An innovative device called a "four-poster" and chemical "tickicides" are two tools Agricultural Research Service scientists are using to protect the southern U.S. border from ticks that carry serious cattle disease.
The southern cattle tick (Boophilus microplus) and the cattle-fever tick (B. annulatus) transmit the two species of blood parasites (Babesia bovis and B. bigemina) that cause the cattle diseases known as cattle fever, Texas fever or bovine babesiosis.
Before their eradication in 1943, tick-carried diseases crippled the U.S. cattle industry. Today, descendants of the ticks that caused those losses can still be found in Mexico. To keep them out, inspectors maintain constant vigilance at the border, preventing infested cattle from entering the United States. But what about wildlife that freely roam?
ARS entomologist Mat Pound and colleagues are investigating strategies for reducing the likelihood that fever-carrying ticks would reappear. They work at the ARS Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, Texas. In 1938, the U.S. Department of Agriculture established a permanent quarantine area, or "buffer zone," in southern Texas - a narrow, 500-mile-long strip along the Rio Grande. For nearly 50 years, the Kerrville lab has provided technical support to this Cattle Fever Tick Eradication Program.
Since the buffer zone was created, the number of cattle tick fever introductions there has varied from year to year. But a significant increase has occurred over the past five years, even in the "tick-free" area north of the buffer zone.
To combat the spread of ticks by wildlife, the Kerrville scientists developed and patented the four-poster device that attracts mostly white-tailed deer - the main secondary hosts for cattle fever ticks in southern Texas - with whole-kernel corn. When a deer feeds, its head and neck brush against pesticide-saturated rollers. Later, when it grooms itself, the pesticide spreads enough to protect its entire body.
Pound and colleagues have tested a permethrin-containing acaricide in the four-poster and are also feeding infested deer whole-kernel corn treated with ivermectin or other systemic acaricides.