Progress 10/01/23 to 09/30/24
Outputs
PROGRESS REPORT Objectives (from AD-416): 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 (from AD-416): 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. Objective 1: Research efforts to develop population genetic and ecological methods to improve cattle fever tick (CFT) surveillance were conducted over the life of this project. Studies in collaboration with scientists at the Pathogen and Microbiome Institute, Northern Arizona University, focused on integrating CFT genetic data with geographic information system (GIS) tools to enhance understanding of the geographic source and population structure of CFT causing outbreaks. The resulting sequence variations that are associated with CFT resistance to permethrin as well as sequence variations that can be used to compare CFT populations within and between U.S. and Mexico are now generated year- round as outbreaks occur. This critical information is used by the USDA- APHIS-VS Cattle Fever Tick Eradication Program (CFTEP) and the Texas Animal Health Commission (TAHC) in support of their programmatic CFT eradication efforts. To 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 is being utilized by the CFTEP with over 100 CFTEP field inspectors in eight different county work areas using the tool for real-time entry of CFT infestation data. CFTEP inspectors in the field can 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 drastically decreased data entry workflow, enabled rapid identification of at-risk areas in south Texas, and allowed for faster programmatic decision making. ARS researchers also maintain a decades old geographic information system (GIS) database that tracks and archives CFT infestation location and collection data from cattle, equine, and wildlife hosts. This GIS database is used by ARS researchers and the CFTEP to inform operational decisions inside and outside of the Permanent Quarantine Zone (PQZ) in south Texas. Population models that explore the impacts of host, host habitat use, and eradication practices on CFT population dynamics were developed during this 5-year project. Eradication efforts by the CFTEP along the U.S.- Mexico border in south Texas are complicated by the involvement of wildlife hosts including white-tailed deer and nilgai antelope. ARS scientists in Kerrville, Texas, in collaboration with partners at Texas A&M University, developed two CFT population models that explored infestation scenarios. The first model assessed the potential effects of host species composition and host habitat use patterns on CFT infestations and assessed the risk for CFT infestations across the landscape in the PQZ. The second model investigated the potential role of nilgai in sustaining CFT populations by simulating infestation and eradication scenarios. The developed models generate near-real-time infestation forecasts that can be used to predict and prevent wildlife impacts on CFT eradication efforts. In further support of this objective, ARS researchers in Edinburg, Texas evaluated several methods to mechanically collect larval CFT from the environment including the ⿿tick-vac and the ⿿tick bot. Field studies were conducted in naturally infested CFT habitats to compare these two collection methods to the previously tested ⿿tick trouser method. Additionally, two other novel tick sampling methods, sampling bovine feces for detection of biochemicals as an indicator of tick infestation and using Raman spectroscopy to sample for tick fecal residues on cattle, were developed and tested in collaboration with Texas A&M University. These methods are effective, non-invasive, and non-destructive technologies to detect tick infestations. Objective 2. ARS researchers in Edinburg and Kerrville, Texas, developed novel methods to control CFT that utilize biocontrol strategies, botanical compounds, and novel acaricides. Acaricides are an important tool for use in mitigating CFT world-wide. Novel long-acting acaricide formulations are continuously needed to reduce the number of systematic treatments needed to manage CFT infestations. Barn trials with stanchioned cattle were continued as part of an ongoing collaboration with an animal health industry partner to evaluate the therapeutic and residual efficacy of a pour-on formulation of fluralaner for controlling CFT, Amblyomma americanum, and A. mixtum infesting cattle. Additionally, pasture studies were conducted in collaboration with Texas A&M University to evaluate the control efficacy of novel dosing regimens of macrocyclic lactones (doramectin, eprinomectin, and moxidectin) against CFT as well as the synergistic effect of combining these acaricides with the Bm86 vaccine. Studies are currently underway to further evaluate the efficacy of two injectable eprinomectin repeated dosing regimens for use by the CFTEP and TAHC to control CFT. Alternatives to traditional acaricides are also needed for use in the CFTEP, in particular as concerns about acaricide resistance and overuse increase. Researchers in Kerrville and Edinburg, Texas, evaluated natural botanicals, abrasives, and desiccants against CFT for use in sensitive wildlife areas. In vivo and in vitro studies were completed 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 is underway. Throughout this project, remotely operated nematode sprayers were evaluated as a non-chemical control option for CFT. ARS scientists in Edinburg, Texas, worked closely with the Animal and Plant Health Inspection Service-Veterinary Services and ranchers in south Texas to conduct large-scale field tests of a nematode sprayer to eradicate CFT on free-ranging nilgai antelope. More than 100 sprayers were deployed over 5000 acres to apply entomopathogenic nematodes (Nemasys-R, BASF Co.) as the nilgai transited through fence crossings. Numbers of cattle fever ticks on nilgai were found to be significantly lower on nilgai at treated vs. untreated control ranches. This technology has been transferred to the CFTEP and will be utilized to treat nilgai and white-tailed deer within the PQZ. Additionally, remotely activated sprayers were utilized in a field study in Cameron County, Texas, to evaluate whether use of the sprayers at corn feeders impacted white-tailed deer use of the feeders. Camera observations indicated that use of the sprayers at the feeders, either only spraying water or the botanical pesticide Stop the Bites®, did not deter the deer from using the feeders indicating that remotely activated sprayers may be operationally feasible for use by the CFTEP for treating deer in south Texas. Additionally, a commercially built, remotely operated 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 infested cattle or wildlife as they approach water troughs or fence gaps. In a continued effort to track and mitigate acaricide resistance, ARS researchers in Edinburg, Texas, continually process incoming live CFT samples from outbreak premises in south Texas. Incoming 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 is measured and reported weekly to CFTEP 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 (in support of Objective 1). In further support of this objective, ARS researchers in collaboration with international partners in Vietnam, Bulgaria, and Greece, developed and tested methods to collect Ixodiphagous parasitoid wasps using cattle infested with Rhipicephalus spp. ticks, including CFT. Preliminary DNA evidence indicates that Ixodiphagus wasps do parasitize Rhipicephalus spp. tick in Vietnam. Tick exposures were conducted in northern Vietnam and potentially parasitized Rhipicephalus spp. ticks, including CFT, were collected and kept alive or put into ethanol for emergence of the parasitoid for molecular screening. Live-exposed larvae, nymphs, and adults were brought back to the U.S. for visual analyses and molecular screening. Initial molecular screening detected the presence of Ixodiphagus parasitoids and emerged parasitoids have successfully been collected from the closely related species R. sanguineus. Additional CFT collections are planned in Vietnam to maximize the possibility of collecting parasitized CFT. Discovery and establishment of a specialist parasitoid for CFT could have significant impacts and enhance the efficiency and sustainability of the CFTEP in the transboundary region between Texas and Mexico. ACCOMPLISHMENTS 01 Nilgai antelope are not susceptible to infection with a virulent strain of Babesia bovis. Cattle fever ticks (CFT) transmit bovine babesiosis (BB) to cattle. This protozoal parasite can cause mortality rates up to 90% in previously unexposed cattle. In south Texas, CFT readily infest Nilgai in addition to cattle; however, their susceptibility to infection with BB is unknown. ARS researchers in Kerrville, Texas, in collaboration with Texas A&M University demonstrated that Nilgai do not display clinical signs of infection after inoculation with the merozoite or sporozoite stage of BB. This finding indicates that although Nilgai play an important role in the dissemination of CFT in south Texas, they do not play a significant role in the epidemiology of BB in south Texas. 02 Organic alternatives for cattle fever tick control. The cattle fever tick (CFT) is the most economically important tick worldwide. Traditional management of this tick depends on synthetic acaricides; however, the emergence of resistance has resulted in a need for novel compounds. ARS researchers in collaboration with Texas A&M University evaluated the efficacy of five organic compounds (nootkatone, Stop the Bites®, BioUD®, lavender oil, and cedarwood oil) for controlling CFT. Results indicate that NootkaShield, Stop the Bites, and BioUD led to significant CFT mortality at low concentrations, had strong repellent properties, and significantly impacted CFT fecundity. These organic compounds show great potential for use as alternatives to synthetic acaricides for controlling CFT. 03 Off-host longevity of cattle fever ticks in south Texas. As part of the U.S. program to eradicate cattle fever ticks (CFT) Rhipicephalus (Boophilus) annulatus (RA) and R. (B). microplus (RM), from south Texas, premises infested with CFT are subject to regulatory oversight that includes acaricide treatment and pasture vacation. Current pasture vacation duration time is based on tick degree-day data far from south Texas. ARS researchers in Edinburg, Texas, in collaboration with Texas A&M University assessed the impact of thermal stress on the longevity of RA and RM larvae in south Texas pastures. Results demonstrated that RA can survive in the pasture for 142 days in shady habitat in the winter and 130 days in the summer. RM can survive in winter for 113 days in the shade and 103 days in exposed habitat. These results indicate that temperature is a key variable in off-host survival of RA, but not RM. These results suggest that a reduction in the Texas pasture vacation period from 9 to 6 months would be justified for RM, giving cattle producers additional time to access pastures for grazing. 04 South Texas nematodes control cattle fever ticks. Entomopathogenic nematodes are roundworms that parasitize and kill arthropods. ARS researchers in Edinburg, Texas, and Poplarville, Mississippi, evaluated the control efficacy of an entomopathogenic nematode from south Texas, Steinernema riobrave, for controlling larval cattle fever ticks (CFT). Weekly applications of in vitro-reared S. riobrave (BASF- Nemasys-R) sprayed on CFT-infested potted buffelgrass killed significantly more larval ticks than water or the no treatment check. Use of a native nematode species like S. riobrave that occurs in the south Texas environment and has few effects on native plants and animals may be an environmentally friendly option for mitigating CFT in the environment, especially in areas inhabited by threatened or endangered species.
Impacts
(N/A)
Publications
- Schoville, S.D., Dong, D., Paskewitz, S., Maestas, L.P., Tsao, J., Burke, R.L., Ginsberg, H. 2024. Genome resequencing reveals population divergence and local adaptation of blacklegged ticks in the United States. Molecular Ecology. https://doi.org/10.1111/mec.17460.
- Goolsby, J., Maestas, L.P., Adamczyk Jr, J.J. 2024. Evaluation of the efficacy of Steinernema riobrave against Rhipicephalus microplus larvae at semi-field conditions. Southwestern Entomologist. https://doi.org/10.3958/ 059.049.0116.
- Thomas, D.B., Gaff, H., Leal Galvan, B. 2023. Mechanical devices for census and detection of off-host larval ticks (Acari: Ixodidae) with emphasis on the cattle fever tick. Subtropical Agriculture and Environments. 74:13-20.
- Arocho, C., Leal, B., Thomas, D.B. 2023. Degree-days and off host longevity of cattle fever ticks, Boophilus spp. (Acari: Ixodidae) in south Texas pastures. Journal of Economic Entomology. https://doi.org/10.1093/ jee/toad237.
- Johnson, T.L., Persinger, K.A., Taus, N.S., Davis, S.K., Poh, K.C., Kappmeyer, L.S., Laughery, J.M., Capelli-Peixoto, J., Lohmeyer, K.H., Ueti, M.W., Olafson, P.U. 2024. Nilgai antelope display no signs of infection upon experimental challenge with a virulent Babesia bovis strain. Parasites & Vectors. 17. Article 245.. https://doi.org/10.1186/s13071-024- 06316-3.
- Casey, T., Shifflett, S.A., Kennedy, A., Maestas, L.P., Ellis, V.A. 2024. Similar microbiome compositions of nymphal black-legged ticks (Ixodes scapularis) infected and uninfected with Borrelia burgdorferi in Delaware. Parasitology Research. https://doi.org/10.1016/j.ttbdis.2023.102139.
- Showler, A. 2023. Interactions of gulf cordgrass, Spartina spartinae (Trin. ) Merr. ex Hitchc., habitat with ixodids on the South Texas coastal plain. Environmental Entomology. https://doi.org/10.1186/s40068-023-00311-w.
- Oliva Chavez, A. S., S. Guzman Valencia, G. E. Lynn, C. A. Rosario, D. B. Thomas, and T. L. Johnson. 2023. Evaluation of the in vitro acaricidal effect of five organic compounds on the cattle fever tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae). Exp Appl Acarol 89: 447-460.
- Goolsby, J., Maestas, L.P., Garcia Iii, R., Cruz, M., Feria, T. 2024. Nilgai, Boselaphus tragocamelus and white-tailed deer, Odocoileus virginianus use of water troughs with and without remotely operated field sprayers for potential treatment of cattle fever ticks. Subtropical Agriculture and Environments. 74:21-25.
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Progress 10/01/22 to 09/30/23
Outputs
PROGRESS REPORT Objectives (from AD-416): 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 (from AD-416): 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. 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 01 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. 02 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. 03 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.
Impacts
(N/A)
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.
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Progress 10/01/21 to 09/30/22
Outputs
PROGRESS REPORT Objectives (from AD-416): 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 (from AD-416): 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. In support of Subobjective 1A, integrate cattle fever tick genetic data with geographic information system (GIS) tools to enhance understanding of the geographic source and population structure of ticks causing outbreaks, ARS scientists have continued collaborative efforts with scientists at The Pathogen and Microbiome Institute, Northern Arizona University, to assess presence of sequence variations associated with cattle fever tick resistance to permethrin as well as sequence variations that are informative for distinguishing geographically separated populations of cattle fever ticks. Results are routinely provided to the USDA-APHIS-VS Cattle Fever Tick Eradication Program (CFTEP) in support of programmatic efforts. In addition, ARS scientists and collaborators are using next-gen sequencing approaches to potentially increase the number of informative sequence variations that can be used when comparing cattle fever tick populations within and between U.S. and Mexico isolates. Tick samples have been identified for pooling, library construction, and sequencing on the Illumina platform. In support of Subobjective 1B, enhance GIS-based tools for cattle fever tick surveillance, ARS researchers partnered with the ARS Partnerships for Data Innovations (PDI) team to develop a FieldMaps tool for the CFTEP to streamline data entry and enable real-time access to the fever tick infestation database. This FieldMaps tool was initially beta tested by select CFTEP field inspectors and has now been officially launched for use by the eradication program. Over 100 CFTEP field inspectors in eight different county work areas have access to this tool for real-time entry of fever tick infestation data. This new system allows CFTEP inspectors in the field to record fever tick outbreak data from their phones directly to an online map layer that can be quickly 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 1C, develop novel and refine existing cattle fever tick sampling methods, ARS researchers evaluated several methods to mechanically collect fever ticks from the environment including the ⿿tick-vac and the ⿿tick bot. Field studies were conducted in naturally infested fever tick habitats to compare these two collection methods to the previously tested ⿿tick trouser method. Additionally, two other novel tick sampling methods, 1- sampling bovine feces for detection of biochemicals as an indicator of tick infestation and 2-using Raman spectroscopy to sample for tick fecal residues on cattle, were developed and tested in collaboration with Texas A&M University. Both methods show promise for use as a non-invasive, non- destructive method for detecting tick infestations. In support of Subobjective 2A, refine the remotely activated sprayer to treat cattle fever tick infestations in nilgai and white-tailed deer, ARS researchers evaluated the efficacy of Barricade® fire gel as a UV protectant to extend the life of entomopathogenic nematodes that are utilized in a spray in the remotely activated sprayers for controlling cattle fever ticks on wildlife. Studies indicated that Barricade® has the potential to improve the efficacy of Steinernema riobrave and Heterorhabditis floridensis, two nematodes that kill cattle fever ticks, by reducing mortality and desiccation. Additionally, remotely activated sprayers were utilized in a field study in Cameron County to evaluate whether use of the sprayers at corn feeders impacted white-tailed deer use of the feeders. Camera observations indicated that use of the sprayers at the feeders, either only spraying water or the botanical pesticide Stop the Bites®, did not deter the deer from using the feeders. These results suggest that use of remotely activated sprayers for the treatment of fever ticks on deer that utilize corn feeders may be operationally feasible for use by the CFTEP in south Texas. In support of Subojective 2C, evaluate natural botanicals, abrasives, and dessicants against cattle fever ticks for use in sensitive wildlife areas, in vivo and in vitro studies were continued to evaluate the efficacy of desiccant dusts and botanical products (nootkatone, cedar oil, and Stop the Bites®) for controlling lone star and cattle fever ticks. In support of Subjective 2D, discover and evaluate classical biological control agents for CFT, ARS researchers developed and tested methods to collect Ixodiphagous parasitoid wasps using cattle fever tick infested cattle in the tick⿿s native range including Vietnam, Bulgaria, and Greece. To date no Ixodiphagus wasp have been conclusively reared from fever tick nymphs, but studies are underway to expose fever tick larvae in Vietnam to determine if this off-host life stage is parasitized. Preliminary DNA evidence indicates that Ixodiphagus wasps do parasitize fever tick larvae. Discovery and establishment of a specialist parasitoid for cattle fever ticks could have significant impacts and enhance the efficiency and sustainability of the CFTEP in the transboundary region between Texas and Mexico and worldwide where cattle fever ticks are invasive. 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, protocols were developed and approved to evaluate the therapeutic and residual efficacy of a pour-on formulation of fluralaner for controlling Amblyomma mixtum and cattle fever ticks infesting cattle. Pasture studies to evaluate varying doses of macrocyclic lactones (doramectin, eprinomectin, and moxidectin) for fever tick control were completed and tick efficacy and pharmacokinetic data are being 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. ACCOMPLISHMENTS 01 Tick identification using spectroscopic analysis of feces. Ticks are blood-feeding parasites that vector pathogens of medical and veterinary importance and cause billions of dollars in economic losses globally each year. New methods for early detection of ticks, in particular exotic or invasive species, are needed. Timely detection of tick species on hosts like cattle can cease the spread of devastating diseases like babesiosis and anaplasmosis. ARS researchers in Edinburg, Texas in collaboration with Texas A&M University, found that Raman spectroscopy can be used as a non-invasive, non-destructive method to identify ticks by their feces. Further development of this surveillance method could lead to faster detection of exotic or invasive tick species or significantly reduce the time and cost of inspecting livestock as part of a tick management or eradication program. 02 Cattle fecal chemistry changes with tick development. Cattle fever ticks are a globally important ectoparasite of cattle and are known to harbor pathogens that can cause diseases in cattle like cattle fever and anaplasmosis. Detection of cattle fever ticks on cattle is a critical component of the south Texas based Cattle Fever Tick Eradication Program. Current detection practices include restraining cattle and inspecting the hair coat of each animal individually by hand. ARS researchers in Edinburg, Texas and Parlier, California, in collaboration with Texas A&M University, found near infrared reflectance spectroscopy (NIRS) could be used to detect fecal chemistry changes in cattle that had been infested with fever ticks. This finding indicates that NIRS analysis of cattle feces could be utilized for detecting cattle fever ticks infesting cattle in south Texas without having to restrain cattle or inspect each animal by hand, saving valuable time and resources. 03 Cattle fever tick interactive database developed. The Cattle Fever Tick Eradication Program (CFTEP) is a collaborative effort among state and federal agencies, including USDA, Animal and Plant Health Inspection Service (APHIS), ARS, and the Texas Animal Health Commission. Fever tick quarantine regulations are enforced along 500 miles of the Rio Grande River border with Mexico to prevent fever ticks carrying disease pathogens from entering the United States. With the help of ARS, the CFTEP maintains land ownership records, fenceline locations, and tick inspection data for this area. Compiling this data into a format that fever tick researchers and CFTEP personnel can easily access is time consuming and involves input of over 3000 datapoints per month. To better streamline this process, ARS researchers in Kerrville, Texas partnered with the ARS Partnerships for Data Innovations team to develop a new data entry platform that utilizes the FieldMaps tool by Esri. This new phone-based data entry system allows CFTEP inspectors in the field to record fever tick outbreak data directly to an online map layer that program personnel and ARS researchers can access in real time leading to faster analysis of tick outbreaks and identification of at-risk areas.
Impacts
(N/A)
Publications
- Osbrink, W.L., Thomas, D.B., Lohmeyer, K.H., Temeyer, K.B. 2021. Climate change and alternative hosts complicate the eradication of cattle fever ticks (Acari: Ixodidae) in the southern United States, a review. Annals of the Entomological Society of America. 20. https://doi.org/10.1093/aesa/ saab034.
- Showler, A., Shah, S., Sulaiman, Khan, S., Ullah, S., Sadaf, Degola, F. 2022. Desert locust episode in Pakistan 2018-2021 and the current status of integrated desert locust management. Journal of Integrated Pest Management. 13. https://doi.org/10.1093/jipm/pmab036.
- Kutugata, M.D., Goolsby, J., Baumgardt, J.A., Racelis, A. 2021. Automatic camera trap classification using wildlife-specific transfer learning in nilgai management. Journal of Fish and Wildlife Management. https://doi. org/10.3996/JFWM-20-076.
- Shapiro Ilan, D.I., Goolsby, J. 2021. Evaluation of Barricade® to enhance survival entomopathogenic nematodes on cowhide. Journal of Invertebrate Pathology. 184. https://doi.org/10.1016/J.JIP.2021.107592.
- Leal-Galvan, B., Harvey, C., Oliva Chavez, A., Thomas, D.B., Saelao, P. 2022. A method for the isolation of miRNAs from tick ex vivo salivary gland cultures and extracellular vesicles. The Journal of Visualized Experiments (JoVE). https://doi.org/10.3791/63618.
- Klafke, G., Thomas, D.B., Miller, R., Perez De Leon, A.A. 2021. Efficacy of water-based botanical acaricide formulation applied in portable spray box against the fever tick, Rhipicephalus (Boophilus) microplus (Acari: Ixodidae), infesting cattle. Veterinary Parasitology. 12. Article 101721. https://doi.org/10.1016/j.ttbdis.2021.101721.
- Suderman, M.T., Temeyer, K.B., Schlechte, K.G., Perez De Leon, A.A. 2021. Three-dimensional culture of Rhipicephalus (Boophilus) microplus BmVIII- SCC cells on multiple synthetic scaffold systems and in rotating bioreactors. Insects. 12. Article 747. https://doi.org/10.3390/ insects12080747.
- Lohmeyer, K.H. 2021. Highlights in Veterinary Entomology, 2020: The Importance of the Contributions of Government Scientists to Research in Veterinary Entomology. Medical Entomology. https://doi.org/10.1093/jme/ tjab104.
- Wulff, J.P., Temeyer, K.B., Tidwell, J.P., Schlechte, K.G., Lohmeyer, K.H., Pietrantonio, P.V. 2022. Pyrokinin receptor silencing in females of the southern cattle tick Rhipicephalus (Boophilus) microplus is associated with a reproductive fitness cost. Parasites & Vectors. https://doi.org/10. 1186/s13071-022-05349-w.
- Poh, K.C., Evans, J.R., Michael, S.J., Olafson, P.U., Hickling, G., Mullinax, J., Machtinger, E.T. 2022. Patterns of deer ked (Diptera: Hippoboscidae) and tick (Ixodida: Ixodidae) infestation on white-tailed deer (Odocoileus virginianus) in the eastern United States. Parasites & Vectors. 15. Article 31. https://doi.org/10.1186/s13071-021-05148-9.
- Goolsby, J., Maestas, L.P., Saelao, P., Lohmeyer, K.H. 2022. Evaluation of the repellency of Stop the Bites® botanical acaricide to white-tailed deer at corn feeders. Southwestern Entomologist. https://doi.org/10.3958/059. 047.0202.
- Rich, B., Thomas, D.B., Longnecker, M., Tolleson, D., Angerer, J.P., Perez de Leon, A.A., Teel, P. 2022. Bovine fecal chemistry changes with progression of Southern Cattle Tick, Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) infestation. Veterinary Parasitology. https://doi.org/10. 1016/j.vetpar.2022.109679.
- Zoromski, L.D., Deyoung, R.W., Goolsby, J., Foley, A., Ortega-S, J.A., Hewitt, D., Campbell, T. 2022. Latrine ecology of nilgai antelope. Journal of Mammalogy. https://doi.org/10.1093/jmammal/gyac056.
- Dou, T., Ermolenkov, A., Hays, S., Rich, B., Donaldson, T., Thomas, D.B., Teel, P., Kurouski, D. 2022. Raman-based identification of tick species (Ixodidae) by spectroscopic analysis of their feces. Analytical Chemistry. https://doi.org/10.1016/j.saa.2022.120966.
- Thomas, D.B., Duhaime, R. 2022. Medicated Corn Feeders to Disinfest Cattle Fever Ticks (Boophilus: Ixodidae: Acari) in a Suburban Population of White- Tailed Deer. Experimental and Applied Acarology. https://doi.org/10.1007/ s10493-022-00699-7.
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Progress 10/01/20 to 09/30/21
Outputs
PROGRESS REPORT Objectives (from AD-416): Objective 1: Determine variables that influence tick range, suitable tick habitats, risk of tick-borne disease outbreaks, and potential for introduction of invasive ticks. Objective 2: Develop population genetic, ecological, and computational methods to improve cattle fever tick surveillance. Subobjective 2A: Integrate cattle fever tick (CFT) genetic data with geographic information system (GIS) tools to enhance understanding of the geographic source and population structure of ticks causing outbreaks. Subobjective 2B: Enhance GIS-based tools for CFT surveillance. Subobjective 2C: Develop novel, and refine existing, CFT sampling methods. Subobjective 2D: Model tick habitat suitability using machine/deep learning to predict favorable cattle fever tick locations in South Texas and Puerto Rico. Objective 3: Develop methods to control cattle fever ticks on livestock including new vaccines, genetic approaches, and other approaches to mitigate acaricide resistance. Subobjective 3A: Evaluate the efficacy of novel acaricides and delivery systems against ticks on livestock, and through the targeted treatment of infested pastures and protected and sensitive habitats. Subobjective 3B: Identify candidate antigens for anti-tick vaccines and formulate as vaccines for animal trials. Subobjective 3C: Compare the genomes of R. microplus, R. annulatus, and Haemaphysalis longicornis to identify sex determination genes for the development of genetic control methods. Subobjective 3D: Evaluate novel long-acting (LA) acaricide formulations to reduce the number of systematic treatments needed to manage cattle fever tick infestations. Subobjective 3E: Define the role of genetics in the immunobiology of cattle-tick interactions to develop effective immunogenetics-based strategies to protect cattle from ticks and tick-borne diseases. Objective 4: Develop methods to mitigate the impact of invasive and exotic ticks. Subobjective 4A: Determine genetic differences between H. longicornis populations from the U.S., and its native and invaded range through comparative molecular studies. Subobjective 4B: Characterize genes known to be associated with resistance to commonly used acaricides in invasive and exotic tick species. Objective 5: Develop methods to control cattle fever ticks on wildlife, including anti-tick vaccine delivery, ecologically-friendly compounds, chemical delivery mechanisms and biological control organisms. Component 1: Problem Statement 1A Subobjective 5A: Refine the remotely-activated sprayer to treat CFT infestation in nilgai and white-tailed deer. Subobjective 5B: Evaluate delivery of anti-tick vaccines for use in white-tailed deer and nilgai. Subobjective 5C: Evaluate natural botanicals, abrasives, and desiccants against cattle fever tick for use in sensitive wildlife habitats. Subobjective 5D: Discover and evaluate classical biological control agents for cattle fever tick. Approach (from AD-416): 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. In support of Objective 1, to determine variables that influence tick range, suitable tick habitats, risk of tick-borne disease outbreaks, and potential for introduction of invasive ticks, a database was developed describing live ticks collected on white-tailed deer and nilgai hosts. These hosts were harvested during public hunts on a national wildlife refuge site. Tick species on each host was recorded and individual specimens were used in molecular assays to identify pathogens harbored by the various ticks. The tropical horse tick predominated the collections, and Gulf Coast tick, blacklegged tick, and inornate tick specimens were also identified. Tick-borne piroplasms and bacteria were detected in specimens, including Theileria cervi, Rickettsia parkeri, Anaplasma sp, and Ehrlichia sp. This provides valuable information about the tick species that overlap in habitat with cattle fever ticks and about pathogens that are circulating in this southern Texas environment. In support of Objective 2, deploy data visualization tools, including geographic information system (GIS)-based tools for cattle fever tick (CFT) surveillance, the GIS database incorporating location, collection, and infestation records for fever ticks infesting cattle, white-tailed deer, and nilgai continued to be updated regularly. This GIS database is used by the Cattle Fever Tick Eradication Program to inform operational decisions inside and outside of the Permanent Quarantine Zone in South Texas. Additionally, in collaboration with ARS partners a prototype was developed of a web mapping application combined with data collection via Collector and Survey123 Apps. This application will streamline spatial data collection, editing, and dissemination tasks in the field when a tick outbreak is discovered removing the potential for data errors and lag times in data collection and distribution. Access to the web map application in the field will allow tick inspectors to verify their location with landowners immediately with a selected premise and visualize data that pertains to program management and planning. In support of Objective 3, continued development of new tick control technology, the efficacy of novel acaricides and delivery systems were evaluated against ticks on livestock. Diatomaceous earth and silica gel augmented with botanical pyrethrins or thyme oil were determined to be highly effective against immature ixodid ticks. Additionally, silica gel and silica gel + pyrethrins, were evaluated for controlling immature ticks feeding on cattle. The nonaugmented silica gel prophylactically protected cattle from tick feeding, but it did not kill ticks that were already attached to the host and imbibing blood. The pyrethrin-augmented silica gel provided prophylactic protection as well as controlling ticks engaged in feeding. Potential genetic targets for tick control can be validated through gene silencing using RNAi. RNA interference (RNAi) was utilized to silence gene expression in tick cell culture and in live ticks. RNAi identified as acaricidal when microinjected into southern cattle fever ticks was commercially prepared and utilized to develop a qRT-PCR assay to quantitate RNAi presence in bovine blood, including use of a control dsRNA utilized to spike bovine blood samples to control and quantitate RNA recovery. RNAi silencing of the R. microplus pyrokinin receptor and another GPCR (G-protein coupled receptor) protein was completed. Refine the remotely activated sprayer to treat CFT infestation in nilgai and white-tailed deer. A large-scale field test of remotely operated sprayers to eradicate CFT on free-ranging nilgai antelope was repeated. More than 100 sprayers were deployed to apply locally native nematodes that kill CFT as the nilgai passed through fence crossings at private ranches in South Texas. Numbers of CFT on treated nilgai were significantly lower again for the second year. Compare the genomes of R. microplus, R. annulatus, and Haemaphysalis longicornis to identify sex determination genes for the development of genetic control methods. Utilizing the genomes of the southern cattle tick, R. microplus, and the Asian longhorned tick, H. longicornis, candidate genes associated with sex determination found in R. annulatus were compared to those found in H. longicornis. Highly conserved genes were gathered that may play a role in the sex determination of H. longicornis that shows orthology to R. annulatus. Novel long-acting (LA) acaricide formulations will reduce the number of systematic treatments needed to manage CFT infestations. Collaboration with the animal health industry on the research and development of safe LA acaricide formulations that could be used to treat cattle for the eradication of fever ticks continued. In support of Objective 4A, determine genetic differences between H. longicornis populations from the U.S. and its native and invaded range using comparative molecular studies, next generation sequencing was utilized to identify unique sequence differences between individual Asian longhorned ticks originating from the northeastern U.S. These sequence differences can now be used to compare populations of the Asian longhorned tick from other regions of the U.S. This provides an opportunity to understand population relatedness of this invasive species. In support of Objective 4B, characterize genes known to be associated with resistance to commonly used acaricides in invasive and exotic tick species, research continued in support of efforts by the Cattle Fever Tick Eradication Program to understand the development of acaricide resistance in outbreak strands of CFT in south Texas. A single mutation was discovered that provides acetylcholinesterase resistance to the acaricide coumaphos. Additional polymorphisms were expressed as recombinant proteins that indicate that combinations of acetylcholinesterase mutations may play a role in organophosphate resistance. Record of Any Impact of Maximized Teleworking Requirement: Maximized telework due to ongoing COVID-19 pandemic limited our ability to conduct laboratory and field research. Maximized teleworking did enable researchers to make progress on analyzing a backlog of existing data and prepare manuscripts. ACCOMPLISHMENTS 01 Sequence and assembly of Rhipicephalus microplus and Rhipicephalus annulatus genome data. Ticks from the genus Rhipicephalus have global economic impact as ectoparasites of cattle. These ticks are known to harbor pathogens that cause diseases in cattle like cattle fever and anaplasmosis. ARS scientists in Kerrville and Edinburg, Texas, collaborated with researchers from Texas A&M University, Prairie View A&M University, and Carnegie Mellon University to sequence and assemble the genomes of R. microplus and R. annulatus. Having reference quality genomes of these two species of cattle fever ticks will advance research to identify genetic targets for developing new vaccines or novel anti-tick compounds. 02 Tropical horse ticks from white-tailed deer harbor theileriosis parasite, a protozoan that can cause anemia and animal death. The border region of south Texas shares a tropical tick fauna with Mexico that is unlike that found in the rest of the U.S. Cattle fever ticks, vectors of cattle tick fever, occupy this landscape, but other tick species that inhabit this region are understudied, as are the parasites that may be harbored by these tick populations. ARS researchers in Kerrville and Edinburg, Texas, described tick species collected from white-tailed deer and nilgai antelope that were harvested during public hunts on a national wildlife refuge site. The tropical horse tick predominated the collections, and Gulf Coast tick, blacklegged tick, and inornate tick specimens were also identified. Larval, nymphal, and adult tropical horse ticks harbored a theileriosis parasite reported from white-tailed deer; this parasite is typically transmitted by the lone star tick, which was not encountered in the study region. This provides valuable information about the tick species that overlap in habitat with cattle fever ticks and about pathogens that are circulating in this southern Texas environment. 03 Remotely operated nematode sprayers provide non-chemical control of cattle fever ticks. Cattle fever ticks (CFT) threaten U.S. animal agriculture because they transmit the microbes that cause bovine babesiosis, a disease that causes rapid death in cattle. In south Texas, wildlife such as white-tailed deer and nilgai antelope serve as alternative hosts for CFT, complicating eradication efforts. A novel technology to treat wildlife infested with cattle fever ticks was successfully tested and shown to be effective. ARS scientists in Edinburg, Texas, worked closely with the Animal and Plant Health Inspection Service-Veterinary Services and ranchers in South Texas to conduct large-scale field tests of a nematode sprayer to eradicate CFT on free-ranging nilgai antelope. More than 100 sprayers were deployed over 5000 acres to apply entomopathogenic nematodes (Nemasys-R, BASF Co. ) as the nilgai transited through fence crossings. Numbers of cattle fever ticks on nilgai were significantly lower on nilgai at treated vs. untreated control ranches. 04 Population models explore the impacts of host, host habitat use, and eradication practices on cattle fever tick population dynamics. Cattle fever ticks (CFT) are vectors of bovine babesiosis and pose a threat to the U.S. livestock industry. Efforts by the Cattle Fever Tick Eradication Program (CFTEP) along the U.S.-Mexico border in south Texas are complicated by the involvement of wildlife hosts, including white- tailed deer and nilgai antelope. ARS scientists in Kerrville, Texas, in collaboration with partners at Texas A&M University, developed two CFT population models to explore the infestation scenarios. The first model assessed potential effects of host species composition and host habitat use patterns on CFT infestations and assessed the risk for CFT infestations across the landscape in the Permanent Quarantine Zone. The second model investigated the potential role of nilgai in sustaining CFT populations by simulating infestation and eradication scenarios. The developed models suggest: 1) integration of such data into these models will facilitate the development of new eradication strategies and will allow near-real-time infestation forecasts that can be used to predict and prevent wildlife impacts on CFT eradication efforts, and 2) infestations of CFT on nilgai add to populations of CFT larvae in the landscape and promote the persistence of CFT. The models develop the utility of enhanced biosurveillance using simulation tools to lessen risk and enhance area-wide tick management programs like the CFTEP.
Impacts
(N/A)
Publications
- Showler, A. 2021. Incidence and ramifications of armed conflict in countries with major desert locust breeding areas. Agronomy Journal. 11:114. https://doi.org/10.3390/agronomy11010114.
- Paim, E., Dias, A., Showler, A., Campos, K., Santos, P., Grilo, P., Torres, J., Bastos, C. 2021. Cotton row spacing for boll weevil management in low- input production systems. Crop Protection Journal. 145. https://doi.org/10. 1016/j.cropro.2021.105614.
- Halstead, M., Kern, C., Saelao, P., Wang, Y., Chanthavixay, G., Medrano, J. F., Van Eenennaam, A.L., Korf, I., Tuggle, C.K., Ernst, C.W., Zhou, H., Ross, P.J. 2020. A comparative analysis of chromatin accessibility in cattle, pig, and mouse tissues. BMC Genomics. 21:698. https://doi.org/10. 1186/s12864-020-07078-9.
- Vacek, A.T., Goolsby, J., Kariyat, R.R. 2020. Development and testing of artificial membranes for rearing of Rhipicephalus microplus, the southern cattle fever tick. Subtropical Agriculture and Environments. 71:59-66.
- Guerrero, F., Ghaffari, N., Bendele, K.G., Metz, R.P., Dickens, C.M., Blood, P.D., Tidwell, J.P., Miller, R., Perez De Leon, A.A., Teel, P.D., Johnson, C.D. 2021. Raw Pacific Biosciences and Illumina sequencing reads and assembled genome data for the cattle ticks Rhipicephalus microplus and Rhipicephalus annulatus. Data in Brief. 35. https://doi.org/10.1016/j.dib. 2021.106852.
- Tidwell, J.P., Trevino, D.E., Thomas, D.B., Mitchell III, R.D., Heerman, M. C., Perez De Leon, A.A., Lohmeyer, K.H. 2021. Pictorial dissection guide and internal anatomy of the southern Cattle Fever Tick, Rhipicephalus (Boophilus) microplus (Canestrini). Ticks and Tick Borne Diseases. 12. https://doi.org/10.1016/j.ttbdis.2021.101685.
- Romero-Salas, D., Solis-Cortes, M., Zazueta-Islas, H.M., Flores-Vasquez, F. , Cruz-Romero, A., Aguilar-Dominguez, M., Salguero-Romero, J.L., Perez De Leon, A.A., Fernandez-Figueroa, E.A., Lammoglia-Villagomez, M.A., Becker, I., Sanchez-Montes, S. 2021. Molecular detection of Theileria equi 1 in horses from Veracruz, Mexico. Ticks and Tick Borne Diseases. 12. https:// doi.org/10.1016/j.ttbdis.2021.101671.
- Arafa, W.M., Aboelhadid, S.M., Moawad, A., Shokeir, K.M., Ahmed, O.M., Perez De Leon, A.A. 2021. Control of Rhipicephalus annulatus resistant to deltamethrin by spraying infested cattle with synergistic eucalyptus essential oil-thymol-deltamethrin combination. Veterinary Parasitology. 290:109346. https://doi.org/10.1016/j.vetpar.2021.109346.
- Showler, A., Ebbe, M.O., Lecoq, M., Maeno, K.O. 2021. Early intervention against desert locusts: Current proactive approach and the prospect of sustainable outbreak prevention. Agronomy Journal. 11:312. https://doi.org/ 10.3390/agronomy11020312.
- Saelao, P., Hickner, P.V., Bendele, K.G., Perez De Leon, A.A. 2021. Phylogenomics of tick inward rectifier potassium channels and their potential as targets to innovate control technologies. Frontiers in Cellular and Infection Microbiology. 11. https://doi.org/10.3389/fcimb. 2021.647020.
- Olafson, P.U., Buckmeier, B.G., May, M.A., Thomas, D.B. 2021. Molecular screening for rickettsial bacteria and piroplasms in ixodid ticks collected from white-tailed deer and nilgai in south Texas. International Journal for Parasitology: Parasites and Wildlife. 13:252-269. https://doi. org/10.1016/j.ijppaw.2020.11.002.
- Machtinger, E.T., Springer, H.R., Brown, J.E., Olafson, P.U. 2021. Sudden mortality in captive white-tailed deer (Odocoileus virginianus) with atypical infestation of winter tick (Dermacentor albipictus). Journal of Medical Entomology. https://doi.org/10.1093/jme/tjab043.
- Wang, H., Grant, W.E., Teel, P.D., Lohmeyer, K.H., Perez De Leon, A.A. 2020. Enhanced biosurveillance of high-consequence invasive pests: southern cattle fever ticks, Rhipicephalus (Boophilus) microplus, on livestock and wildlife. Parasites & Vectors. https://doi.org/10.1186/ s13071-020-04366-x.
- Dos Santos, C., Guimaraes, D., Da Silva, L., Temeyer, K.B., Perez De Leon, A.A., Costa-Junior, L.M., Dos Santos, S. 2020. Terpenes on Rhipicephalus (Boophilus) microplus: Acaricidal activity and acetylcholinesterase inhibition. Veterinary Parasitology. 280. https://doi.org/10.1016/j.vetpar. 2020.109090.
- Wang, H., Grant, W.E., Teel, P.D., Lohmeyer, K.H., Perez De Leon, A.A. 2021. Simulated dynamics of southern cattle fever ticks (Rhipicephalus (Boophilus) microplus) in South Texas, USA: investigating potential wildlife impacts on cattle eradication. Parasites & Vectors. 14:231. https://doi.org/10.1186/s13071-021-04724-3.
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Progress 10/01/19 to 09/30/20
Outputs
Progress Report Objectives (from AD-416): Objective 1: Determine variables that influence tick range, suitable tick habitats, risk of tick-borne disease outbreaks, and potential for introduction of invasive ticks. Objective 2: Develop population genetic, ecological, and computational methods to improve cattle fever tick surveillance. � Subobjective 2A: Integrate cattle fever tick (CFT) genetic data with geographic information system (GIS) tools to enhance understanding of the geographic source and population structure of ticks causing outbreaks. � Subobjective 2B: Enhance GIS-based tools for CFT surveillance. � Subobjective 2C: Develop novel, and refine existing, CFT sampling methods. � Subobjective 2D: Model tick habitat suitability using machine/deep learning to predict favorable cattle fever tick locations in South Texas and Puerto Rico. Objective 3: Develop methods to control cattle fever ticks on livestock including new vaccines, genetic approaches, and other approaches to mitigate acaricide resistance. � Subobjective 3A: Evaluate the efficacy of novel acaricides and delivery systems against ticks on livestock, and through the targeted treatment of infested pastures and protected and sensitive habitats. � Subobjective 3B: Identify candidate antigens for anti-tick vaccines and formulate as vaccines for animal trials. � Subobjective 3C: Compare the genomes of R. microplus, R. annulatus, and Haemaphysalis longicornis to identify sex determination genes for the development of genetic control methods. � Subobjective 3D: Evaluate novel long-acting (LA) acaricide formulations to reduce the number of systematic treatments needed to manage cattle fever tick infestations. � Subobjective 3E: Define the role of genetics in the immunobiology of cattle-tick interactions to develop effective immunogenetics-based strategies to protect cattle from ticks and tick-borne diseases. Objective 4: Develop methods to mitigate the impact of invasive and exotic ticks. � Subobjective 4A: Determine genetic differences between H. longicornis populations from the U.S., and its native and invaded range through comparative molecular studies. � Subobjective 4B: Characterize genes known to be associated with resistance to commonly used acaricides in invasive and exotic tick species. Objective 5: Develop methods to control cattle fever ticks on wildlife, including anti-tick vaccine delivery, ecologically-friendly compounds, chemical delivery mechanisms and biological control organisms. Component 1: Problem Statement 1A � Subobjective 5A: Refine the remotely-activated sprayer to treat CFT infestation in nilgai and white-tailed deer. � Subobjective 5B: Evaluate delivery of anti-tick vaccines for use in white-tailed deer and nilgai. � Subobjective 5C: Evaluate natural botanicals, abrasives, and desiccants against cattle fever tick for use in sensitive wildlife habitats. � Subobjective 5D: Discover and evaluate classical biological control agents for cattle fever tick. Approach (from AD-416): 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. Objective 2. Deploy data visualization tools, including GIS-based tools for cattle fever tick (CFT) surveillance. The geographic information system (GIS) database incorporating location, collection, and infestation records for fever ticks infesting cattle, white-tailed deer, and nilgai continued to be updated regularly. This GIS database is used by the Cattle Fever Tick Eradication Program to inform operational decisions inside and outside of the Permanent Quarantine Zone in south Texas. Objective 3. Evaluate the efficacy of novel acaricides and delivery systems against ticks on livestock, and through the targeted treatment of infested pastures and protected and sensitive habitats. Research continued to develop new tick control technology and to mitigate acaricide resistance. RNA interference (RNAi) was utilized to silence gene expression in tick cell culture and in live ticks. Gene silencing in tick cell culture was used to assess double stranded (ds) RNA effectiveness. Selected dsRNAs were injected into live ticks to assess and validate the effects of silencing targeted genes on tick survival and reproduction. Other tick genes were also targeted using RNAi. Gene silencing by RNAi was observed to significantly increase tick mortality and/or decrease tick reproduction. Such observations validated these genes as targets for development of new tick control technology, potentially including anti-tick vaccines and novel acaricidal chemicals. Multiple tick genes were targeted simultaneously by constructing dsRNAs that combine sequences of different genes. These were evaluated by RNAi, and up to five molecular constructs exhibiting very high tick mortality were selected as candidates for direct RNAi-based tick control. Refine the remotely-activated sprayer to treat cattle fever tick infestation in nilgai and white-tailed deer. More than 100 sprayers were tested under field conditions in infested areas to treat nilgai moving through fence crossings with worms that kill fever ticks only. A second field study in underway to validate the preliminary results where the number of fever ticks was significantly lower in nilgai at treated vs. untreated field sites. Compare the genomes of R. microplus, R. annulatus, and Haemaphysalis longicornis to identify sex determination genes for the development of genetic control methods. The genome of the cattle fever tick Rhipicephalus annulatus was sequenced. This breakthrough allowed comparative genomic analyses with the southern cattle fever tick, R. microplus, and the Asian longhorned tick, H. longicornis. Access to the genetic blueprint of these invasive ticks will allow research and development of novel and safer control technologies. Novel long-acting (LA) acaricide formulations will reduce the number of systematic treatments needed to manage CFT infestations. Collaboration with the animal health industry on the research and development of safe LA acaricide formulations that could be used to treat cattle for the eradication of fever ticks continued. As part of this effort, a study to evaluate a novel LA pour-on acaricide formulation to control lone star ticks infesting cattle was completed. Objective 4. Determine genetic differences between H. longicornis populations from the U.S., and its native and invaded range through comparative molecular studies. A method was developed to maximize the recovery of quality genomic DNA from a single tick. This achievement expanded the ability to apply next generation sequencing for molecular studies on the invasive fever ticks and the Asian longhorned tick. Characterize genes known to be associated with resistance to commonly used acaricides in invasive and exotic tick species. Research continued in support of efforts by the Cattle Fever Tick Eradication Program to understand the epidemiology of acaricide resistance in fever ticks causing outbreaks in south Texas. A breakthrough involved the development of a rapid assay to ascertain the genetic variation in mutations associated with resistance to pyrethroids between fever tick populations by adapting high-resolution DNA melting analysis using samples provided by the program. Accomplishments 01 Innovative technology for integrated fever tick management. Cattle fever ticks (CFT) are foreign high-consequence pests that threaten U.S. animal agriculture because they feed on the blood of livestock they infest and transmit the microbes that cause bovine babesiosis, a disease that causes rapid death in cattle. Of the two CFT species that remain established in Mexico, the southern CFT, Rhipicephalus microplus, is more invasive than the CFT, R. annulatus. Novel approaches to manage CFT are desperately needed because they are now resistant to almost all the classes of chemicals, or acaricides, commercialized to treat infested cattle. Collaboration between ARS scientists in Kerrville, Texas, and Ft. Pierce, Florida, resulted in the creation of new technology to manage CFT. This innovative approach uses constructs for RNA interference of crucial biological processes for tick survival. 104 1 A 2019 02 Man-made barriers for integrated cattle fever tick eradication. The increased number of fever tick outbreaks in the South Texas coastal plain wildlife corridor is alarming. This problem is compounded by a knowledge gap on the ecology of the southern cattle fever tick, R. microplus, causing these outbreaks. Data analyzed by ARS scientists in Kerrville, Texas, showed that the natural landscape and other features resulting from human activity influence fever tick infestation levels in nilgai. This hoofed animal related to cattle was introduced to this ecosystem almost a century ago and is known to disperse fever ticks across the environment. Man-made barriers could be used as part of integrated fever eradication efforts in the lower part of the South Texas coastal plain wildlife corridor. 03 New and quick method to spot fever ticks resistant to pyrethroids. Pyrethroids are a class of pesticides also used to control tick infestations in livestock. However, cattle fever ticks have become resistant to the effects of pyrethroids. Quick and accurate diagnosis of pyrethroid resistance in fever tick populations infesting cattle and horses is crucial for efficient operations of the Cattle Fever Tick Eradication Program. ARS scientists in Kerrville and Edinburg, Texas, and Pullman, Washington, worked with collaborators at Northern Arizona University, and the University of Queretaro in Mexico to develop a new and quick method to spot fever ticks resistant to pyrethroids. This DNA- based assay can detect multiple changes in the gene coding for the product targeted by the action of pyrethroids. These changes, or mutations, are known to confer some level of resistance, this particular case to the pyrethroid known as permethrin. This research documented that fever ticks with any two of the three mutations showed high levels of resistance to permethrin. This molecular assay can be completed overnight.
Impacts
(N/A)
Publications
- Ojeda-Chi, M., Perez De Leon, A.A., Esteve-Gassent, M., Modarelli, J., Villegas-Perez, S. 2019. Ehrlichia canis in dogs of Mexico: Prevalence, incidence, co-infection and factors associated. Comparative Immunology Microbiology and Infectious Diseases. 67:101351.
- Goolsby, J., Moran, P.J. 2019. Field impacts of the arundo scale, Rhizaspidiotus donacis (Homoptera: Diaspididae) on Arundo donax on the Rio Grande. Subtropical Agriculture and Environments. 70:11-16.
- Showler, A., Osbrink, W.L. 2018. The arundo wasp, Tetramesa romana, does not control giant river reed, Arundo donax, in Texas, USA. Entomologia Experimentalis et Applicata. 166(11-12):883-893.
- Pereiria De Oliveira, R., Hutet, E., Paboeuf, F., Duhayon, M., Boinas, F., Perez De Leon, A.A., Filatov, S., Vial, L., Le Potier, M. 2019. Comparative vector competence of the Afrotropical soft tick Ornithodoros moubata and Palearctic species, O. erraticus and O. verrucosus, for African Swine Fever virus strains circulating in Eurasia. PLoS One. 14(11) :e0225657.
- Showler, A., Harlien, J.L., Perez De Leon, A.A. 2019. Effects of laboratory grade limonene and a commercial limonene-based insecticide on Haematobia irritans irritans (L.) (Muscidae: Diptera): deterrence, mortality, and reproduction. Journal of Medical Entomology. 56(4):1064- 1070.
- Benavidez, K.M., Guerra, T., Torres, M., Rodriguez, D., Veech, J., Hahn, D. , Miller, R., Soltero, F., Perez Ramirez, A., Perez De Leon, A.A., Castro- Arellano, I. 2019. The prevalence of Leptospira among invasive small mammals on Puerto Rican cattle farms. PLOS Neglected Tropical Diseases. 13(5):e0007236.
- Beard, B.C., Occi, J., Bonilla, D.L., Egizi, A.M., Perez De Leon, A.A., Fonseca, D.M., Mertins, J.W., Backenson, B., Bajwa, W., Barbarin, A.M., Bertone, M., Brown, J., Connally, N.P., Connell, N., Falco, R., Foust, E., James, A.M., Krell, R., Lahmers, K., Lewis, N., Little, S.E., Maillard, J., Moore, Z., Neault, M., Randall, A.R., Ruder, M.G., Saleh, M.N., Schappach, B., Schreoder, B.A., Seraphin, L., Wehtje, M., Williams, C., Wormser, G.P. , Yabsley, M.J., Halperin, W. 2018. Multistate infestation of an exotic disease vector tick Haemaphysalis longicornis. Morbidity and Mortality Weekly Reports. 67:1310-1313.
- Davis, H.N., Goolsby, J., Thomas, D.B., Badillo, I., Kariyat, R., Vitek, C. , Sekula, D. 2020. Review of major crop and animal arthropod pests of South Texas. Subtropical Agriculture and Environments. 71:36-48.
- Showler, A. 2019. Desert locust control: The effectiveness of proactive interventions and the goal of outbreak prevention. American Entomologist. 65(3):180-191.
- Showler, A., Donahue, W.A., Harlien, J.L., Donahue, M., Vinson, B. 2019. Efficacy of novaluron + pyriproxyfen (Tekko Pro) insect growth regulators against Amblyomma americanum (Acari: Ixodidae), Rhipicephalus (Boophilus) annulatus, Rhipicephalus (Boophilus) microplus, and Rhipicephalus sanguineus. Journal of Medical Entomology. 56(5):1338-1345.
- Soti, P., Goolsby, J., Racelis, A. 2020. Agricultural and environmental weeds of south Texas and their management. Subtropical Agriculture and Environments. 71:1-11.
- Sutton, G., Canavan, K., Day, M., Den, B., Goolsby, J., Cristofaro, M., McConnachie, A., Patterson, I. 2019. Grasses as suitable targets for classical weed biological control. Biocontrol. 64:605-622.
- Kim, H.J., Krishnavajhala, A., Armstrong, B.A., Perez De Leon, A.A., Filatov, S., Teele, P.D., Lopez, J.E. 2019. Humoral immune response of pigs, Sus scrofa domesticus upon repeated exposure to blood-feeding by Ornithodoros turicata Duges (Ixodida: Argasidae). Parasites & Vectors. 13:66.
- Temeyer, K.B., Schlechte, K.G., McDonough, W.P. 2019. Baculoviral expression of presumptive OP-resistance mutations in BmAChE1 of Rhipicephalus (Boophilus) microplus (Ixodida:Ixodidae) and biochemical resistance to OP inhibition. Journal of Medical Entomology. 56(5):1318- 1323.
- Goolsby, J., Hathcock, C., Vacek, A., Kariyat, R., Moran, P.J., Martinez- Jiminez, M. 2020. No evidence of non-target use of native or economic grasses and broadleaf plants by Arundo donax biological control agents. Biocontrol Science and Technology. 30(8):795-805.
- Domingues, L.N., Guerrero, F., Foil, L.D. 2019. Impacts of long-term insecticide treatment regimes on skdr and kdr pyrethroid resistance alleles in horn fly field populations. Parasitology Research. 118:2485�2497.
- Currie, C., Hewitt, D., Ortega-S, A., Schuster, G., Campbell, T., Lohmeyer, K.H., Perez De Leon, A.A. 2020. Efficacy of white tailed deer (Odocoileus virginianus) treatment for cattle fever ticks in southern Texas, USA. Journal of Wildlife Diseases. 56(3):588-596.
- Thomas, D.B., Klafke, G., Busch, J.D., Olafson, P.U., Miller, R., Mosqueda, J., Stone, N., Scoles, G.A., Wagner, D., Perez De Leon, A.A. 2020. Tracking the increase of acaricide resistance in an invasive population of cattle fever ticks, Rhipicephalus microplus (Acari: Ixodidae), and implementation of real-time PCR assays to rapidly genotype resistance mutations. Annals of the Entomological Society of America. 113(4):298-309.
- Showler, A., Perez De Leon, A.A. 2020. Landscape ecology of Rhipicephalus (Boophilus) microplus (Ixodida: Ixodidae) outbreaks in the South Texas Coastal Plain wildlife corridor including man-made barriers. Environmental Entomology. 49(3):546-552.
- Ojeda, M., Rodriguez-Vivas, R., Esteve-Gassent, M., Perez De Leon, A.A., Modarelli, J., Sandra, V. 2019. Molecular detection of rickettsial tick- borne agents in white-tailed deer (Odocoileus virginianus yucatanensis), mazama deer (Mazama temama), and the ticks they host in Yucatan, Mexico. Ticks and Tick Borne Diseases. 10(2):365-370.
- Cardoso, A., Guimaraes Dos Santos, E.G., Da Silva Lima, A., Temeyer, K.B., Perez De Leon, A.A., Costa-Junior, L.M., Dos Santos Soares, A.M. 2020. Terpenes on Rhipicephalus (Boophilus) microplus: Acaricidal activity and acetylcholinesterase inhibition. Veterinary Parasitology.
- Aguilar-Dominguez, M., Romero-Salas, D., Sanchez-Montes, S., Barradas-Pina, F.T., Rosas-Saito, G., Cruz-Romero, A., Ibarra-Priego, N., Becker, I., Lohmeyer, K.H., Perez De Leon, A.A. 2018. Occurrence of Amblyomma mixtum on the water buffalo (Bubalus bubalis) in Mexico. International Journal for Parasitology: Parasites and Wildlife. 7(3):405-408.
- Klafke, G.M., Moreno, H.C., Tidwell, J.P., Miller, R., Thomas, D.B., Feria- Arroyo, T.P., Perez De Leon, A.A. 2020. Partial characterization of the voltage-gated sodium channel gene and molecular detection of permethrin resistance in Rhipicephalus annulatus (Say, 1821). Ticks and Tick Borne Diseases.
- Showler, A., Bailee, D.N., Caesar, R.M. 2020. Effects of formic acid on Amblyomma americanum (Ixodida: Ixodidae). Journal of Medical Entomology.
- Showler, A., Dorsey, B.N., Caesar, R.M. 2020. Lethal effects of a silica gel + thyme oil (EcoVia) dusts and aqueous suspensions on Amblyomma americanum (Ixodida: Ixodidae) larvae and nymphs. Journal of Medical Entomology.
- Rodriguez-Vivas, R.I., Perez De Leon, A.A., Ojeda-Chi, M.M. 2020. The longhorned tick (Haemaphysalis longicornis): invasive exotic species that threatens animal and public health in Mexico. Bioagrociencias. 12:9-18.
- Perez De Leon, A.A., Mitchell III, R.D., Watson, D.W. 2020. Ectoparasites of cattle. Veterinary Clinics of North America. 36(1):173-185.
- Showler, A., Flores, N., Caesar, R.M., Mitchell, R.D., Perez De Leon, A.A. 2020. Lethal effects of a commercial diatomaceous earth dust product on Amblyomma americanum (Ixodida: Ixodidae) larvae and nymphs. Journal of Medical Entomology.
- Armstrong, B.A., Kneubehl, A.R., Mitchell III, R.D., Krishnavajhala, A., Teel, P.D., Perez De Leon, A.A., Lopez, J.E. 2020. Differential expression of putative Ornithodoros turicata defensins mediated by tick feeding. Frontiers in Cellular and Infection Microbiology.
- Souza Higa, L., Barradas Pina, F., Rodrigues, V., Valerio Garcia, M., Romero Salas, D., Miller, R., Perez De Leon, A.A., Cavalcante Barros, J., Andreotti, R. 2020. Evidence of acaricide resistance in different life stages of Amblyomma mixtum and Rhipicephalus microplus (Acari: Ixodidae) collected from the same farm in the state of Veracruz, Mexico. Preventive Veterinary Medicine.
- Merino, J., De La Cruz, N., Galvan, G., Perez De Leon, A.A., Burnes, J. 2020. First molecular and serological detection of Epizootic Hemorrhagic Disease virus in white tailed deer (Odocoileus virginianus) from Tamaulipas, Mexico. Brazalian Archive of Medicine Veterinaria and Zootecnia. 71(1):77-85.
- Showler, A., Osbrink, W.L., Dorsey, B.N., Caesar, R.M. 2019. Metastriate ixodid life stages protected from predatory ants in Texas. Environmental Entomology. 48(5):1063-1070.
- Ojeda-Chi, M., Rodriguez-Vivas, R., Esteve-Gassent, M., Perez De Leon, A.A. , Modarelli, J., Villegas-Perez, S. 2019. Ehrlichia canis in dogs of Mexico: Prevalence, incidence, co-infection and factors associated. Comparative Immunology Microbiology and Infectious Diseases. 67:101351.
- Merino, J.O., De La Cruz, N.I., Martinez, J., Perez De Leon, A.A., Romero- Salas, D., Esteve-Gassent, M., Lagunes-Quintanilla, R. 2020. Molecular detection of Rickettsia species in ticks collected in the Mexico-USA transboundary region. Experimental and Applied Acarology. 80:559-567.
- Vasquez, A., Goolsby, J., Vacek, A.T., Racelis, A.E., Kariyat, R.R. 2019. Incidence of the brown dog tick, Rhipicephalus sanguineus and its parasitoid, Ixodiphagus hookeri on dogs in South Texas. Subtropical Agriculture and Environments. 70:6-10.
- Bendele, K.G., Guerrero, F., Cameron, C., Bodine, D.L., Miller, R. 2019. Gene expression during the early stages of host perception and attachment in adult female Rhipicephalus microplus ticks. Experimental and Applied Acarology. 79(1):107-124.
- Showler, A., Harlien, J.L. 2019. Effects of silica based CimeXa and Drione dusts against lone star tick, Amblyomma americanum (L.)(Ixodida: Ixodidae), on cattle. Journal of Medical Entomology. 57(2):485-492.
- Hern�ndez-Velasco, A., S�nchez-Montes, S., Romero-Salas, D., Cruz-Romero, A., Jim�nez-Hern�ndez, J., Becker, I., Aguilar-Dom�nguez, M., Perez De Leon, A.A. 2020. First record of natural infection with Anaplasma marginale in sucking lice infesting the water buffalo (Bubalus bubalis) in Mexico. Parasitology Research.
- Khan, A., Mitchell, R.D., Ali Shah, S., Nasreen, N., Niaz, S., Ayaz, S., Naeem, H., Khan, L., Perez De Leon, A.A. 2019. Tick burden and tick species prevalence in small ruminants of different agencies of the Federally Administered Tribal Areas (FATA), Pakistan. International Journal of Acarology. 45(6-7):374-380.
- Khan, A., Nasreen, N.A., Niaz, S., Ayaz, S., Naeem, H., Muhammad, I., Said, F., Mitchell, R.D., Perez De Leon, A.A., Snehil, G., Kumar, S. 2019. Acaricidal efficacy of Calotropis procera (Asclepiadaceae) and Taraxacum officinale (Asteraceae) against Rhipicephalus microplus from Mardan, Pakistan. Experimental and Applied Acarology. 78(4):595-608.
- Goolsby, J., McKinney, B., Larson, D., Bennett, J. 2019. Establishment of Arundo wasp, Tetramesa romana, at Big Bend National Park. Southwestern Entomologist. 44(1):321-322.
- Guerrero, F., Bendele, K.G., Ghaffari, N., Guhlin, J., Gedye, K.R., Lawrence, K.E., Dearden, P.K., Harrop, T.W., Heath, A.C., Lun, Y., Metz, R. P., Teel, P., Perez De Leon, A.A., Biggs, P.J., Pomroy, W.E., Johnson, C.P. , Blood, P.D., Bellgard, S.E., Tompkins, D.M. 2019. The Pacific Biosciences de novo assembled genome from a parthenogenetic New Zealand wild population of the longhorned tick, Haemaphysalis longicornis Neumann, 1901. Data in Brief. 27:104602.
- Campos, K.L., Alves De Araujo, T., Showler, A., Luz, C.E., Da Silva, W.B., De Figueiredo, C., Torres, J.B., Bastos, C.S. 2019. Integration of cotton plant resistance with selected organic boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae) control tactics. Journal of Agricultural Science. 11(5).
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