Fire ant Insecticides, Modes of Action and Formulations with Generic Names of Active Ingredients and Examples of Product Names

Imported Fire Ants February 25, 2015 Print Friendly and PDF

Baits

Hydramethylnon - (Amdro® Fire Ant Bait, Amdro®Pro Fire Ant Bait, MaxForce® Complete, Probait® and others)
This ingredient kill ants by preventing them from converting food into energy. These baits eliminate fire ant colonies within a week when applied to individual mounds, but take several weeks when broadcast. They are also formulated in bait granules and stations.

Avermectins (abamectin) - (Ascend™, Award® II, Optigard™ Fire Ant Bait)
This bait product is derived from a soil fungus and inhibits nerve transmission. As a mound treatment it kills worker ants and colonies quickly, but as a broadcast treatment it acts more like an insect growth regulator, preventing the production of viable eggs. Formulations include bait granules and stations.

Oxadiazine (indoxacarb) - (Advion® Fire Ant Bait)
This class of insecticides has a unique mode of action. Indoxacarb undergoes bio-conversion in the insect to a more toxic form. When ingested it irreversibly blocks sodium channels in nerve cells, resulting in paralysis and death. The compound is quick-acting and controls ants in 3 to 14 days even when broadcast.

Semicarbazone (metaflumizone) - (Altrevin™, Siesta™)
Metaflumizone blocks the sodium channel of the nervous system causing “relaxed” paralysis of insect.No known cross-tolerance by insect strains resistant to carbamates, OPs, pyrethroids, or benzoylureas. No metabolism of insecticide required for toxicity to target insects. This compound has the ability to eliminate fire ant activity in as few as seven days.

Spinosyns (spinosad) - (Ferti-lome® Come and Get It, Pay Back Fire Ant Bait))
Spinosad, which includes spinosyn A and spinosyn D, is derived through the fermentation of a naturally occurring organism. These insecticides have a unique mode of action that is different from all other known insect control products. Spinosad causes excitation of the insect nervous system, leading to involuntary muscle contractions, prostration with tremors, and finally paralysis. These nerve toxin effects are consistent with the activation of nicotinic acetylcholine receptors by a mechanism that is novel and unique among known insecticidal compounds.

Phenyl pyrazole (fipronil) - (MaxForce® FC)
As a nervous system toxicant, it blocks the passage of chlorine ions by interacting with gamma-aminobuteric acid (GABA)-gated chloride channels on nerve cell membranes. A bait formulation is available for broadcast or individual mound treatment. Broadcast application provides maximum control 6 to 12 weeks after treatment. Formulations include bait granules and stations.

Insect growth regulators (methoprene, pyriproxyfen or 2-[1-methyl-2(4-phenoxyphenoxy) ethoxyl] pyridine) - (Extinguish®, Distance® Fire Ant Bait, Esteem® Ant Bait)
These materials mimic the effects of the insect’s own juvenile hormone, reducing the production of viable eggs and preventing the development of worker ants for up to a year after application. They do not kill adult ants, but render winged female reproductives developing after treatment sterile. Treated ant colonies persist for several months after treatment, until worker ants present at the time of treatment die naturally. Ants do not die faster when more product is applied than directed. These products are formulated as baits to be applied to individual mounds or broadcast.

Product mixtures: Hydramethylnon plus methoprene
The “hopper blend” (directions are on the Amdro®Pro and Extinguish® labels) is both fast acting like hydramethylnon and long lasting like methoprene. It is available as pre-blended products, Extinguish® Plus and Amdro® FireStrike Fire Ant Bait.

Contact Insecticides

Botanicals (d-limonene, pyrethrins, rotenone, pine oil, cedar oil, turpentine) - The citrus or orange oil component, d-limonene, is a cytotoxin that kills cells after entering the insect body through direct contact. Other essential oils or components of essential oils have come on the market in the last few years in a variety of pesticides. Essential oils are volatile, highly concentrated substances extracted from plant parts, including the oils of cedar, cinnamon, citronella, citrus, clove, eugenol (a component of clove oil), garlic, mints, rosemary, and several others. As insecticides, they vary in their modes of action, but most work as contact killing agents only, so re-treatment may be needed. Some are promoted as repellents. Some essential oils used as pesticides may work by disrupting an insect neurotransmitter that is reported to be not present in people, pets, or other vertebrates. Most of these ingredients are generally regarded as safe for mammals by the United States Food and Drug Administration when used as directed. Many are even used extensively as flavorings and scents in foods, cosmetics, soaps, and perfumes. Pyrethrum is the source of natural insecticides made from the ground dried flowers of certain species of a chrysanthemum plant. The ground flowers contain a mixture of several different compounds called pyrethrins and cinerins. Pyrethrins are natural insecticidal compounds that are extracts of the chrysanthemum plant. Pyrethroid insecticides, such as permethrin, bifenthrin, cypermethrin and others, are synthetic versions of this naturally occurring insecticide. Pyrethrins, like pyrethroid insecticides, bind to sodium channels that occur along the length of nerve cells. Sodium channels are responsible for nerve signal transmission along the length of the nerve cell by permitting the flux of sodium ions. When pyrethrins bind to sodium channels, normal function of the channels is obstructed thereby resulting in overexitation of the nerve cell and, consequently, a loss of function of the nerve cell. Pyrethrins are often combined with diatomaceous earth (see inorganic compounds below). Rotenone acts on respiratory tissues, nerves and muscles. Pyrethrins and rotenone products break down rapidly in the environment. Rotenone, cedar oil and pine oil (turpentine) products are relatively slow-acting (days to weeks) and are applied as mound drenches.

Derivatives of pyrethrins (allethrin, resmethrin, sumithrin, tetramethrin) - Like pyrethrins, these products destabilize nerve cell membranes and kill quickly, but are quickly deactivated and have little residual activity. They are contact insecticides applied as aerosol injections, mound drenches or surface sprays.

Pyrethroids (bifenthrin, cyfluthrin, cypermethrin, deltamethrin, fenvalerate, fluvalinate, lambda-cyhalothrin, permethrin, s-bioallethrin, es-fenvalerate, tefluthrin, tralomethrin) - These products also destabilize nerve cell membranes. They can persist in the environment longer than pyrethrins and their derivatives. They kill ants relatively quickly and are applied as mound drenches, dusts, surface sprays or granules.

Carbamates (carbaryl) - These materials disrupt nerve transmission (cholinesterase inhibitor). They are relatively quick-killing contact insecticides used as mound drenches, soil treatments and surface sprays.

Organophosphates (acephate) - These products also interfere with nerve cell transmission (cholinesterase inhibitor). They are relatively quick-killing and are formulated as aerosols, liquids, dusts or granules. They can be applied as mound treatments or surface treatment.

Note: Diazinon and Dursban® (chlorpyrifos) products have been phased out for many uses, particularly homeowner uses, and are no longer being sold. Dursban® (chlorpyrifos) is still available for imported fire ant quarantine uses. Use any remaining stored product as directed on the label for homeowner uses, or contact local or state hazardous waste disposal programs for disposal instructions.

Spinosyns (spinosad) - Spinosad, which includes spinosyn A and spinosyn D, is derived through the fermentation of a naturally occurring organism. These insecticides have a unique mode of action that is different from all other known insect control products. Spinosad causes excitation of the insect nervous system, leading to involuntary muscle contractions, prostration with tremors, and finally paralysis. These nerve toxin effects are consistent with the activation of nicotinic acetylcholine receptors by a mechanism that is novel and unique among known insecticidal compounds. Several of the spinosad liquid products have fire ant mound drench instructions on label.

Phenyl pyrazole (fipronil) -  As a nervous system toxicant, fipronil blocks the passage of chlorine ions by interacting with gamma-aminobuteric acid (GABA)-gated chloride channels on nerve cell membranes. Granular formulations are broadcast on turfgrass areas and control ants about 4 to 8 weeks after application. Control continues for up to a year.

(Topchoice® Insecticide, Taurus®G Insecticide Granules, both RESTRICTED USE products for purchase and use only by licensed pesticide personnel)

Inorganic compounds - Boric acid is a slow-acting stomach poison. It is commonly formulated as a dust or liquid bait for control of ants. Diatomaceous earth (DE) acts as a desiccant by scratching and absorbing the waxy layer that makes up part of the insect's exoskeleton. DE is most commonly applied as a dust to ant foraging trails to kill foraging ants; however, this use will have little or no effect on the ant colony or nest. Insecticide grade DE products are available, but when applied as a dry dust to the top of an ant mound or as a drench, fail to contact ants. Also, high humidity in ant mounds prevents desiccation. Thus, this ingredient acts more as a carrier in fire ant products that list DE as an active ingredient. When DE is used as a carrier in formulations of pyrethrins, it may enhance the penetration of this botanical insecticide into the body of an insect.

For more information and specific products and costs, visit the Products section at Fire Ant Project and Fire Ant Control Materials for Alabama Homeowners.