The sting of the red imported fire ant (Solenopsis invicta Buren) possesses venom of an alkaloid nature, which exhibits potent necrotoxic activity. Approximately 95% of the venom is composed of these alkaloids, which are responsible for both the pain…
Red Fire Ant
Red Fire Ant
Common name: Red imported fire ant.
Scientific name: Solenopsis invicta Buren
(Insecta: Hymenoptera: Formicidae: Myrmicinae)
Worker Red Fire Ant | Mtazamo.Photography (Penang, Malaysia, Sep 2021)An extreme pest in my home garden. I’ve been sting many times. The pain, swelling and bruising, an experience I wish on no one.
Worker Red Fire Ant
The worker red fire ant has been a continuing problem for me as a home Gardner in Penang, Malaysia. I’ve been bit/stung several times by this aggressive predator. The affected area requires immediate attention with the application of a particular balm to lessen pain and reduce swelling.
Introduction
The red imported fire ant is native to central South America. It is also established in the U.S. and Australia (Queensland, near Brisbane – as of 2001) (Shattuck and Barnett 2005).
It has been reported in Antigua and Barbuda, Bahamas, the British and U.S. Virgin Islands, Cayman Islands, Hong Kong, Malaysia, Singapore, Taiwan, Trinidad and Tobago, and the Turks and Caicos Islands (ISSG 2006).
Populations in New Zealand and mainland China are either currently eradicated (N.Z.) or undergoing eradication (China) (ISSG 2006).
Head of Worker Ant
Head of a worker of the red imported fire ant, Solenopsis invicta Buren. Photograph by David Almquist, University of Florida.
Sting
The sting of the red imported fire ant possesses venom of an alkaloid nature, which exhibits potent necrotoxic activity. Approximately 95% of the venom is composed of these alkaloids, which are responsible for both the pain and white pustule that appears approximately one day after the sting occurs. The remainder of the venom contains an aqueous solution of proteins, peptides, and other small molecules that produce the allergic reaction in hypersensitive individuals. Worker fire ants will attach to the skin using their mandibles and will subsequently lower the tip of the gaster to inject the stinger into the victim. Thus, fire ants both bite and sting, but only the sting is responsible for the pain and pustule (Goddard 1996).
Human Toll
The human toll from red imported fire ant stings is an important public health concern. Stings may produce a large range of reactions from localized pain and swelling to anaphylactic shock, making it hard to estimate the cost to public health.
Diet
The diet of foraging workers consists of dead animals, including insects, earthworms, and vertebrates. Workers also collect honeydew and will forage for sweets, proteins, and fats in homes. They are sometimes attracted to piles of dirty laundry. Larvae are fed only a liquid diet until they reach the third instar. When the larvae reach the fourth instar, they are able to digest solid foods. Worker ants will bring solid food rich in protein and deposit it in a depression in front of the mouth of the larvae. The larvae will secrete digestive enzymes that break down the solid food and regurgitate it back to worker ants. The queen is fed some of the digested protein to support egg production. As long as food is plentiful, egg production is at its maximum (Vinson and Sorenson 1986).
Urban Settings
In urban settings, the red imported fire ant may nest under patio slabs, in lawns, under edges of sidewalks, foundations, concrete driveways, and electrical boxes. After a heavy rain, the colony may move to higher ground or inside homes to take refuge from saturated soil. If nesting under patio slabs or concrete walkways, the nest cavity may cause the concrete slab to fall and cause damage to the sidewalk (Vinson and Sorenson 1986).
Ground-nesting Populations
Red imported fire ants have been reported to reduce ground-nesting populations of rodents and birds. In certain instances, the red imported fire ant may completely eliminate ground-nesting species from a given area (Vinson and Sorenson 1986). Because there is a 10 to 20 year lapse before reductions in bird populations are observed, it has been suggested that actual effects of the red imported fire ant on animal populations may be underestimated (Mount 1981).
Aenean lacinia bibendum nulla
Pest Management
Fire ants frequently invade home lawns, school yards, athletic fields, golf courses, parks and other recreational areas. Additionally, electrical equipment and utility housing, home gardens, compost piles, mulched flowerbeds, pavement cracks, and the perimeter of bodies of water must all be considered when choosing a method of control.
Two approaches can be taken to effectively manage imported fire ants. Single mound treatments or area-wide broadcast applications usually manage red imported fire ant populations.
(Note: Text adapted from several sources.)
Taxonomy
Originally, Solenopsis invicta was believed to be a red form of the black species Solenopsis saevissima richteri Forel. In 1972, Buren described the black imported fire ant to be a separate and distinct species, Solenopsis richteri Forel, and the RIFA was identified as Solenopsis invicta Buren (Hedges 1997). Literature dated earlier than 1972 referring to the biology and control of “Solenopsis saevissima richteri” almost exclusively refers to Solenopsis invicta (Ebeling 1975). Some literature found may contain the name Solenopsis wagneri, which refers to Solenopsis invicta (Shattuck et al. 1999).
My home garden in Penang, Malaysia, Sep 2021
Individual Mound Treatments
There are many methods of treating individual mounds. The main advantage to this process is that there are so many choices available to homeowners and pest control operators, though few may actually eliminate the colony. However, the largest disadvantage is that individual mounds must each be located in order to be treated. Individual mound treatments are most beneficial when there are native ants in the same area as imported fire ants. Reinfestation of any treated area, whether by broadcast treatment or individual mound treatment may occur. Six methods of individual mound treatment are available (Vinson and Sorenson 1986).
Mound Drenches. Large volumes of liquid toxic to ants are poured over a mound. Liquids can range from using several gallons of hot water to insecticides mixed with several gallons of water. This method may not reach the queen, which may be deep in the nest, thus preventing colony elimination.
Surface Dusts. This method is very similar to mound drenches. A dust or granular insecticide is applied over the top of the mound and then watered into the soil.
Mound Injections. The use of insecticides that may be pressurized and injected into a mound. Often this method is more expensive, but more effective, than mound drenches; however, more time may be required for this method and leakage of the insecticide by the equipment may be hazardous to the handler. Again, the queen may not be affected and thus reinfestation may occur.
Baits. Baits can be used for both individual mound and broadcast applications. A small amount of the bait is sprinkled around the mound and the ants then forage and bring the bait back to the colony to feed on. This method is slower acting, but more effective then drenching, dusting, or fumigating a mound because the workers will feed the bait to the queen and brood, thus gaining effective control of the colony.
Mechanical Control. Certain mechanical and electrical devices are on the market for controlling fire ants, but the efficacy has not been documented (Vinson and Sorenson 1986).
Home Remedies. Many homeowners will choose to pour boiling water or ignite flammable liquids over a mound. While these methods may bring about control, they are not recommended because they are both very dangerous, not only to humans, but also to the environment.
Broadcast Treatments
Currently, there are only a few products available for broadcast treatment of large areas. These products are either granular insecticides or baits composed of soybean oil and toxicant on a corn grit carrier. These granules are broadcast over a large area and, upon discovery by the ants, are carried to the colony and fed to nestmates and the queen. This is a very effective treatment but does present problems because (1) some of the bait may be dropped where the ants may not find it, (2) some colonies are well fed so do not feed upon the bait, (3) some baits are light sensitive (as with hydramethylnon) and may inactivate before discovery by the ants, and (4) the baits are not specific to the imported fire ant (Vinson and Sorenson 1986).
Worker Red Ant Video |Sep 2021
Note: All images/videos taken with iPhone 12 Pro Max
using Sandmarc Macro len’s, except others as noted.
Biological Control
Current research is leading the way for introduction of natural enemies of the red imported fire ant. Two hopeful pathogens are the microsporidian protozoan Thelohania solenopsae and the fungus Beauveria bassiana. Two parasitoid flies from South America, Pseudacteon tricuspis and Pseudacteon curvatus have been introduced into the southern states. These flies decapitate worker ants in the final stages of larval development. In addition, a parasitic ant, Solenopsis daguerri (Santschi) which invades fire ant colonies and replaces the queen to take control of the colony, is being investigated for another possible biological control agent of the red imported fire ant.
Worker red ant seen repeating a peculiar pattern of behaviour.
Spotlights
Natural Enemies Close In on Fire Ants (Sep 9, 2019) (external link)
USDA. ARS. Tellus.
Hunting for natural enemies of the red imported fire ant is paying off for Agricultural Research Service (ARS) scientists. Their latest discovery — a new virus found in fire ants from Argentina — has the potential of becoming a biological control agent against the red imported fire ants infesting the U.S.
What Happens to Fire Ants During a Flood? (external link).
If a fire ant colony is flooded during a rainstorm or other high-water situation, the ants cling together and form a living raft that floats on the flood waters. Once the raft hits dry ground or a tree, rock, or other dry object, the ants can leave the water.
Footage Shows Massive Colonies of Fire Ants Floating in Hurricane Florence Floodwater (Sep 18, 2018). (external link)
AOL News.
Floodwaters will not drown fire ants. In the wake of Hurricane Florence, victims in the storm’s path are being warned to avoid wading through dangerous floodwaters (in addition to other reasons and threats).
