2008 Annual Report
1a.Objectives (from AD-416)
The overall objective of this research is to support the needs of APHIS, VS and citizens of the U.S. by developing practical and efficacious technologies, strategies, and epidemiological tools to control ticks of medical and veterinary importance feeding on cattle, white-tailed deer, and other important hosts in efforts both to maintain eradication of cattle fever ticks from the U.S. and to reduce risk of human infection with tick-borne disease agents.
1b.Approach (from AD-416)
Evaluate procedures employed by APHIS/VS to eradicate cattle fever ticks, evaluate new acaricides with unique chemistries, and develop treatment strategies for their use to control outbreaks of susceptible and resistant Boophilus ticks. Use rainfall simulation apparatus to determine if rainfall soon after cattle are dipped in coumaphos will reduce efficacy, and evaluate efficacy of higher than recommended concentrations of amitraz and coumaphos to control amitraz and coumaphos resistant ticks. Develop and evaluate technology to control ticks of medical and veterinary importance by treating white-tailed deer and exotic ungulate species. Determine if deer alone can sustain populations of Boophilus ticks under experimental quarantined field conditions, and if so, evaluate 4-Poster Deer Treatment Bait Stations and macrocyclic lactone-medicated whole kernel corn in eradicating these experimental populations. Develop geographical information system (GIS) databases and create diagnostic and predictive epidemiological models from records of historical Boophilus infestations for use by VS to aid in identifying areas at high risk of re-infestation. Use these databases to generate maps, overlays, and other data sets requested for previously infested premises to be used and evaluated by VS as practical aids in their efforts to implement eradication procedures and regulations.
Research to further develop technologies to control or eliminate ticks feeding on white-tailed deer has resulted in progress on a wide variety of efforts. In attempts to prevent feral hogs and javelina from accessing and destroying '4-Poster' Deer Treatment Bait Stations deployed to eradicate fever ticks along the Texas-Mexico border, circular fenced exclosures were designed and erected around '4-Posters' to permit deer but exclude hogs. Exclosures both with and without electric fence wires were tested, and the lower fences with the added electric fence wires were considered more effective than the higher fences. In other attempts to exclude hogs, '4-Posters' were raised to various heights on 'T-posts' driven into the ground; however, at maximum heights for deer, hogs continued to gain access or destroy them. Major efforts are underway to develop acaricide treatment adapters to retrofit ranchers' existing protein feeders for deer in efforts to treat deer for fever ticks yet obviate the need for construction or purchase of additional feeders. Considering the current crisis with fever tick infestations in South Texas, this effort has been expedited and is near completion. Extensive work has been done in developing an automated and much more precise method of quantifying hatchability of tick egg masses to support ongoing studies of efficacy of commercial acaricides for potential use in the fever tick eradication program. ARS has worked closely with a CRADA partner to develop and produce a robotically, electronically, and computer-enhanced 5th generation ARS automatic collaring and treatment device for white-tailed deer. The device has been completed, and field tests to collar and de-collar deer have begun. Rather than leaving the device unattended in the field for extended periods while deer become accustomed to it, a non-functional sham device has been designed and built for this purpose. Current regulations of the Cattle Fever Tick Eradication Program require that cattle held on tick-infested premises be rounded up and treated at 14-day intervals usually for 9 months. We are currently evaluating long-acting injectable macrocyclic lactone acaricides to determine feasibility of using them to reduce gathering and treatments to 28-day intervals. This would halve the number of required gatherings, thus significantly reducing labor costs of treatment for APHIS and gathering costs for ranchers. The GIS database of historical infestation and remediation information from APHIS continues to grow, over 90% of available data from Zapata County (the county with by far the greatest number of infested premises) has been obtained and entered, and feedback from the database including updated maps of current and historical infested and adjacent premises is greatly assisting the CFTEP in planning and implementing remediation procedures. (NP104; Component 4, Goal 4.1.1; Goal 4.1.2)
Fever ticks collected from U.S. outbreaks were evaluated for resistance to acaricides:
There is a growing concern among CFTEP personnel that outbreak populations of fever ticks in the U.S. that originated in Mexico may contain ticks resistant to acaricides being used in the U.S. to maintain eradication. Scientists at the CFTRL have used discriminating dose bioassays to evaluate the acaricide susceptibility of 45 different outbreak strains of cattle fever ticks that were submitted by CFTEP inspectors during FY 2008. All of the strains tested thus far have been determined to be susceptible to all major classes of acaricides. This informs field workers in CFTEP that established protocols regarding acaricide use should be sufficient for eradication. (NP104; Component 4; Goal 4.1.1)
A study to evaluate the efficacy of a long-lasting formulation of ivermectin:
Label claims for a long-lasting formulation of ivermectin suggested that control would last for 75 days following application of the product. Results showed that the formulation provided a much shorter residual protection against southern cattle ticks than the claim listed on the label of the material. Data showed that residual protection from re-infestation only remained >99% for 14 days, and by 28 days post-treatment the efficacy was reduced to 70%. Thus this product only has 14 days of viability relative to the standard 99% level of control that is considered to be acceptable in the eradication program. (NP104; Component 4; Goal 4.1.1)
Evaluate the effectiveness of the non-target excluder for the '4-Poster':
Through a collaborative effort with ARS in Beltsville, MD, a multi-year field test of a non-target animal excluder retrofitted to '4-Posters' deployed at the Goddard Space Flight Center, MD, was completed, and demonstrated reduced feeding and fouling of the devices by non-target animals while not interfering with use of the devices by deer. U.S. Patent 7,308,867 was granted December 18, 2007, for a device similar to the one tested in Maryland that was specifically designed as an add-on to the commercially available polyethylene '4-Poster' Deer Treatment Bait Station. (NP104; Component 4; Goal 4.1.1.)
Rainfall may reduce efficacy of dipping to eliminate fever ticks on cattle:
It was questioned if exposure to any level of rainfall immediately following a dip treatment in coumaphos would reduce the efficacy of the acaricide to levels well below the standard 99% that is considered to be acceptable for use in the eradication program. The level of control provided against cattle exposed to as little as 14.3 mm of rainfall was 83.7% These results clearly demonstrate that rain immediately following a dip reduces efficacy below 99%, emphasizing the necessity of strictly enforcing Rule 41.5 (g) of the Texas Administrative Code, which specifies that cattle may not be moved following a dip treatment in coumaphos if exposure to rainfall results in dip dripping to the ground before the dip dries. Failure to comply with this rule would place the eradication program at great risk of dispersing viable ticks to areas outside of the permanent quarantine zone. (NP104; Component 4; Goal 4.1.1 and Goal 4.1.2)
Development of a geographical information system (GIS) database:
Both historical and current infestation data continue to be entered and updated into our GIS database, and a preponderance of available information is entered and complete for much of the fever tick quarantine zone from Del Rio to Brownsville, TX. We are interacting on a daily basis with Animal and Plant Inspection Service (APHIS) – Veterinary Services (VS) Cattle Fever Tick Eradication Program (CFTEP) personnel to supply them up to date premises maps and associative epidemiological information to aid them in containing the extensive infestations currently included within 2 areas totaling over 1.1 million acres that have been placed under Temporary Preventative Quarantine since July 2007. (NP104; Component 4; 4.1.1)
|Number of Active CRADAs||1|
|Number of New Patent Applications Filed||1|
|Number of Other Technology Transfer||2|
Davey, R.B., Miller, R., George, J.E. 2008. Efficacy of amitraz applied as a dip against an amitraz-resistant strain of Rhipicephalus (Boophilus) microplus (Acari:Ixodidae) infested on cattle. Veterinary Parasitology. 152(1-2):127-135.
Scoles, G.A., Miller, J.A., Foil, L.D. 2008. Comparison of the Efficiency of Biological Transmission of Anaplasma marginale (Rickettsiales: Anaplasmataceae) by Dermacentor andersoni Stiles (Acari: Ixodidae) with Mechanical Transmission by the Horse Fly, Tabanus fuscicostatus Hine (Diptera: Muscidae). Journal of Medical Entomology. 45(1):109-114.
Cantu, A., Ortega-S, J., Mosqueda, J., Garcia-Vazquez, Z., Henke, S.E., George, J.E. 2007. Immunologic and molecular identification of Babesia bovis and Babesia bigemina in free-ranging white-tailed deer in Northern Mexico. Journal of Wildlife Diseases. 43(3):504-507.
Carroll, J.F., Benante, J.P., Klun, J.A., White, C., Debboun, M., Pound, J.M., Dheranetra, W. 2008. Twelve-hour duration testing of cream formulations of three repellents against Amblyomma americanum (Acari: Ixodidae). Medical and Veterinary Entomology. 22:144-151.