2009 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 accomplished during the five years of this project has contributed significantly toward meeting the objectives. Eradication procedures of the APHIS Cattle Fever Tick Eradication Program were evaluated and suggestions were made regarding acaricide treatment of cattle, white-tailed deer, and exotic ungulates. New acaricides were evaluated to treat cattle, and an injectable macrocyclic lactone formulation was evaluated and field-tested that would reduce the number of gatherings and treatments of cattle by half as compared with the standard treatment. Among other technologies developed to control fever ticks feeding on white-tailed deer, to reduce costs of controlling fever ticks on deer ARS developed and commercialized the '2-Poster' Feeder Adapter that can be attached to deer feeders, permitting the same feeder to dispense the medicated bait and to apply topical acaricide. ARS continued to enter data into the GIS database and into other databases of current and historical eradication intervention efforts. ARS queried the databases and constructed, printed, and provided APHIS with detailed maps of infested, adjacent, and other regulated premises, and also provided geo-spatial boundary maps and summary spatial data of Temporary Preventative Quarantines when they were established and defined by the Texas Animal Health Commission.
Tests demonstrate resistance of U.S. cattle fever ticks to acaricides: There is much concern that acaricide-resistant cattle fever ticks may enter the U.S. from Mexico and compromise efforts to maintain eradication of these ticks from cattle herds in the U.S. Routine bioassays were used to evaluate 68 strains of cattle fever ticks; and of these, four strains were highly resistant to pyrethroid acaricides (permethrin) and five strains showed a low resistance to the organophosphate acaricide coumaphos. It was determined that the coumaphos-resistant strains could be killed by dipping cattle twice rather than only once. However the permethrin-resistant strains are problems because white-tailed deer cannot be gathered and dipped, and to kill fever ticks feeding on them, only a single formulation of permethrin is available for use on them during hunting season. Therefore, because fever ticks that were highly resistant to permethrin were found on white-tailed deer, ARS is working with industry to develop, register, and make commercially available non-pyrethroid topical acaricides to be topically applied to deer with the ARS-patented '4-Poster' Deer Treatment Bait Stations and newly developed '2-Poster' Deer Treatment Feeder Adapters.
Long-acting acaricide has less than labeled protection from fever tick re-infestation: Current regulations require that cattle fever tick infested cattle that are to be treated for ticks must be gathered and dipped in coumaphos every 14 days for either 6- or 9-month quarantine periods. To reduce the number of treatments, ARS is evaluating long-lasting acaricides that have extended periods of efficacy as alternative acaricides to use in the eradication program. ARS demonstrated that a single injection with a long-acting formulation of ivermectin provided greater than 99.9% control of southern cattle ticks that were feeding on cattle at the time of treatment. However, the acaricide did not provide protection for 75 days that is listed on the label. Results indicated that it would be possible to extend the treatment interval of tick-infested cattle to 30 days without risk of dispersing viable ticks to un-infested areas. Nevertheless, this interval of 30 days would significantly reduce the number of gatherings and thus reduce the cost to ranchers who presently must treat cattle in fever-tick-infested premises every 14 days.
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George, J.E. 2008. The effects of global change on the threat of exotic arthropods and arthropod-borne pathogens to livestock in the United States. Annals of the New York Academy of Sciences. 1149:249-254.
Davey, R.B., Miller, J.A., Miller, R., George, J.E. 2009. Effect of rainfall exposure immediately after a single dip treatment with coumaphos on the control of Rhipicephalus (Boophilus) microplus (Acari:Ixodidae) on infested cattle. Journal of Medical Entomology. 46(1):93-99.
George, J.E., Pound, J.M., Davey, R.B. 2008. Acaricides for controlling ticks on cattle and the problem of acaricide resistance. In: Bowman, A.S., Nuttall, P., editors. Ticks Biology, Disease and Control. Cambridge, New York:Cambridge University Press. p. 408-423.
Mougeot, F., Moseley, M., Leckie, F., Martinez-Padilla, J., Miller, A., Pound, J.M., Irvine, R. 2008. Reducing tick burdens on chicks by treating breeding female grouse with permethrin. Journal of Wildlife Management. 72(2):468-472.
Lohmeyer, K.H., Miller, J.A., Pound, J.M., Oehler, D.D. 2009. Efficacy of Eprinomectin and Doramectin against Amblyomma americanum (Acari:Ixodidae)on cattle. Journal of Economic Entomology. 102(2):809-814.
Carroll, J.F., Pound, J.M., Miller, J.A., Kramer, M.H. 2008. Reduced interference by gray squirrels with 4-poster deer treatment bait stations by using timed-release bait. Journal of Medical Entomology. 33(2):325-332.
Pound, J.M., Miller, J.A., George, J.E., Fish, D. 2009. The United States Department of Agriculture northeast area-wide tick control project - history and protocol. Vector-Borne and Zoonotic Diseases. 9(4):365-370.
Pound, J.M., Miller, J.A., George, J.E., Fish, D., Carroll, J.F., Schulze, T.R., Daniels, T.J., Falco, R.C., Stafford III, K.C., Mather, T.N. 2009. The United States Department of Agriculture's northeast area-wide tick control project - summary and conclusions. Vector-Borne and Zoonotic Diseases. 9(4):439-447.