboratory and field tested for eradication of questing CFT larvae in pastures. The nematodes showed a high-level of efficacy against CFT larvae on shaded potted buffelgrass, but only moderate activity under open full sun conditions. Further research is planned using an adjuvant, Barricade®, that reduces UV and desiccation of nematodes after they are applied to foliage. Entomopathogenic nematodes could be a new tool for the CFTEP to use for treatment of pastures. Discussions are in progress with the collaborating nematode producer for use by the CFTEP in 2024. Additionally, a commercially built, remotely operator sprayer, the 3D Quikhand®, was shown to be effective in treatment of cattle with both Steinernema riobrave entomopathogenic nematodes or the botanical acaricide Stop the Bites®. This sprayer could potentially be used to treat CFT tick infested cattle or wildlife as they approach water troughs or fence gaps. Treatment of CFT wildlife hosts such as WTD and nilgai could be accomplished in sections of the Temporary Quarantine Area now that newly constructed strategic game fencing has been constructed which limits long distance movements of infested wildlife. In support of Subobjective 2C, evaluate natural botanicals, abrasives, and desiccants against CFT for use in sensitive wildlife areas, in vivo and in vitro studies were continued to evaluate the efficacy of commercially available desiccant dusts (Deadzone®, Drione®, and EcoVia®) and botanical products (nootkatone, cedar oil, and Stop the Bites®) for controlling CFT. Laboratory and cattle stall trials demonstrated that desiccant dust products, Deadzone (renamed Celite 610, a diatomaceous earth product), Drione (silica gel + pyrethrins + piperonyl butoxide synergist), and EcoVia (silica gel + thyme oil), with and without bioactive botanical additives, when applied dry were strongly lethal to larval CFT in the laboratory and after being released on dust-treated cattle. Nootkaone and Stop the Bites® were found to be highly efficacious against CFT in the laboratory and in vivo testing of nootkatone to determine the effective treatment dosage for cattle has begun. In support of Subjective 2D, discover and evaluate classical biological control agents for CFT, ARS scientists with partners in Hanoi, Vietnam, conducted field studies to search for parasitoids of CFT. CFT exposures were conducted in a minimum of six locations in northern Vietnam. Potentially parasitized CFT were collected and kept alive or put into ethanol for emergence of the parasitoid or molecular screening. Live-exposed larvae, nymphs, and adults were brought back to the U.S. for visual analyses and molecular screening. Whole genomic extractions from approximately 200 engorged nymphs and determination of appropriate molecular methods for the detection of parasitoids has conducted. Initial molecular screening for parasitoids has not detected the presence of parasitoids, but additional studies and CFT collections are planned to maximize the possibility of collecting parasitized CFT. In support of Subobjective 2E, evaluate novel long-acting (LA) acaricide formulations to reduce the number of systematic treatments needed to manage cattle fever tick infestations, studies were conducted to evaluate the therapeutic and residual efficacy of a pour-on formulation of fluralaner for controlling CFT infesting cattle. Additional studies to evaluate fluralaner for controlling Amblyomma mixtum are planned for early FY24. Efficacy data from pasture studies to evaluate varying doses of macrocyclic lactones (doramectin, eprinomectin, and moxidectin) for CFT control as well as pharmacokinetic data were analyzed. If efficacious, these treatments could reduce the number of treatments needed to manage cattle fever tick infestations on quarantined cattle reducing treatment costs and losses due to animal injury. Additionally, ARS researchers process incoming live CFT samples from outbreak premises in south Texas. Viable engorged female CFT are allowed to lay eggs and the larval stages are then assayed with Larval Packet Tests against a panel of acaricides to determine levels of acaricide resistance. The degree of resistance was measured and reported weekly to CFTEP program managers to assist with regulatory decisions. DNA samples from these ticks are also used to assay for genetically determined target resistance as well as using population genetic markers for traceback studies for the source of new outbreaks. ARS researchers in collaboration with Texas A&M University also worked to characterize R. microplus extracellular vesicles. Extracellular vesicles were isolated and transmission electron microscopy was used to observe the characteristic morphology and size of the tick exosomes. Vesicles were purified from salivary gland and midgut cultures from female and male ticks. Western blot analysis of the vesicle preparations confirmed the expression of the exosome markers CD63, ALIX, TSG101, and Hsp70 supporting the secretion of exosome from R. microplus organs. These results indicate that tick extracellular vesicles contain a core set of proteins that are found within midgut and salivary glands.

Accomplishments
1. Interaction between anti-tick vaccine and moxidectin improves cattle fever tick control. Cattle fever ticks (CFT) are one of the most economically important ectoparasites of cattle worldwide. Controlled studies were completed to directly compare efficacy of anti-tick vaccination with the tick gut protein Bm86 with and without systemic acaricide. Results showed that the Bm86 anti-tick vaccine in combination with moxidectin expressed a synergistic interaction, providing greater and longer efficacy than either treatment alone. This treatment combination may be of benefit for use in the field by the Cattle Fever Tick Eradication Program and beef producers worldwide.

2. Game fencing limits wildlife movement reducing the spread of cattle fever ticks. Wildlife like nilgai antelope that utilize movement corridors may be dispersing cattle fever ticks and the pathogens they carry into the transboundary region between the U.S. and Mexico. To mitigate this risk, ARS researchers in Edinburg, Texas, worked with collaborators from USDA-Animal and Plant Health Inspection Service (APHIS), U.S. Fish and Wildlife Services, and the Texas Animal Health Commission to build game fencing in Cameron County to block northward movement of nilgai and associated ticks/pathogens. This fencing also redirects endangered ocelots to existing U.S. Fish and Wildlife tunnels for safe passage across major highways.

3. Periviscerokinin receptor silencing in cattle fever ticks. Cattle fever ticks (CFT) vector pathogens that cause serious diseases in cattle, worldwide. There is an urgent need to develop new and effective methods for CFT control. G-protein coupled receptors (GPCRs) in ticks are involved in regulating tick development and reproduction and offer potential for development of novel chemical acaricides. New research utilizing gene silencing of tick GPCRs conducted by ARS researchers in Kerrville, Texas, in collaboration with Texas A&M University revealed the potential of several GPCRs to alter tick physiological processes resulting in reduced tick fitness and reproduction.

Review Publications
Arocho Rosario, C.M., Miller, R.J., Klafke, G.M., Coats, C., Grant, W.E., Samenuk, G., Yeater, K.M., Tidwell, J.P., Bach, S., Perez De Leon, A.A., Teel, P.D. 2022. Interaction between anti-tick vaccine and a macrocyclic lactone improves acaricidal efficacy against Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae) in experimentally infested cattle. Wildlife Research. https://doi.org/10.1016/j.vaccine.2022.10.001.
Showler, A. 2022. Effects of compost on onion quality, yield, and thrips infestation. Environmental Systems Research Institute Users Conference Proceedings. https://doi.org/10.1186/s40068-022-00268-2.
Egiza, A., Maestas, L.P. 2022. Where have all the grouse ticks gone? Apparent decline in collections of Haemaphysalis chordeilis Packard during the 20th century. International Journal for Parasitology: Parasites and Wildlife. https://doi.org/10.1016/j.ijppaw.2022.11.007.
Showler, A., Harlien, J.L. 2023. Desiccant dusts, with and without bioactive botanicals, lethal to Rhipicephalus (Boophilus) microplus Canestrini (Ixodida: Ixodidae) in the laboratory and on cattle. Journal of Medical Entomology. https://doi.org/10.1093/jme/tjad010.
Temeyer, K.B., Schlechte, K.G., Gross, A.D., Lohmeyer, K.H. 2023. Identification, baculoviral expression and biochemical characterization of a novel cholinesterase of Amblyomma americanum (Acari: Ixodidae). International Journal of Molecular Sciences. https://doi.org/10.3390/ijms24097681.
Wulff, J.P., Temeyer, K.B., Tidwell, J.P., Schlechte, K.G., Lohmeyer, K.H., Peitroantonio, P.V. 2022. Periviscerokinin (Cap2b; CAPA) receptor silencing in females of Rhipicephalus microplus reduces survival, weight, and reproductive output. Parasites & Vectors. https://doi.org/10.1186/s13071-022-05457-7.
Dos Santos, E.G., Dos Santos Bezerra, W.A., Temeyer, K.B., Perez De Leon, A.A., Costa-Juior, L.M., Dos Santos Soares, A.M. 2021. Effect of essential oils on native and recombinant acetylcholinesterase of Rhipicephalus microplus. Brazilian Journal of Veterinary Parasitology. 30. Article e002221. https://doi.org/10.1590/S1984-29612021024.
Goolsby, J., Moran, P.J., Martinez Jimenez, M., Yang, C., Canavan, K., Paynter, Q., Ota, N., Kriticos, D. 2023. Biology of invasive plants 4. Arundo donax L. Invasive Plant Science and Management. 16(2):81-109. https://doi.org/10.1017/inp.2023.17.
Goolsby, J., Maestas, L.P., Garcia III, R., May, M.A., Lohmeyer, K.H., Picanso, J., Anderson, D., Coy, J., Bonilla, D. 2023. Preventative methods to reduce the spread of cattle fever ticks on wildlife and protect local endangered species in South Texas. Southwestern Entomologist. https://doi.org/10.3958/059.048.0201.
Morales Ramos, J.A., Goolsby, J., Geden, C.J., Rojas, M.G., Garcia-Cancino, M.D., Rodriguez-Velez, B., Arredondo-Bernal, H., Ciomperlik, M.A., Simmons, G.S., Gould, J.R., Hoelmer, K.A. 2022. Production of hymenopteran parasitoids. In: Morales-Ramos, J.A., Rojas, M.G., Shapiro-Ilan, D.I., editors. Mass Production of Beneficial Organisms: Invertebrates and Entomopathogens. 2nd edition. San Diego, CA: Academic Press. p. 101-155.
Moran, P.J., Goolsby, J. 2022. Biological control of arundo, an invasive grass threatening water resources and national security. In: Van Driesche, R.G., Winston, R.L., Perring, T.M., Lopez, V.M., editors. Contributions of Classical Biocontrol to the U.S. Food Security, Forestry, and Biodiversity. FHAAST-2019-05. Morgantown, WV: USDA Forest Service. p. 373-389. https://bugwoodcloud.org/resource/files/23194.
Gaskin, J.F., Goolsby, J., Bon, M., Calatayud, P., Cristofaro, M. 2022. Identifying the geographic origins of invasive Megathyrsus maximus in the United States using molecular data. Invasive Plant Science and Management. 15(2):67-71. https://doi.org/10.1017/inp.2022.7.
Lafoe, G., Goolsby, J., Racelis, A., Butler, K., Rumpff, L., Hauser, C.E. 2023. Predicting the realised host-range of Leptinotarsa texana with open-field experiments. Biocontrol Science and Technology. https://doi.org/10.1080/09583157.2023.2229970.
Bon, M., Goolsby, J., Mercadier, G., Guermache, F., Kashefi, J., Cristofaro, M., Vacek, A., Kirk, A. 2023. The so-called ambrosia of the Arundo leaf miner, Lasioptera donacis, harbors a diverse endophytic fungal assemblage. Diversity. 15(4). Article 571. https://doi.org/10.3390/d15040571.
Zoromski, L.D., Deyoung, R.W., Goolsby, J., Foley, A., Ortega, J.S., Hewitt, D., Campbell, T. 2022. Fence line ecology: animal use of fence crossings in Southwestern rangelands. Ecology and Evolution. https://doi.org/10.1002/ece3.9376.
Moran, P.J., De Clerck-Floate, R., Hill, M.P., Raghu, S., Paynter, Q., Goolsby, J. 2022. Mass-production of arthropods for biological control of weeds: A global perspective. In: Morales-Ramos, J.A., Rojas, M.G., Shopiro-Ilan, D.I., editors. Mass Production of Beneficial Organisms. 2nd edition. London, UK: Academic Press. p. 157-194.
Baumgardt, J.A., Foley, A.M., Sliwa, K.M., Deyoung, R.W., Ortega S., A.J., Hewitt, D.G., Campbell, T.A., Goolsby, J., Lohmeyer, K.H. 2023. Effect of helicopter net gunning on the survival and movement behaviour of nilgai antelope. Wildlife Research. DOI: 10.1071/WR22049.
Goolsby, J., Hoelmer, K.A., Gould, J. 2022. Classical Biological Control of Silverleaf Whitefly in the United States. In: Driesche, R.G van, Winston, R.L., Perring, T.M., Lopez, V.M., editors. Contributions of Classical Biological Control to the U.S. Food Security, Forestry, and Biodiversity. West Virginia: USDA Forest Service. p. 59-72.