Newly
mated fire ant queens, which can start new colonies, are killed
by a number of organisms. These include birds, lizards, spiders,
toads, dragonflies, robber flies, other ant species and fire
ants from surrounding colonies. Animals that eat ants such
as armadillos may disturb mounds to eat some workers, but
they are not really useful in control.
Currently,
the best biological control method for fire ants is to preserve
native and exotic ant species that compete with them for food
and nesting sites, attack small fire ant colonies or kill
newly-mated queen ants. Ants, in general, are considered to
be beneficial insects because they prey on many other arthropods
and collectively till more earth than earth worms, thereby
reducing soil competition. One way to preserve native ants
is the judicious use of insecticides and habitat preservation.
 
Introduction,
establishment and conservation of natural enemies (diseases,
parasites and predators) of imported fire ants can result
in sustainable suppression wither by reducing population levels
directly or by rendering the ant less fit for survival relative
to to competitor ant species that occur in these states. The
most effective biological control organisms for large-scale
programs will likely be those that spread by themselves from
mound to mound and persist from year to year. Three species
of parasitic "phorid" flies in the family Phoridae,
have been released and established in parts of most southeastern
stats, including Pseudacteon tricuspis, P. curvatus, and
most recently, P. litoralis. A disease of fire ants, Thelohania
solenopsae, is also wide spread in some states. As these
and other natural enemies of imported fire ants are established
and maintained, collectively they are expected to reduce the
fitness of these exotic pest relative to competitor ant species.
Several years may be required to document any effect of the
released fly species on fire ant populations levels, Although
natural enemies will not eliminate fire ants, it is hoped
that introducing natural enemies of fires ants in the U.S.
will reduce their population levels indefinitely as in South
America, the home of imported fire ants, where they are not
considered to be a pest but rather "just another ant."
The
microorganism, Thelohania solenopsae, and parasitic phorid
flies, Pseudacteon spp., also known as decapitating flies,
have been introduced in Tennessee as biological control agents
for imported fire ants. Thelohania has been most successful
in areas of the southern United States where multiple-queen
fire ant colonies occur. Our lack of multiple-queen fire ant
colonies in Tennessee may explain its failure to establish
here. In 2004, Pseudacteon curvatus was found in over 20 Tennessee
counties. Not only do parasitized ants loose their heads and
die, but the fly also disrupts the foraging of other workers.
This may weaken the colony from diminished food returns. For
up-to-date information on the use of these biological control
organisms see The
USDA Area Wide Fire Ant Suppression Program web
site.
Another
biological control for fire ants is the preservation of native
and exotic ant species that compete with them for food and
nesting sites, attack small fire ant colonies or kill newly-mated
queen ants. One way to preserve native ants is the judicious
use of insecticides.
 
 
 
Images from K. Vail UT E&PP, R. Pereira
and Sanford Porter USDA
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