- (ENN) -- Clemson University entomologists
are testing the introduction of a naturally-occurring disease into fire
ant colonies as a means to reduce their population growth.
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- The disease keeps fire ant populations
under control in their native South America, but was only recently found
in this country. Without any natural predators, imported fire ants have
run rampant across the southern states and are now spreading to colder
climates.
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- "Using natural means to control
fire ant populations restores balance to the environment," said Mac
Horton, a Clemson entomologist. "Fire ants are having as harsh an
impact on the environment as anything man could do. They dominate many
native plants and animals and cause the natural plant and animal systems
to break down."
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- The ants also have a major economic impact.
Throughout the southern United States, damage estimates are in the billions
as the aggressive ants invade electrical equipment, agricultural fields,
homes and gardens. Their painful sting sends thousands of people to the
doctor each year, and can be deadly for about five out of every 1,000 people.
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- The disease that has been introduced
is carried by a micro-organism, called Theolohania. It reduces the ability
of the queen to lay eggs so the colony slowly dies over a period of six
to eight months.
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- The scientists introduced infected fire
ant larvae into a number of test mounds this summer in South Carolina.
The mounds are being monitored every two months over a two-year period
to track fire ant population activity using satellite technology.
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- Findings will be shared with other states
to generate data across a wide range of climates and conditions, accelerating
the pace of research nationwide.
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- "The disease agent is one of several
strategies that we are testing to control the pests," said James R.
Fischer, director of the South Carolina Agriculture and Forestry Research
System based at Clemson. "Our scientists are also searching for other
environmentally sensitive management strategies, such as competition and
predation by native ants, other potential parasites and predators, and
tests to determine the ecological peculiarities of the ants in North America."
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- The most common method of controlling
fire ants is the use of bait that the ants discover while foraging and
then take back to the colony.
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- "It took 30 years to understand
the biological complexity of fire ants," said Horton. "The adults
use juveniles to convert solid food to liquid food that passes through
several adults before it's given to the queen. They do this to protect
the queen, so we had to develop a very slow-acting bait."
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- Since the queen lays up to 1,000 eggs
a day for as long as seven years, fire ant colonies in South Carolina can
include more than 250,000 ants, compared to fewer than 1,000 for the native
ants. This is one reason why some treatments require several weeks to show
results.
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- When the fire ants detect some pesticides,
they often build a new nest before the treated colony completely dies out.
As a result, Clemson entomologists recommend broadcasting the bait rather
than simply treating the visible mound.
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