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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGY AND CONTROL OF TICKS OF VETERINARY AND HUMAN IMPORTANCE

Location: Tick and Biting Fly Research

Title: Spatiotemporal Incidence of Acaracide Resistance among Outbreaks of Cattle Fever Ticks in the US

Authors
item Thomas, Donald
item Miller, Robert
item Pound, Joe
item Tidwell, Jason
item Kammlah, Diane
item Olafson, Pia
item Perez De Leon, Adalberto

Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 30, 2013
Publication Date: N/A

Interpretive Summary: Cattle fever ticks were exterminated from the U.S.A. but are still encountered along the border with Mexico. The USDA maintains a quarantine buffer zone with surveillance for stray Mexican cattle and inspection of herds in the counties along the Rio Grande. The year 2008, a rainy "El Nino" year, was the worst in decades in terms of the number of fever tick outbreaks with 148 separate premises infested. With the prevalance of severe drought in the years since, the numbers of outbreaks have sharply declined, to only 48 in 2012. Unfortunately, while the number of outbreaks has declined, the ticks are showing a tendency to survive insecticide applications. In 2008 only 11% of the outbreaks had any survival to treatments. In 2012 one third of the outbreaks showed some level of survival. Moreover, the ticks have been able to survive a variety of different classes of insecticide. Development of a strategy for managing tick resistance against insecticides is now a major focus of the program.

Technical Abstract: Cattle fever ticks, Rhipicephalus (Boophilus) spp, were eradicated from the U.S. but regularly make incursions along the border with Mexico. The USDA maintains a quarantine buffer zone with surveillance for stray Mexican cattle and inspection of herds in the counties along the Rio Grande. The year 2008, a peak "El Nino" oscillation year, was the worst in decades in terms of the number of fever tick outbreaks with 148 separate premises infested. With the prevalance of severe drought in the years since, the numbers of outbreaks have sharply declined, to only 48 in 2012. Unfortunately, while the number of outbreaks has declined, the incidence of Acaricide resistance among the ticks has increased. In 2008 only 11% of the outbreaks had significant levels of resistance. In 2012 one third of the outbreaks showed some level of resistance. And whereas the resistance detected in 2008 was to synthetic pyrethroids, in recent years resistance to Amitraz and organophosphates has also manifested. Interception of these ticks and development of a strategy for managing resistance is now a major focus of the Cattle Fever Tick quarantine program.

Last Modified: 8/27/2014
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