INTELLIGENT PEST MANAGEMENT® - ALTERNATIVE CONTROLS OF FIRE ANTS

Fire ants, particularly Red and Black Imported Fire Ants, pose a serious dilemma.  On the one hand, there can be no doubt that the fire ant is a major pest, stinging people, pets and livestock, disfiguring the landscape, even attacking native animals.  In one private preserve, imported fire ants were killing hatchlings of the brown pelican, a threatened species.  On the other hand, aggressive insecticide (poison) treatment of critical habitat can have a greater negative impact on a sensitive environment, and volatile, synthetic insecticide poisons have never proven to really control fire ants anywhere - there generally are more fire ants after an “aggressive” poison campaign than before.  So why use these volatile and useless poisons?

Fire ant management consists of a series of questions and decisions: What fire ant species are in the area?  How extensive is the infestation?  What can be done to control these pests in neighboring areas?  How high is the risk that people, pets or animals will be stung?  How much damage are the fire ants doing?  Is control action justified?  What are the best strategies of control?  Answering these questions requires proper inspection and monitoring to determine the nature and extent of the problem.  You must destroy the queen(s)!

Water Controls - Carefully make a hole in the mound first.

Boiling water has been added to individual fire ant mounds with varying degrees of success reported. Approximately 3 gallons of hot water poured into each mound will eliminate about 60% of the mounds treated. Surviving mounds will need to be treated again. Water has also been applied as steam, using a steam generator, e.g., Vapor Dragon®, usually on a cool day. Both techniques are cumbersome in the field, especially where large numbers of mounds are involved. You can cover the top of the nest with salt and then soak the nest with a sprinkler. We suggest slowly flooding with 3 gallons of diluted Kleen ‘Em Away Naturally® or Safe Solutions, Inc. Enzyme Cleaners (8 oz.) with or without adding 4 -5 tablespoons of Safe Solutions, Inc. food-grade DE, some citrus oils and/or peppermint soap (3 oz.), or try using one gallon of orange/grapefruit juice, 2 gallons of water and a dash of dish soap or peppermint soap or 3 gallons of hot water and ½ cup lye soap on a sunny but cool day - your success rate will greatly improve. Area-wide flooding or prescribed burning of fire ant infested areas has proved ineffective, and may actually promote the establishment of new colonies.

Mechanical Disturbance

Fire ant mounds can be dug up and moved or destroyed, but not without some risk that the fire ants will successfully catch and attack the digger.  Talcum powder dusted on shovels and equipment will help prevent fire ant contact.  Dragging, shallow discing, driving over or repeatedly knocking down fire ant mounds may provide a limited level of control, but only if mounds are dragged or disced, or driven over just before the first hard freeze.  Even tall, hardened mounds can be destroyed by pulling a steel I-beam drag, weighing about a ton, behind a tractor across the fire ant-infested area.  Mechanically disturbing or even destroying fire ant mounds during the warm season will usually not reduce the number of active mounds; ants quickly and simply rebuild them.  Fields that are annually tilled have fewer fire ant mounds than non-tilled fields because of the continuous mechanical disturbance from conventional tillage practices.

A number of mechanical mound pulverizers, ant electrocuters, even nest exploders, have been developed for fire ant control, but so far the effectiveness and practicality of these alternative devices has not been proven.

Electrical Attractants

Electrical fields and/or impulses seem to attract fire ants; use this attraction to lure fire ants to your borax or boric acid baits or talcum powder or traps.  Solar powered yard lights can be adapted to provide electrical current for a field attractant.

Prevention and Sanitation and Habitat Reduction

Remove mulch, food sources, garbage, manure, fruits and nuts, debris, pieces of lumber, old equipment, weeds and grass; elevate bee hives; caulk and seal or fill with aerosol foam insulation all open voids, cracks, crevices; quickly remove dead animals and hay bales; regularly mow and trim and lightly dust with talcum powder or Comet® smear petroleum jelly or Tanglefoot® where you want to keep them out.

Some Biological Controls

A number of biological enemies (pathogens, predators and parasites) of the fire ants have been evaluated as biocontrol agents, including nematodes, bacteria, fungi, viruses, and microsporidia., but biological control has not yet a proven effective control tactic for fire ants. Some show promise, for example, the workerless parasite ant, Solenopsis daguerrrei (Santchi) formerly Labauchena daguerrei was first discovered infecting 1% - 4% of the colonies of the imported fire ant, Solenopsis ricteri (Forel) (formerly Solenopsis saevissima variety ricteri) in Argentina.  This permanent parasite kills the host colony by decapitating the queens. While scarce in South American they (S. daquerrei) might be able to propagate better here as a biological control agent. Phorid flies: There are about 15 species in Brazil and Argentina that attack fire ants there. These (Pseudacteon spp.) Parasitiod flies (Dipteria: Phoridae) all parasitize the red imported fire ant Solenopsis invicta (Buren). There are at least four (4) species P.litoralis, P.wasmanni, P.tricucpic and P.curvatus that have been described. P.curvatus has also been found ovipositing on the native North American fire ant, Solenopsis geminata (F). Sanford Porter, et al, 1997 noted that Pseudaeteon tricuspic (Borgmeier) has been developed successfully on Solenopsis invicta and a hybrid Solenopsis ricteri xs invicta from Mississippi. This fly and its cogener, Pseudacteon litoralis (Borgmeier) have the peculiar habit of decapitating their living host and using the ant’s empty head capsule as a pupal case. The fly takes 4 - 6 weeks to develop from egg to adult. They live only to attack and kill fire ants.

Thelohania. Thelohania solenopsae is a microscopic protozoan (or pathogenic microsporidium) that infects immature and adult fire ants. Diseased ants, including the queens, have shorter life spans and can lay less eggs, so over a period of several months to a year, the colony declines. The pathogen is apparently transmitted by diseased ants moving between multiple-queen colonies. Thelohania attacks only the exotic (or red) and the black imported fire ant and does not attack other ant species native to the U. S.

In Argentina, about 20 percent of the red imported fire ant colonies are infected. Surveys in the U. S. did not detect this disease organism until 1997, when it was discovered in Florida. Since then, Thelohania has also been found in Texas and Mississippi. Research is under way to discover ways to increase the impact of this pathogen and culture it in the laboratory. (Knutson & Drees)

Beauveria. Beauveria bassiana is a common fungus that attacks many species of insects. A strain of Beauveria that attacks the imported fire ant was reported from Brazil in 1987. This fungus produces microscopic spores that attach to the ant’s body, germinate, and grow inside the ant. The fungus feeds on the internal organs of the ant. The ant soon dies, and its body is filled with a fungal growth. The fungus sometimes grows outside the dead ant, covering it with a white, fuzzy growth. Studies have shown that Beauveria applied to the soil is much less effective than if the spores are applied directly to the ants. The application of Beauveria to fire ant baits is being investigated. (Knutson & Drees)

Strepsiptera. Strepsiptera are minute insects that parasitize other insects. One species, Caenocholax fenyesi, attacks the red imported fire ant in the U.S. Like other Strepsiptera, C fenyesi has a complex and unusual life cycle. The female parasitizes a species of bush cricket, Hapithus agitator. Once the immature parasite has consumed the cricket, she develops into the adult stage. However, the adult female never leaves the dead cricket. Rather, she produces thousands of eggs that hatch into larvae called triungulins. The tiny, flattened triungulins leave the female and search for new hosts. While female triungulins must find another bush cricket, male triungulins develop in fire ant adults. Once a male triungulin attaches to a passing fire ant, it burrows into the ant to feed and develop. Parasitized fire ants typically climb to a high perch where they soon die. The adult male Strepsiptera then emerges from the dead fire ant. Only about 1 percent to 2 percent of the fire ants in a colony are parasitized by C fenyesi in Texas. However, Strepsiptera may have potential benefits if inexpensive mass rearing techniques can be developed that provide high numbers for periodic applications. (Knutson & Drees)

Orasema. Species of Orasema (Eucharididae) are tiny wasps that parasitize immature fire ants. Female Orasema wasps lay Iarge numbers of eggs on pIant leaves and buds. The eggs hatch into tiny flattened larvae called planidia. The planidia lie in wait and attach to passing ants. Once in the ant colony the planidia leave the worker ant and attach to ant larvae. When the ant larva pupates, the planidia consumes the ant pupa. Typically, only a small percent of the fire ants are killed by Orasema. Several species of Orasema parasitize the imported fire ant in South America, and several other species of Orasema occur in the U.S. Research is under way to learn more about these ant parasites and to develop mass-rearing techniques.

Nematodes and mites. Certain nematodes (Steinernema spp. and Heterorhabditis species and parasitic mites Pyemotes tritici) also attack and parasitize red imported fire ants, and other insects. Ants in treated colonies often leave the nesting site or mound and move to a new location. However, field evaluations of commercially available species/strains of these parasites currently being marketed for fire ant control have not yet been conducted to demonstrate their effectiveness. (Knutson & Drees)

So far, one of the most effective of these biological controls is a nematode, Neoaplectana carpocapsae. In trials, one application has inactivated about 80% of treated mounds in 90 days. The straw itch mite, Pyemotes tritici, has also been shown to inactivate fire ant mounds. Three to ten applications at about two week intervals gave 70% control. Practical use of this mite for fire ant control must await the development of more efficient methods of mass production and increased effectiveness. Another problem is that this mite is a pest of people and animals; it bites and a causes dermatitis. It is thought the phorid flies only parasitize 1% - 3% of the fire ant colony, but the ant behavior is far more important, the fire ant workers quickly learn to escape underground or assume a defensive poisition and only 3 - 4 flies are needed to disrupt normal ant activity.

Ant-Proofing

Fire ants, like other ants, may be nesting near buildings and can enter and move through a structure through innumerable tiny cracks and openings. Caulking and foaming with aerosol insulation or otherwise sealing cracks and crevices and areas being used by fire ants can often have great effect in suppressing the population inside. If it is not safe or possible to caulk and/or to foam, dust with talcum or medicated body powder or food- grade DE. Many effective, easy-to-use silicon sealers or caulks and expandable aerosol foam insulation products have been recently developed, including some designed specifically for pest management.

Public Education

The most effective measure for preventing fire ant injury to people is education.  Activities should be directed away from highly infested fire ant areas.  People should be informed about the habits of fire ants, how to recognize them, and how to avoid them.  People should be encouraged to use proper sanitation so that fire ants are not attracted to such sites as picnic areas.  And if the worst happens, information should be available on what to do if a person is stung.

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