Microbes Clean Up Cattle Dip
Filled with 5,000 gallons of water and tick-killing coumaphos,
dipping vats like this one eliminate ticks on more than a million herd of
cattle each year. Disposing of waste insecticide has become easier since ARS
microbiologist Jeffrey S. Karns founds ways to speed up microbial conversion to
carbon dioxide and water.
A million Mexican cattle a year scramble into the United States through
concrete vats placed on the Mexican side of major border crossings.
The vatsmore like concrete chuteseach hold 5,000 gallons of
tick-killing coumaphos and water. The cattle jump into dip that is over their
heads and then swim a little before the ramp bottom rises enough to allow them
to walk out the other end.
The dip in each vat has to be changed at least every 2 years and in many
cases more often. So what do you do with 100,000 gallons of used pesticide dip
generated every year?
Jeffrey S. Karns, an ARS microbiologist in Beltsville, Maryland, found that
the coumaphos insecticide in waste dip can be converted to carbon dioxide and
water, with a little encouragement to some microbes that live in the dip.
By adding iron and magnesium salts and other nutrients to function like
vitamins for these microbes and by carefully adjusting the dip's acidity and
oxygen content, Karns has gotten the microbes to oxidize unwanted components in
just a week or two.
The technique works just as well on soil contaminated by dip disposal, says
Karns works on the project with ARS microbiologists Walter W. Mulbry and
Daniel R. Shelton, who are also at Beltsville.
So why is all this dipping being done? In addition to the tick-prevention
measures at the border, American ranchers use 42 vats scattered along the U.S.
side of the border to treat cattle whenever a tick outbreak occurs. These
outbreaks are often due to infested deer or cows wading across the Rio Grande.
Since 1935, USDA tick eradication program officials have been supervising
the operation of vats on both sides of the Texas-Mexico border in a
500-mile-long strip of land along it. This quarantine zone is the only part of
the United States where cattle fever ticks are found.
It is also a zone of constant vigilance: Cattle are not allowed to leave
without treatment. That keeps ticks from entering the United States from
Mexico, where the tick remains prevalentdespite some 3,000 vats for
Mexican ranchers' use.
USDA's Animal and Plant Health Inspection Service oversees the tick
eradication program, in cooperation with the state of Texas. Entomologists
Elmer H. Ahrens and Ronald B. Davey, who are at the ARS Cattle Fever Tick
Research Laboratory in Mission, Texas, send samples from the vats to Beltsville
The dipping is necessary to prevent the reintroduction of cattle fever to
the United States. Cattle fever once nearly destroyed the southern cattle
industry because few northerners wanted to risk buying tick-infested cattle. It
cost the cattle industry over $1 billion a year in losses and reduced
production before the tick's eradication outside of the quarantine zone, in
1943. -- By Don Comis, ARS.
Shelton is at the USDA-ARS
Microbial Safety Laboratory, Bldg. 007, 10300 Baltimore Ave., Beltsville,
MD 20705; phone (301) 504-6582, fax (301) 504-6608.
Karns is at the USDA-ARS
Microbial Safety Laboratory and
W. Mulbry is at the ARS
Manure & By-Products Laboratory, 10300 Baltimore Ave., Beltsville, MD
"Microbes Clean Up Cattle Dip" was published
in the April 1995
issue of Agricultural Research magazine.