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Title: Influence of acaricide resistance in Mexican Rhipicephalus (Bophilus) microplus on the importation of cattle to the USA

item Miller, Robert

Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/6/2010
Publication Date: 5/26/2010
Citation: Miller, R. 2010. Influence of acaricide resistance in Mexican Rhipicephalus (Bophilus) microplus on the importation of cattle to the USA. Symposium Proceedings. 1: 44-49.

Interpretive Summary: Pesticide resistance in the southern cattle tick (Boophilus microplus) has been on the rise in Mexico since the 1980’s. Because this tick was eradicated from the United States, it is important to inspect and treat with pesticide all Mexican cattle bound for importation into the United States for ticks. Pesticide resistant ticks increase the risk of re-infestation of the United States because ticks may survive chemical treatment during the importation process. This manuscript presented the current importation statistics and potential impacts to Mexican exporters that pesticide resistant ticks could have on the exportation of Mexican cattle to the United States. This work provided Mexican scientists, producers, and exporters with the information needed to understand the difficulties likely to be encountered if resistant ticks are present on cattle bound to importation to the United States. This work will lead to discussion and hopefully the development of rational pesticide management practices in Mexico to control the development of pesticide resistance in southern cattle ticks and in turn reduce the risk of re-infestation of the United States by the importation of Mexican cattle.

Technical Abstract: The southern cattle tick, Boophilus microplus, is a pest of cattle that was eradicated from the United States through an eradication campaign administered by the U.S. Department of Agriculture. The continuous enforcement of the Cattle Fever Tick Eradication Program (CFTEP) of APHIS, VS saves the U.S. Cattle industry over a billion dollars per year. The money saved is one factor that keeps the consumer price for meat low in the U.S. The success of this CFTEP relies heavily on the successful use of pesticides. An area along the Texas-Mexico border is continuously infested with cattle ticks. This area is called the Cattle Fever Tick Quarantine Zone. Tick inspectors employed by the USDA continuously inspect native cattle in this zone for ticks and also search for stray cattle that may have wandered to the U.S. from Mexico. When ticks are found on cattle, the area is quarantined and all the cattle are treated with pesticide to kill the ticks. In Mexico, the cattle tick problem is managed rather than eradicated. Management is usually pesticide based and as a consequence many cattle tick populations have developed resistance to the modern pesticides over the last 25 years. Resistant ticks create problems for Mexican ranchers, because newer pesticides to which resistance has not developed are expensive. Additionally, cattle must be free of ticks if they are to be imported to the U.S. for sale. In 2004, two populations of pesticide resistant ticks, resistant to two different types of pesticide, were collected in Texas for the first time. Fortunately, these populations were not highly resistant and the high concentrations of pesticide used by the USDA were sufficient to eradicate them. However, the discovery of resistant ticks within the U.S. border represents a serious threat to the integrity of the CFTEP. Resistant ticks in Mexico increases the need for vigilance on the part of U.S. inspectors and Mexican importers. In the future it will become more difficult for importers to clear cattle of tick infestation with acaricides which will likely create delays and increase the overhead cost of importation.