Source: NORTHERN ARIZONA UNIVERSITY submitted to
PREVENTING THE SPREAD OF CATTLE FEVER IN TEXAS: USING POPULATION GENETIC TOOLS TO INCREASE THE EFFECTIVENESS OF DISEASE MANAGEMENT EFFORTS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
1005741
Grant No.
2015-67015-23047
Project No.
ARZW-2014-06322
Proposal No.
2014-06322
Multistate No.
(N/A)
Program Code
A1221
Project Start Date
Feb 15, 2015
Project End Date
Feb 14, 2018
Grant Year
2015
Project Director
Busch, J. D.
Recipient Organization
NORTHERN ARIZONA UNIVERSITY
(N/A)
FLAGSTAFF,AZ 86011
Performing Department
Microbial Genetics & Genomics
Non Technical Summary
A disease of cattle, known as cattle fever, is especially lethal to adult cattle that have not been previously exposed to this disease. This disease, which is caused by several different species of parasites and is spread by ticks, was once widespread throughout the southern US, causing annual losses to the cattle industry that would amount to more than $3 billion dollars in today's dollars. Fortunately, intensive efforts by federal and state agencies lead to the eradication of cattle fever in almost all of the US by 1960. The successful eradication of the disease was accomplished by eradicating the ticks that spread it, which are known as cattle fever ticks. Unfortunately, cattle fever ticks and cattle fever remain rampant in Mexico - a country that exports ~1 million cattle to the US every year. The reintroduction of cattle fever to the US from Mexico is only prevented by the extensive screening of cattle entering the US from Mexico, and the rigorous enforcement by the USDA of a permanent quarantine buffer zone comprising a ≈ 800 km long, eight-county portion of the Texas-Mexico border region. Despite these significant efforts by the USDA, cattle fever tick infestations have increased in permanent quarantine zone and have started to spread out of the buffer zone to the north and east. Further spread of cattle fever ticks in Texas could lead to the reintroduction of cattle fever to the southern US, which would be devastating to the US cattle industry as there is not currently a vaccine approved for use in the US.We completed an initial study that answered important questions about the populations of cattle fever ticks in southern Texas. However, to truly understand the source of tick infestations in this region it is crucial that we also understand the population structure of these species in Mexican states that export cattle to the US. There is also a need to obtain additional information about the spread of problematic cattle fever tick populations that are resistant to chemicals used to control cattle fever ticks. We propose to use DNA fingerprinting approaches to identify tick populations in Mexico that are the source of new US infestations, and evaluate whether certain tick populations are a greater threat to the US livestock industry due to their resistance to chemicals. This critical information will help the USDA improve their management strategy for this high impact disease by identifying priority tick populations for monitoring and control efforts, before tick outbreaks expand too far to manage effectively.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
31131201080100%
Knowledge Area
311 - Animal Diseases;

Subject Of Investigation
3120 - Spiders, mites, ticks, and other arthropods;

Field Of Science
1080 - Genetics;
Goals / Objectives
The overall, long-term goal of this project is to secure the productivity of the U.S. cattle industry through a better understanding of the conditions that could lead to the establishment and spread of cattle fever ticks and bovine babesiosis in Texas. Because these pathogens require tick vectors, achieving this goal depends, to a large extent, on tick control. We will use population genetic tools to help guide eradication efforts with the following two goals:• Expand our knowledge about the critical ecological and genetic mechanisms responsible for cattle fever tick infestations in Texas; and• Provide the resulting information to APHIS personnel to improve their existing efforts to control and eradicate cattle fever ticks.
Project Methods
We will use population genetic tools to help guide cattle fever tick eradication efforts in Texas. Population genetic approaches provide a powerful means to determine the origin of tick infestations in Texas. These approaches also enable us to track the spread of ticks after an initial infestation, which reveals the ecological pathways (e.g., transport via cattle or other hosts) underlying tick movements in Texas. We will investigate tick invasion and the relevance of distinct tick genetic groups with the following specific questions:1. Do the recent infestations of cattle fever ticks in Texas originate from persistently-infested premises in Texas or from source populations in Mexico?2. Which genetic groups of cattle fever ticks are ecologically established in Texas and does acaricide resistance play a role in their persistence over time?3. Are there differences in vector competence for bovine babesiosis among the major tick genetic groups?The first two questions will provide fundamental information on the origin and movement of cattle fever ticks in southern Texas, which directly informs the eradication program about the risk of Babesia reintroduction. We will use existing tick collections from the US quarantine zone to address questions 1 & 2 and supplement them with new tick collections from Mexico. The combined data from the US and Mexico will reveal how ticks are moved into Texas and, for the first time, we will define the genetic background of cattle fever ticks in Mexico. This deeper understanding of tick source populations will be highly valuable for tick control efforts. Question 3 will evaluate whether certain tick populations are a greater threat to the US livestock industry due to their efficiency as vectors of Babesia. We will utilize field-caught ticks to experimentally test rates of B. bovis acquisition and transmission by cattle fever ticks. Our collective results will allow the USDA to deploy limited resources for tick and disease control in the most effective manner by providing priority targets for surveillance and control before cattle fever ticks, and the Babesia parasites they vector, can spread farther into the US.

Progress 02/15/15 to 02/14/18

Outputs
Target Audience:Our target audiences were stakeholders in the cattle fever tick eradication program (CFTEP), including landowners, USDA-APHIS inspectors (including tick riders), the TX Animal Health Commission (TAHC), and the wider community of researchers that study Rhipicephalus ticks and Babesia parasites. In November 2016, most of our key personnel (Drs. Olafson, Scoles, Mosqueda and Nate Stone) attended the Bi-National 2016 APHIS-SAGARPA Tick Summit Meeting on November 29-30, 2016 in Weslaco, TX. This international meeting is an important venue for delivering science-based knowledge to tick management personnel and scientists in the U.S. and Mexico. Part of the meeting was a field trip to the tick quarantine zone to visit a US Port-of-Entry cattle yard and dipping vat and observe cattle importation first-hand. We discussed our genetic research with tick inspectors, many of whom are Hispanic. Our team members also traveled to Mexico to present our genetic findings at two meetings, one in Queretaro (2015) and another in Puebla (2017). Both meetings provided excellent opportunities to network with our international target audience and led to insightful discussions with tick management personnel from Mexico. We have been very proactive in disseminating our results through email and phone discussions with personnel from APHIS and TAHC. Our project accomplishments have led to a change in knowledge for APHIS personnel by providing a greater understanding of tick movements in southern TX and gaps in eradication. This knowledge will help APHIS to refine strategies for eradicating ticks on chronically infested premises and increasing their surveillance of transported cattle. When possible, we have included outreach efforts to ethnic minorities and economically disadvantaged populations, including Texas ranches owned by Hispanic landowners and small farming operations in Mexico. This project has provided excellent opportunities for scientific training to the students and technical staff in Juan Mosqueda's lab group at UAQ, who participated in field collections and laboratory research. Hands-on experiential learning has been significant for five undergraduate students at NAU, including Lindsay Sidak-Loftis, Mariel Pomeroy, Rebekah Turner, Shelby Hutton, and Bryce Schmidt. All of these students were hired by our laboratory to generate data for this project. They each worked on the tick project for 1-2 years and this experience will be a major benefit when they finish college and move on to careers in science. Changes/Problems:A significant challenge was that we were unable to collect cattle fever ticks from important locations on the Mexico border in the states of Tamaulipas and Nuevo Leon. Unsafe conditions near the US border were increasingly a problem during the time of our research project. Fortunately, Dr. Juan Mosqueda had a high success rate in all other areas of Mexico, and his team collected 63 tick samples that provided broad coverage across the entire country. Additional major problems were encountered in Goal #3 that prevented us from making a vector competence comparison. We successfully collected four populations of live ticks, three from Mexico and one from a US outbreak population. In our experimental design we needed offspring from field-collected females to compare vector competence in a calf experimentally infected with Babesia bovis; however two factors confounded this plan: 1) we received ticks at 3 different times and therefore the larvae from each population were different ages; all 4 colonies had to be synchronized before they could be placed on an infected calf, and 2) several of the populations were already infected with Babesia bigemina and had to be "cleaned" before we could test vector competence using Babesia bovis. Consequently, we were not able to proceed with the vector competence study as planned. However, in lieu of the vector competence study we were able use these colonies to answer other questions about the biology, fitness and reproductive success of each tick population. What opportunities for training and professional development has the project provided?Our team was involved with several opportunities for professional development. The first was the Bi-National 2016 APHIS-SAGARPA Tick Summit Meeting on November 29-30, 2016 in Weslaco, TX. At this meeting, our research team interacted with management personnel from both Mexico and Texas and learned about recent problems for tick eradication. In turn, we presented our latest genetic findings in scientific talks and a poster presentation. This meeting provided valuable training for our genetics technician Nate Stone, who has conducted all of the genotyping for this study but had not yet visited the TX eradication quarantine area. Over the course of this USDA project, we provided professional training for five undergraduate students at NAU who genotyped >3,000 ticks. Our students learned valuable skills in generating data, organizing our tick database, and working safely in the laboratory. Lindsay Sidak-Loftis helped design DNA assays for synthetic pyrethroid resistance and earned 4 awards during this project, including academic scholarships and research-based awards, including a Hooper Undergraduate Research Award (HURA) from NAU. She is a co-author on one of our publications on cattle fever ticks, and will pursue a graduate degree in infectious disease research starting in 2018. Mariel Pomeroy genotyped many ticks from MX, and earned a HURA scholarship during this project. Rebekah Turner is currently in her senior year, and has generated 4 datasets with our new genetic tools. During this project, Ms. Turner earned 5 awards, including 2 presentation awards and a HURA scholarship to investigate genetic variation at anti-tick vaccine loci. Shelby Hutton is currently a senior and has finalized genotypes for >3,000 ticks at 12 DNA fingerprinting markers. Ms. Hutton has earned 4 awards, including a HURA and a national-level Goldwater Fellowship. The fifth student on this project is Bryce Schmidt, who is in his junior year. Bryce has generated qPCR data on assays for tick resistance mutations. In addition, the students and technical staff in Juan Mosqueda's lab group gained excellent field and laboratory experience with this project. How have the results been disseminated to communities of interest?Over the course of this three-year project, our team members have presented at multiple scientific meetings, including: - The Symposium on Ticks and Tick-borne Diseases, Queretaro, Mexico, November 11-12, 2015. - The Bi-National 2016 APHIS-SAGARPA Tick Summit Meeting on November 29-30, 2016. - The Asociacion Mexicana de Parasitologos Veterinarios (AMPAVE) parasitology meeting in Puebla, MX, on August 9-11, 2017. - The USDA Puerto Rico Summit, San Juan, Puerto Rico, June 27, 2017 In all of these scientific meetings our key personnel were invited speakers. These were important venues for updating tick management personnel and scientists involved with the cattle fever tick and babesiosis problem in the U.S. and Mexico. During the USDA Puerto Rico Summit, Nathan Stone traveled to Puerto Rico to present our new genetic tools and highlight the great potential they have for monitoring tick populations from that island. He presented genetic data on ~100 ticks sent by our collaborator from the USDA-APHIS. The USDA audience was very enthusiastic about our genetic approach. We have also disseminated our results at scientific meetings and phone discussions with personnel from APHIS and TAHC. Our professional networking has led to insightful discussions with tick management personnel from Texas, Puerto Rico, and Mexico. We have been very proactive in disseminating our results through email and phone discussions with personnel from APHIS and TAHC. Our project accomplishments have led to a change in knowledge for APHIS personnel by providing a greater understanding of tick movements in southern TX and gaps in eradication. Disseminating this knowledge directly to APHIS will help refine strategies for eradicating ticks on chronically infested premises and increasing surveillance efforts for transported cattle. What do you plan to do during the next reporting period to accomplish the goals?This is the Final Report for this project. Our team will continue to conduct research on cattle fever ticks and babesiosis in future grants.

Impacts
What was accomplished under these goals? The main accomplishment of this project has been the development of new genetic tools to improve the security of the cattle industry in the southern US. We are using genetic data to track hidden movements of highly invasive cattle fever ticks (Rhipicephalus microplus and R. annulatus) in Mexico and Texas, identify mutations for resistance to pesticides, and screen ticks for Babesia parasites. Our project has high relevance for the management and prevention of cattle fever (bovine babesiosis), a lethal disease of cattle that occurs in Mexico and other parts of the world. Our new data suggest multiple gaps in tick control still exist in the US, including: 1) The unintended movement of ticks. Tick movements occur frequently within MX, and spillover into TX is evident. There are two main avenues of dispersal: long-distance transport of cattle by humans, and shorter movements on wildlife and stray cattle. Stray livestock from MX are important for moving ticks across the Rio Grande. 2) Ticks use wildlife as alternative hosts. White-tailed deer and exotic nilgai antelope are a major problem for tick control; they are difficult to treat with chemicals and serve as a source of ticks on domestic cattle. 3) Tick movements occur beyond the quarantine area of TX. Increasingly, ticks are spreading into the "free area" to the north, and cattle in this area are not monitored for ticks before sale or transport. 4) Resistant tick populations. Resistant ticks in MX have spilled over into TX, and 85% of new TX infestations carry resistance mutations that occur throughout MX. Some tick populations in TX also show resistance mutations for amitraz, a chemical used widely in MX. Fortunately, we did not find any evidence of Babesia in ticks sampled from TX. However, we did detect B. bovis and B. bigemina in a low proportion of ticks spread throughout MX. In contrast, we detected Anaplasma marginale in 95% of MX locations and also at 3 TX properties along the Rio Grande, highlighting the risk that pathogens such as Babesia could be re-introduced to the US. This new information helps the USDA-APHIS to identify significant gaps in tick control that will prevent the establishment of bovine babesiosis. We also used our new genetic tools to study ticks in Puerto Rico. Two distinct genetic groups occur in the southwestern portion of the island, and all ticks had genotypes that were susceptible to synthetic pyrethroids. Goal #1: Determine the genetic sources of tick populations in TX. (100% complete, 2018) Our main activities were 1) collected >1,500 new tick samples from MX (63 locations) and >1,000 from TX; 2) performed genetic analysis on all tick collections; 3) managed team activities through live meetings and teleconferences. We generated 4 types of genetic data: 1) DNA fingerprinting markers (12 loci) 2) DNA sequence from 6 markers that amplify 1,400 bp of the mitochondrial genome. 3) DNA sequence from 5 markers that amplify segments of 3 genes: one gene for resistance to synthetic pyrethroid chemicals and the others are associated with amitraz resistance 4) DNA sequence from 9 markers to screen for cattle fever pathogens (Babesia bovis, B. bigemina, and A. marginale). We used our genetic tools to analyze two large R. microplus outbreaks north of the TEQA. The first started in Cameron Co. and spread north, reaching as far as Kleberg and Jim Wells Counties; the second was discovered in Live Oak Co. 110 miles north of the TEQA. Our data clearly show that these two outbreaks are not genetically related. The Cameron Co. population was resistant to pyrethroids and spread to deer and nilgai. Our findings confirmed 1) ticks can move freely between wildlife and cattle, and 2) wildlife can spread resistant ticks. This is a major problem for the eradication program, because it is virtually impossible to remove or treat ticks on wildlife, which can easily spread ticks to ranches that were originally tick-free. Goal #2: Determine the mechanism of persistence for tick populations in Texas and Mexico. (100% complete, 2018) In this goal, we analyzed tick populations that had been sampled repeatedly over time. We investigated samples from 8 TX areas (4km diameter each) that were chronically re-infested over 4-10 year timespans, and found two main mechanisms for persistence. First, a single genetic population can persist year after year, as was found in one area of Zapata county where the genetic signature was very stable across 7 years. This tick population has never been fully eradicated and probably persists on deer. The second mechanism is a cycle of eradication followed by frequent re-infestion. In this case, genetic data show a pattern of increasing genetic structure over time. This suggests that new ticks frequently arrive from different genetic sources. Acaricide resistance is not yet an important persistence mechanism in TX and we never found resistant genotypes that persisted through time. However, acaricide resistance is more likely to play a role in the long-term persistence of tick populations in MX. Goal #3: Evaluate differences in vector competence for bovine babesiosis among major tick genetic groups. (100% complete, 2018) We used 4 field collections of ticks (3 from MX, 1 from TX) to start lab colonies in Dr. Glen Scoles lab at WSU for this goal. Biological data from these ticks did not indicate any important differences in fitness-related phenotypes such as the time to oviposition, ratio of female replete weight to egg weight, or hatching success. Future testing will be required to evaluate whether subtle differences exist in the vector competence of these populations. An unexpected discovery from this work was the identification of a little-known bacterial species, Borrelia theileria, in ticks from MX. This bacterium may be a cattle pathogen; it was found in 1 of the MX collections then spread to all 4 lab colonies after rearing on a single cow. It is transmitted both vertically and horizontally across successive tick generations in the lab. Thus, it has the potential to serve as an early indicator species for identifying the risk of Babesia crossing from MX into TX. We have developed a genetic assay for this bacterium and will screen ticks in a future project. OVERALL IMPACTS This project has increased the understanding of cattle fever tick movements into US cattle. This information is valuable to eradication personnel (APHIS and TAHC) who make decisions about preventing bovine babesios through tick eradication. Our findings also have impacts for cattle producers in the US, especially small operations in southern TX where ticks are established. Because we focused on ticks sampled from MX, our findings have impacts for landowners and ranchers in that country. Our genetic data suggest that ticks are spread relatively short distances by wildlife and much longer distances when humans transport infested cattle. These findings have identified two important gaps in tick control: 1) infested stray cattle from MX that cross into TX, and 2) inadequate tick monitoring and/or treatment of cattle shipped from infested ranches in southern TX. Many properties north of the TX quarantine zone have become temporarily infested and these ticks are not detected quickly enough to prevent their transport. Another major problem is that tick resistance to chemicals is spreading from MX into TX. Our genotyping data predict that resistance to synthetic pyrethroids and amitraz occurs in tick populations across the entire country of MX, and unfortunately, many new infestations in TX are also resistant. TX ranchers and APHIS tick eradication personnel need to choose appropriate pesticides to eradicate ticks; if resistant ticks are treated with the wrong chemical, a resistant population will persist and spread to wildlife hosts. In most cases, synthetic pyrethroids should not be used in TX, because almost all current tick infestations are resistant to this class of chemicals.

Publications

  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Araya-Anchetta A, Busch JD, Scoles GA, Wagner DM. Thirty years of tick population genetics: A comprehensive review. Infection, Genetics and Evolution. 2015: 29:164-79
  • Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: J. D. Busch, N. E. Stone, P. U. Olafson, R. B. Davey, G. Buckmeier, D. Bodine, L. Sidak-Loftis, J. R. Giles, A. T. Peterson, J. M. Pounds, D. M. Kammalah, K. H. Lohmeyer, R. Duhaime, R. J. Miller, J. Mosqueda, G. A. Scoles, and D. M. Wagner. 2015. Population genetic tools for cattle fever tick eradication in southern Texas. Symposium on Ticks and Tick-borne Diseases, Queretaro, Mexico, November 2015. (Talk)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: D. M. Wagner, N. E. Stone, P. U. Olafson, R. B. Davey, G. Buckmeier, D. Bodine, L. Sidak-Loftis, J. R. Giles, A. T. Peterson, J. M. Pounds, D. M. Kammalah, K. H. Lohmeyer, R. Duhaime, R. J. Miller, J. Mosqueda, G. A. Scoles, and J. D. Busch. 2015. Resistance profiles and invasive potential of cattle fever ticks in the United States. Symposium on Ticks and Tick-borne Diseases, Queretaro, Mexico, November 2015. (Talk)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: N. E. Stone, R. E. Turner, P. U. Olafson, G. Buckmeier, R. Duhaime, D. Thomas, G. A. Scoles, J. Mosqueda, D. M. Wagner, and J. D. Busch. 2016. 85% of cattle fever ticks from Texas (2014-2016) and 96% from Mexico (2016) carry pyrethroid resistant genotypes. U.S./Mexico Cattle Fever Tick Summit, Weslaco, TX, November 2016. (Poster)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: J. D. Busch, J. Mosqueda, N. E. Stone, R. E. Turner, M. Pomeroy, S. M. Hutton, D. Thomas, G. Buckmeier, P. U. Olafson, G. A. Scoles, and D. M. Wagner. 2016. Preventing the spread of cattle fever in Texas: using population genetic tools to increase the effectiveness of disease management efforts. USDA-NIFA 2016 Animal Health and Animal Well-Being Project Director Workshop, Chicago Downtown Marriott, Chicago, IL, December 2, 2016. (Talk)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Rebekah E. Turner, Nathan E. Stone, H. Joel Hutcheson, Pia U. Olafson, Greta Buckmeier, Donald B. Thomas, Glen A. Scoles, Juan Mosqueda, David M. Wagner, and Joseph D. Busch. 2017. Screening Ticks Intercepted on Mexican Cattle at the Texas Border for Cattle Fever Pathogens (Anaplasma marginale and Babesia spp.) and DNA Mutations Associated with Pesticide Resistance. NAU 10th Annual Undergraduate Symposium, Flagstaff, Arizona, April 2017 (Poster) and American Society of Microbiologists, Arizona and Southern Nevada Branch, Tucson, AZ, April 2017. (Talk: selected as runner-up undergraduate presentation)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Shelby M. Hutton, Nathan E. Stone, Rebekah E. Turner, Juan Mosqueda, Mariel Pomeroy, Donald B. Thomas, Greta Buckmeier, Pia U. Olafson, Glen A. Scoles, David M. Wagner, and Joseph D. Busch. 2017. Using molecular tools to identify genetic sources of ticks that vector cattle fever parasites in Texas and Mexico. NAU 10th Annual Undergraduate Symposium, Flagstaff, Arizona, April 2017 and American Society of Microbiologists, Arizona and Southern Nevada Branch, Tucson, AZ, April 2017. (Poster)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Nathan E. Stone, Pia Olafson, Shelby Hutton, Rebekah E. Turner, Bryce Schmidt, Don Thomas, Ronald B. Davey, Greta Buckmeier, Roberta Duhaime, Robert J. Miller, Juan Mosqueda, Glen Scoles, David M. Wagner, Joseph D. Busch. 2017. Genetic Tools Illuminate Cattle Fever Tick Movement, Acaricide Resistance Status, and Pathogen Distribution in North America. USDA Puerto Rico Summit, San Juan, Puerto Rico, June 2017. (Invited Talk)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Joseph D. Busch, Nathan E. Stone, Rebekah E. Turner, Shelby M. Hutton, Bryce A. Schmidt, Pia Olafson, Greta Buckmeier, Donald Thomas, Glen Scoles, Juan Mosqueda, and David M. Wagner. Genetic tools for identifying acaricide resistant populations of Rhipicephalus microplus. 10th Congress for the ASOCIACI�N MEXICANA DE PARASIT�LOGOS VETERINARIOS (AMPAVE) in Puebla, Mexico, August 9-11, 2017. (Invited Talk)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Rebekah E. Turner, Ana Araya-Anchetta, Nathan E. Stone, Jillian Lewis, Donald B. Thomas, Greta Buckmeier, Pia U. Olafson, David M. Wagner, and Joseph D. Busch. 2018. Genetic data reveal cryptic movements of cattle fever ticks on wildlife and stray livestock from Mexico into Texas. American Society of Microbiologists, Arizona and Southern Nevada Branch, Las Vegas, NV, April 2018. (Talk earned Undergraduate presentation award)
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Bryce Anthony Schmidt, Shelby M. Hutton, Nathan E. Stone, Rebekah E. Turner, Juan Mosqueda, Lindsay C. Sidak-Loftis, Mariel Pomeroy, Donald B. Thomas, Greta Buckmeier, Pia U. Olafson, Glen A. Scoles, David M. Wagner, and Joseph D. Busch. 2017. Identifying genetic sources and cryptic movements of recent (2014-2016) Rhipicephalus microplus tick infestations in southern Texas. NAU 10th Annual Undergraduate Symposium, Flagstaff, Arizona, April 2018 (Poster)


Progress 02/15/16 to 02/14/17

Outputs
Target Audience:Our target audiences are U.S. stakeholders in the cattle fever tick eradication program (CFTEP) including beef and dairy producers, ranchers, private landowners, wildlife hunters/game ranches in the border region of Texas and Mexico, USDA-APHIS-VS CFTEP personnel (including mounted patrol inspectors), the Texas Animal Health Commission (TAHC), and the wider community of researchers and students that study Rhipicephalus ticks and Babesia parasites. Because part of our project takes place in Mexico through our collaboration with Dr. Juan Mosqueda at the Universidad Autónoma de Querétaro (UAQ), additional target audiences are Mexican cattle producers, ranchers, landowners, scientists, and students, as well as personnel involved in the national tick control program (Campaña Nacional para el Control de la Garrapata Boophilus spp.). Most of our key personnel (Drs. Mosqueda, Scoles, Olafson, and Nate Stone) and USDA collaborators (Drs. Don Thomas, Roberta Duhaime, and Massaro Ueti) attended the Bi-National 2016 APHIS-SAGARPA Tick Summit Meeting on November 29-30, 2016, held in Weslaco, TX. Juan Mosqueda presented a talk entitled "Cattle fever tick vaccine: Guidelines for Assessment", Glen Scoles presented a talk on the "Biology and life cycle of Boophilus cattle fever ticks and associated diseases" and Nate Stone presented a poster with our latest findings entitled " Permethrin resistance in cattle fever tick ticks from Mexico and Texas". Our team interacted with researchers and tick management personnel from Mexico and the US. This networking opportunity involved many insightful discussions about the cattle fever tick problem. Our key personnel toured important locations for cattle fever tick control, including 1) the USDA-APHIS CFT research laboratory run by Dr. Don Thomas in Edinburg, TX, 2) the cattle inspection station/dipping vat at the Pharr Texas Port of Entry, and 3) a tick check station at the Laguna Atascosa National Wildlife Refuge. Since our research team was already gathered in Weslaco, we held our annual team meeting on November 29 after the Tick Summit had concluded. The team meeting was held at the USDA-APHIS CFT research laboratory, with Drs. Busch and Wagner joining via teleconference. Additional audiences for our project include students (both undergraduate and graduate) at UAQ and NAU. Dr. Mosqueda's students are involved with collecting ticks and generating data for our project. This work has provided these minority students with excellent educational opportunities and new scientific knowledge. Changes/Problems:Our most significant challenge in Year 2 was attempting to collect ticks from new locations in northern Mexico, in the states of Tamaulipas and Nuevo Leon. This has been difficult because of unsafe conditions near the US border. Despite this problem, Dr. Juan Mosqueda has been highly successful at asking collaborators for tick collections from the central and southern portions of these states. His tick samples from Mexico provide broad coverage across the entire country. What opportunities for training and professional development has the project provided?A key opportunity for professional development occurred at the Bi-National 2016 APHIS-SAGARPA Tick Summit Meeting on November 29-30, 2016 in Weslaco, TX. Our research team learned about recent developments in tick eradication from management personnel working in Mexico and Texas. We presented our latest findings in scientific talks and a poster presentation. This meeting provided valuable training for our genetics technician Nate Stone, who has conducted all of the genotyping for this study but has not had the opportunity to visit the Texas quarantine area. In addition, the students and technical staff in Juan Mosqueda's lab group are gaining excellent field and laboratory experience with this project. How have the results been disseminated to communities of interest? Our team members attended the upcoming 2016 APHIS-SAGARPA Cattle Fever Tick Summit to be held on Nov 29-30 in Weslaco, TX. Most key personnel from our project (Mosqueda, Olafson, Scoles, and Nathan Stone) attended this conference. Dr. Mosqueda, Glen Scoles, and Nathan Stone presented their latest findings from this project. This bi-national meeting is an important venue for updating management personnel and scientists involved with the cattle fever tick problem in the U.S. and Mexico. We have also been very proactive in disseminating our results through email and phone discussions with personnel from APHIS and TAHC. Our project accomplishments have led to a change in knowledge for APHIS personnel by providing a greater understanding of tick movements in southern Texas. This knowledge will help APHIS to refine strategies for eradicating ticks on chronically infested premises and increasing their surveillance of transported cattle. We have ackowledged funding from USDA-NIFA in all scientific presentations and discussions. What do you plan to do during the next reporting period to accomplish the goals? We will continue to sample ticks from new locations in Mexico and collect ticks from chronic locations in Texas. We will perform a large amount of tick genotyping in the coming months, and begin an in-depth statistical analysis. We will also hold team meetings via teleconferencing to monitor our progress and plan our goals for Year 3.

Impacts
What was accomplished under these goals? The primary outcome of this project will be to improve the security of the cattle industry in the southern US by preventing re-introduction of Babesia parasites that cause cattle fever (or babesiosis) in Mexico and other parts of the world. Because these diseases are transmitted only by cattle fever ticks (Rhipicephalus microplus and R. annulatus), the disease threat can, in theory, be removed by eradicating the tick vectors; hence, the management approach adopted by the USDA-APHIS is to control cattle fever ticks. However, the tick eradication quarantine area (TEQA) along the Rio Grande border has been compromised increasingly during the last 10 years, especially from tick populations that are resistant to chemicals used for their control (acaricides). Our genetic study will provide valuable information to APHIS by identifying tick populations in Mexico that are the source of new US infestations. We are also screening ticks to see if they carry DNA mutations for resistance to chemical acaricides. Our work will directly help personnel (APHIS and the Texas Animal Health Commission (TAHC)) who are deeply involved with managing the cattle fever tick problem in Texas working. Our research also has impacts for cattle producers in the US, especially small farming operations in southern Texas. Because an important component of this project involves sampling ticks from Mexico, this work is also targeted at landowners and ranchers in that country. Goal #1: Determine the genetic sources of tick populations in Texas. (50% complete; will be 100% complete in Y3) We made progress on the major activities for this goal by 1) collecting >2,000 new tick samples from Texas and Mexico, 2) genotyping these new tick collections, and 3) managing team activities through teleconferences. The worst R. microplus outbreak in decades started in 2014 along the Gulf Coast of Texas and has continued into 2016. New tick infestations breached the TEQA in Cameron County and spread northward, reaching as far north as Live Oak, Kleberg, and Jim Wells Counties. This means the vast majority of new infestations were located in the "tick-free" area of southern Texas. In a number of cases, ticks were unknowingly transported on cattle sold from infested herds. Our genotyping data suggest that three distinct tick populations were initially introduced into Cameron County, two of which combined and continued to spread northward along the Gulf Coast. Many of the new infestations were resistannt to synthetic pyrethroid chemicals (especially permethrin), and we tracked the spread of acaricide-resistant ticks using DNA assays specific to a gene that determines resistance or susceptibility. This genetic tool can be used to rapidly screen many ticks, and we found that resistant ticks had been transported into Willacy, Kleberg, and Jim Wells Counties. Another problem is that ticks are using alternative hosts such as white-tailed deer (WTD) and exotic nilgai antelope, and the genetic data suggest ticks are being spread among neighboring ranches on these wildlife species. This is a major problem, because it is virtually impossible to remove or treat ticks from wildlife and these alternative hosts can easily spread ticks to ranches that were originally tick-free. We have also been genotyping tick populations collected from throughout Mexico, and found that resistance to pyrethroid acaricides is found across the entire country: 96% of the locations we sampled have resistance mutations. These mutations are spreading to Texas, where 85% of new infestations since 2014 carry the same resistance mutations as found in Mexico. These genetic data also suggest that tick movements are generally common in Mexico, leading to the spread of chemical resistance and resulting in high levels of genetic diversity. Some of these movements have led to ticks infesting US cattle near the border and probably came from infested stray livestock and wildlife from Mexico that crossed the Rio Grande. Goal #2: Determine the mechanism of persistence for tick populations in Texas and Mexico. (40% complete; will be 100% complete in Y3) We made progress on the major activities for this goal by re-sampling locations in Texas and Mexico that experience chronic re-infestation over time. At two Texas locations (in Zapata and Starr Cos.) these samples span nearly a decade, while the timespan at other sites (in Cameron Co.) is 1-2 years. Although R. microplus on Texas cattle are removed within a short time of detection, we propose two main mechanisms for tick persistence. The first is that cattle fever ticks remain ecologically established in the TEQA on alternate hosts such as WTD and nilgai. Ticks from these hosts are able to re-infest cattle when the opportunity arises. The second is that acaricide resistance develops over time and leads to chronic tick infestations. Is also possible that both mechanisms could act together in a single population of ticks. For example, at one chronic ranch in Cameron County, ticks commonly occur on WTD, nilgai, and cattle, and most of these ticks are resistant to permethrin. Goal #3: (20% complete; will be 100% complete in Y3) Evaluate differences in vector competence for bovine babesiosis among major tick genetic groups. Our vector competence study is underway and we have accomplished the collection of ticks from 7 locations in Mexico. Adult females with eggs have been shipped alive to our collaborator at the USDA, Dr. Glen Scoles. We are in the process of genotyping these samples to see if they fall into distinct genetic groups. We want to compare acaricide-resistant versus susceptible ticks to see if chemical resistance impacts the ability of ticks to vector bovine babesiosis. OVERALL IMPACTS This project has led to an increase in the understanding of cattle fever tick movements that result in new infestations of chemical-resistant ticks on US cattle. Cattle fever ticks have become established on wildlife in northern Mexico and southern Texas, including white-tailed deer and exotic nilgai antelope, and these alternative hosts have become a major source of ticks on domestic cattle. Our genetic data suggest that ticks are spread relatively short distances by wildlife and much longer distances by human transport of infested cattle. A growing problem is that many properties outside of the permanent quarantine zone in southern Texas have become infested but the ticks are not detected quickly enough to provide timely eradication. Cattle in this area are free to be sold and transported without an inspection or treatment for ticks, and ticks have been moved on infested cattle far to the north of the quarantine zone. Another major problem is that resistance to synthetic pyrethroid pesticides occurs in tick populations across the entire country of Mexico, and unfortunately, many new infestations in Texas are also resistant. It is important for TX ranchers and APHIS tick eradication personnel to understand the importance of choosing appropriate pesticides to eradicate ticks before they become established on cattle and move to wildlife hosts. In most cases, synthetic pyrethroids should not be used because almost all current tick infestations in Texas are resistant to this class of chemicals, and resistant ticks are being spread by deer and nilgai. This information is valuable to ranchers and eradication personnel (APHIS and TAHC) who make decisions about eradication strategies and pesticide usage.

Publications

  • Type: Conference Papers and Presentations Status: Other Year Published: 2016 Citation: Other (Presentations): Four of our key personnel attended the Bi-National 2016 APHIS-SAGARPA Cattle Fever Tick Summit in Weslaco, TX on November 29-30, 2016. At this conference, our team participatde in outreach activities with cattle fever tick control managers from APHIS and TAHC. We provided new genetic information to the cattle fever tick problem through presentations from three members of our research team: 1. Juan Mosqueda Gualito. Cattle fever tick vaccine: Guidelines for Assessment. Nov. 29, 2016 (oral presentation) 2. Glen Scoles. Biology and life cycle of Boophilus cattle fever ticks and associated diseases. Nov. 29, 2016 (oral presentation) 3. Nathan E. Stone. Permethrin resistance in cattle fever tick ticks from Mexico and Texas. Nov. 30, 2016 (poster presentation)


Progress 02/15/15 to 02/14/16

Outputs
Target Audience:Our target audiences were U.S. stakeholders in the cattle fever tick eradication program (CFTEP), including landowners, USDA-APHIS tick personnel (including mounted patrol inspectors), the Texas Animal Health Commission, and the wider community of researchers that study Rhipicephalus ticks and Babesia parasites. Because part of our project takes place in Mexico through our collaboration with Dr. Juan Mosqueda at the Universidad Autónoma de Querétaro (UAQ), additional target audiences are Mexican landowners, ranchers, scientists, and students, as well as personnel involved in the Mexican national government tick control program (Campaña Nacional para el Control de la Garrapata Boophilus spp.). During November 9-13, 2015, all key personnel from our project (Drs. Wagner, Mosqueda, Scoles, Olafson, and Busch) met at UAQ in Querétaro, MX, for our annual research team meeting. This trip was chosen to coincide with an international meeting organized by Dr. Mosqueda entitled "Symposium on Ticks and Tick-Borne Diseases". All members of our team presented 50-minute talks at this meeting and discussed our latest findings with researchers and tick management personnel from Mexico and the US. This professional workshop led to problem-solving discussions with other tick researchers who are trying to find innovative approaches for tick eradication in both countries. As part of our research and extension efforts, we also sampled ticks from small farms in the state of Querétaro. We had a chance to meet landowners and ranchers and discussed the extensive tick problem in Mexico. These outreach opportunities provided excellent networking with racial minority target audiences who are economically and educationally disadvantaged. Several students (both undergraduate and graduate) in Dr. Mosqueda's laboratory at UAQ are involved with collecting ticks and generating data for our project. This work has provided these minority students with excellent educational opportunities and new scientific knowledge. Changes/Problems:Our most significant challenge for Year 1 was getting all the appropriate paperwork in place for the new subcontract to Dr. Juan Mosqueda at the Universidad Autónoma de Querétaro (UAQ). UAQ had never before received funding from USDA in the past and, therefore, had never set up a DUNS number or SAM registration. Setting up this paperwork at UAQ has taken most of Year 1, which is why the rate of expenditure has been behind schedule for UAQ. But these problems were all recently resolved.Dr. Mosqueda has made tick collections locally (in the state of Querétaro) and will collect ticks from many new locations in central and northern Mexico during Year 2. What opportunities for training and professional development has the project provided?A key opportunity for professional development was provided by our recent trip to Mexico where we learned from Mexican tick researchers and also shared our knowledge with them, including with many students that were in the audience at the symposium. How have the results been disseminated to communities of interest?Our team member, Dr. Juan Mosqueda, organized a scientific meeting entitled "Symposium on Ticks and Tick-Borne Diseases". This special symposium took place at UAQ in Juriquilla, Qro, Mexico (Nov. 11-13). All key personnel from our project (Wagner, Mosqueda, Olafson, Scoles, and Busch) presented 50-minute talks to other researchers working on tick eradication. This symposium also served as the basis of training for other researchers and students involved with the cattle fever tick problem in the U.S. and Mexico. We have also been very proactive in disseminating our results through email and phone discussions with personnel from APHIS and TAHC. Upon completing our genetic analyses of the tick outbreak along the Gulf Coast of Texas we communicated our results to key personnel at APHIS and TAHC. Our project accomplishments have led to a change in knowledge for APHIS personnel by providing a greater understanding of tick movements in southern Texas. This knowledge will help APHIS to refine strategies for eradicating ticks on chronically infested premises and increasing their surveillance of transported cattle. What do you plan to do during the next reporting period to accomplish the goals?We will continue to sample ticks from new locations in Mexico and collect ticks from chronic locations in Texas. We have many new DNA extractions to perform in the coming months. We will also hold team meetings via teleconferencing to monitor our progress and plan important tick collections for Year 2.

Impacts
What was accomplished under these goals? The goal of this project is to improve the security of the cattle industry in the southern US by preventing the re-introduction of Babesia parasites that cause cattle fever (or babesiosis) in Mexico and other parts of the world. Because these diseases are transmitted only by cattle fever ticks (Rhipicephalus microplus and R. annulatus), the disease threat can, in theory, be removed by eradicating the tick vectors; hence, the management approach adopted by the USDA-APHIS is to control cattle fever ticks. However, the tick eradication quarantine area (TEQA) along the Rio Grande border has been compromised increasingly during the last 10 years, especially from tick populations that are resistant to control chemicals (acaricides). Our genetic study will provide valuable information to APHIS by identifying tick populations in Mexico that are the source of new US infestations. We are also screening ticks to see if they carry DNA mutations for resistance to chemical acaricides. Our work will directly help personnel (APHIS and the Texas Animal Health Commission [TAHC]) who are deeply involved with managing the cattle fever tick problem in Texas. Our research also has impacts for cattle producers in the US, especially small farming operations in southern Texas. Because an important component of this project involves sampling ticks from Mexico, this work is also targeted at landowners and ranchers in that country. Goal #1: Determine the genetic sources of tick populations in Texas. We made progress on the major activities for this goal by 1) collecting new tick samples from Texas and Mexico, 2) genotyping these new tick collections, and 3) holding our initial team meeting in Mexico. The worst R. microplus outbreak in decades occurred along the Gulf Coast of Texas in 2014-2015. New tick infestations breached the permanent Texas Eradication Quarantine Area (or TEQA) in Cameron County and spread northward, reaching as far north as Kleberg and Jim Wells Cos. This means nearly all new infestations were located in the "tick-free" area of southern Texas. Because this outbreak was an urgent concern for the tick eradication program, the USDA quickly sent us tick DNA and our efforts in Year 1 were focused on genotyping these tick collections. Using 11 DNA fingerprinting markers, we found that three genetic groups had been introduced into Cameron County. Two of the genetic groups (one of which was resistant to the acaricide Permethrin) began to interbreed and spread northward along the Gulf Coast. We tracked the spread of acaricides-resistant ticks using three DNA assays specific to a gene that determines resistance or susceptibility. This genetic tool can be used to rapidly screen ticks, and we found that resistant ticks had been transported into Willacy and Kleberg Cos. and most likely came from a single ranch in Cameron Co. that unknowingly sold infested cattle. Resistant ticks were also found on alternative hosts such as white-tailed deer (WTD) and exotic nilgai antelope. This is a major problem, because it is virtually impossible to remove or treat ticks from these wildlife species and these alternative hosts can easily move among neighboring ranches, thereby spreading ticks to cattle that were originally tick-free. Upon completing our genetic analyses in May 2015, we communicated our results to key personnel in USDA-APHIS. In this capacity, we offered our professional services as consultants for the cattle fever tick eradication program and participated in multiple phone conferences. Our rapid genetic analysis helped APHIS by providing key information that could not be known otherwise. For instance, we provided traceback information on ticks that were suspected to have originated from a single source ranch in Cameron Co. With genetic data, we were able to validate that this ranch was indeed the most likely source of ticks. There was one exception, however, in which cattle were shipped from this chronically infested property to a new location in Hidalgo County. Genetic analysis revealed that the cattle most likely acquired ticks after transport, rather than from the original suspected source ranch. Goal #2: Determine the mechanism of persistence for tick populations in Texas and Mexico. Although new infestations of R. microplus on Texas cattle are eradicated within a short time of detection, these ticks remain ecologically established in the TEQA on alternate hosts such as WTD and nilgai. Our past data strongly suggest that ticks from a single location will use any host freely, whether cattle, WTD, nilgai, or other exotic species (e.g., European red deer). We made progress on the major activities for this goal by identifying priority tick collections from Texas and Mexico that have been sampled since 2011. In our Year 1 team meeting in Querétaro, Mexico, we decided to continue sampling chronic sites in Zapata and Starr Cos. To deepen our understanding of the new tick outbreaks along the Gulf Coast, we have started to conduct genotyping analyses on a new chronic ranch in Cameron County that was the source of many cattle that were transported while infested (described above). So far, our findings indicate that this ranch has a diverse population of ticks that are shared amongst cattle, WTD, and nilgai. Many of these ticks have mutations that will make them resistant to permethrin. As a result of our genetic data, the rancher and eradication personnel from APHIS and TAHC understand the importance of not using permethrin as a chemical for tick control on this property. Goal #3: Evaluate difference in vector competence for bovine babesiosis among major tick genetic groups. This will be an important goal for Year 2 and, therefore, we have not worked on this goal in our Year 1 effort. At our first team meeting in Mexico we discussed this goal and agreed on a strategy to prioritize tick collections so that we sample from several distinct genetic groups. We especially want to compare acaricide-resistant versus susceptible ticks to see if chemical resistance impacts the ability of ticks to vector bovine babesiosis.

Publications