Submitted to: Southern Association of Agricultural Scientists Bulletin of Biochemistry and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 19, 2004
Publication Date: February 1, 2005
Citation: Temeyer, K.B., Pound, J.M., Miller, J.A., Chen, A.C., Pruett Jr, J.H., Guerrero, F., Davey, R.B., Untalan, P.M., Lohmeyer, K.H., Li, A.Y., Miller, R., George, J.E. 2004. Organophosphate resistance in Mexican strains of Boophilus microplus: A major threat to the U.S. cattle industry. Southern Association of Agricultural Scientists Bulletin of Biochemistry and Biotechnology. 17:43-51. Interpretive Summary: Mexican strains of cattle fever ticks are a threat to the U.S. Cattle industry because they transmit an often fatal disease of cattle endemic in Mexico, to which U.S. cattle have no resistance. Cattle fever ticks were eliminated from the United States after a costly eradication program that spanned half a century, but are still common in Mexico. Each year, U.S. cattlemen import approx. 1 million cattle from Mexico. Imported cattle must be treated with pesticides, inspected by U.S. animal health agents and dipped in coumaphos, an organophosphorus pesticide, to kill any ticks that may have been missed during the inspection, before being allowed entry into the United States. The inspection and eradication program has prevented cattle fever ticks from becoming reestablished in the southern United States for the last 60 years and is estimated to have saved the U.S. cattle industry over a billion dollars per year. U.S. Department of Agriculture scientists have worked to help Veterinary Services keep the cattle fever ticks out of the U.S., however, Mexican strains of the cattle fever ticks have developed resistance to pesticides, including the coumaphos used in the dipping vats at the border. Recent studies strongly suggest that current methods to keep the ticks out of the U.S. are in danger of failure because some Mexican cattle fever ticks have become so resistant to coumaphos that they may survive the dipping procedure and obtain entry into the United States. The risk to the U.S. cattle industry is substantial and immediate. Additional funding for research is urgently needed.
Technical Abstract: Mexican strains of Boophilus microplus that are highly resistant to coumaphos, an organophosphate pesticide, constitute a major threat to the U.S. Cattle industry. The most resistant strain studied to date has been demonstrated to survive the dipping procedure used at the border as part of an import barrier to prevent the reentry of B. microplus into the United States. B. microplus was eradicated from the United States in 1943 through the Cattle Fever Tick Eradication Program begun in 1906. B. microplus is a vector for babesiosis, an often fatal disease of cattle endemic in Mexico, for which U.S. cattle have no resistance. This report summarizes research to identify and characterize mechanisms of acaricide resistance in B. microplus and the development of new technologies to control B. microplus in alternative hosts. The potential for acaricide-resistant strains of B. microplus to breach the import barrier identifies a serious outbreak of cattle fever ticks as a strong possibility. Eradication of a widespread outbreak could be greatly hampered by acaricide resistance, rapid transportation of tick-infested animals, the presence of increased wildlife populations potentially capable of serving as alternative hosts, and improved favorability of microhabitat for B. microplus survival. There is a strong and urgent need for application of recent advances in molecular genetics and proteomics to B. microplus to enable development of new control technologies.