The Insecticide Resistance Action Committee (IRAC) was formed in 1984 and works as a specialist technical group of the industry association CropLife to be able to provide a coordinated industry response to prevent or delay the development of insecticide resistance in insect, mite and nematode pests. IRAC strives to facilitate communication and education on insecticide and traits resistance as well as to promote the development and facilitate the implementation of insecticide resistance management strategies. [1]
IRAC is recognised by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) of the United Nations as an advisory body on matters pertaining to insecticide resistance. [2]
Pesticideresistance.org is a database financed by IRAC, US Department of Agriculture, and others. [3]
IRAC's sponsors are: ADAMA, BASF, Bayer CropScience, Corteva, FMC, Mitsui Chemicals, Nihon Nohyaku, Sumitomo Chemical, Syngenta and UPL. [4]
IRAC publishes an insecticide mode of action (MoA) classification that lists most common insecticides and acaricides and recommends that "successive generations of a pest should not be treated with compounds from the same MoA Group". [5] [6] IRAC assigns a mode of action (MoA) to an insecticide, based on sufficient scientific data. [7] They then update the mode of action (MoA) classification. [5] Several insecticides and classes of insecticide may act through the same mode of action. [8]
If an insecticide is successful, follow-on insecticides, based on the chemical structure of the first in class (prototype) insecticide, may be developed either by the original company or by competitors. Sought after are insecticides which have improved properties or which kill different orders or species of insect. The resulting classes of insecticides are named by IRAC after common usage has been established, although alternative names may be found in the scientific literature.
In the table the number of insecticides listed in each class is given, and an example of each class. The number of insecticides in the IRAC class listing as of 2024 [update] is given in column Nr (A). The number in the Compendium of Pesticide Common Names [9] (insecticide + acaricide) is given in column Nr (B), although the name given there to the class historically is often different to the IRAC class name.
| IRAC code | Mode of action | Class | Nr (A) | Nr (B) | Example |
|---|---|---|---|---|---|
| 1 A | Acetylcholinesterase (AChE) inhibitors | Carbamates | 26 | 52 | Carbofuran |
| 1 B | Acetylcholinesterase (AChE) inhibitors | Organophosphates | 66 | 171 | Chlorpyrifos |
| 2 A | GABA-gated chloride channel blockers | Cyclodiene organochlorines | 2 | 17 | Endosulfan |
| 2 B | GABA-gated chloride channel blockers | Phenylpyrazoles (Fiproles) | 2 | 7 | Fipronil |
| 3 A | Sodium channel modulators | Pyrethroids, Pyrethrins | 43 | 84 | Permethrin |
| 3 B | Sodium channel modulators | DDT, Methoxychlor | 2 | 20 | DDT |
| 4 A | Nicotinic acetylcholine receptor (nAChR) competitive modulators | Neonicotinoids | 7 | 11 | Imidacloprid |
| 4 B | Nicotinic acetylcholine receptor (nAChR) competitive modulators | Nicotine | 1 | 1 | Nicotine |
| 4 C | Nicotinic acetylcholine receptor (nAChR) competitive modulators | Sulfoximines | 1 | 1 | Sulfoxaflor |
| 4 D | Nicotinic acetylcholine receptor (nAChR) competitive modulators | Butenolides | 1 | 1 | Flupyradifurone |
| 4 E | Nicotinic acetylcholine receptor (nAChR) competitive modulators | Mesoionics | 3 | 3 | Triflumezopyrim |
| 4 F | Nicotinic acetylcholine receptor (nAChR) competitive modulators | Pyridylidenes | 1 | 1 | Flupyrimin |
| 5 | Nicotinic acetylcholine receptor (nAChR) allosteric modulators - Site I | Spinosyns | 2 | 2 | Spinosad |
| 6 | Glutamate-gated chloride channel (GluCl) allosteric modulators | Avermectins, Milbemycins | 4 | 10 | Abamectin |
| 7 A | Juvenile hormone receptor modulators | Juvenile hormone analogues | 3 | 7 | Methoprene |
| 7 B | Juvenile hormone receptor modulators | Fenoxycarb | 1 | 1 | Fenoxycarb |
| 7 C | Juvenile hormone receptor modulators | Pyriproxyfen | 1 | 1 | Pyriproxyfen |
| 8 A | Miscellaneous non-specific (multi-site) inhibitors | Alkyl halides | > 3 | 10 | 1,3-dichloropropene |
| 8 B | Miscellaneous non-specific (multi-site) inhibitors | Chloropicrin | 1 | 1 | Chloropicrin |
| 8 C | Miscellaneous non-specific (multi-site) inhibitors | Fluorides | 2 | 5 | Sulfuryl fluoride |
| 8 D | Miscellaneous non-specific (multi-site) inhibitors | Borates | 5 | 2 | Boric acid |
| 8 E | Miscellaneous non-specific (multi-site) inhibitors | Tartar emetic | 1 | 0 | Tartar emetic |
| 8 F | Miscellaneous non-specific (multi-site) inhibitors | Methyl isothiocyanate generators | 3 | 2 | Dazomet |
| 9 B | Chordotonal Organ TRPV Channel Modulators | pyridine azomethine derivatives | 2 | 2 | Pymetrozine |
| 9 D | Chordotonal Organ TRPV Channel Modulators | Pyropenes | 1 | 1 | Afidopyropen |
| 10 A | Mite growth inhibitors affecting CHS1 | Clofentezine, Diflovidazin, Hexythiazox | 3 | 5 | Clofentezine |
| 10 B | Mite growth inhibitors affecting CHS1 | Etoxazole | 1 | 1 | Etoxazole |
| 11 A | Microbial disruptors of insect midgut membranes | Bacillus thuringiensis and the insecticidal proteins they produce | 4 | n.a. | n.a. |
| 11 B | Microbial disruptors of insect midgut membranes | Bacillus sphaericus | 1 | n.a. | n.a. |
| 12 A | Inhibitors of mitochondrial ATP synthase | Diafenthiuron | 1 | 1 | Diafenthiuron |
| 12 B | Inhibitors of mitochondrial ATP synthase | Organotin miticides | 3 | 8 | Cyhexatin |
| 12 C | Inhibitors of mitochondrial ATP synthase | Propargite | 1 | 4 | Propargite |
| 12 D | Inhibitors of mitochondrial ATP synthase | Tetradifon | 1 | 2 | Tetradifon |
| 13 | Uncouplers of oxidative phosphorylation via disruption of the proton gradient | Pyrroles, Dinitrophenols, Sulfluramid | 3 | 8 | Chlorfenapyr |
| 14 | Nicotinic acetylcholine receptor (nAChR) channel blockers | Nereistoxin analogues | 4 | 5 | Thiocyclam |
| 15 | Inhibitors of chitin biosynthesis affecting CHS1 | Benzoylureas | 11 | 15 | Lufenuron |
| 16 | Inhibitors of chitin biosynthesis, type 1 | Buprofezin | 1 | 1 | Buprofezin |
| 17 | Moulting disruptor, Dipteran | Cyromazine | 1 | 1 | Cyromazine |
| 18 | Ecdysone receptor agonists | Diacylhydrazines | 4 | 6 | Tebufenozide |
| 19 | Octopamine receptor agonists | Amitraz | 1 | 7 | Amitraz |
| 20 A | Mitochondrial complex III electron transport inhibitors – Qo site | Hydramethylnon | 1 | 1 | Hydramethylnon |
| 20 B | Mitochondrial complex III electron transport inhibitors – Qo site | Acequinocyl | 1 | 1 | Acequinocyl |
| 20 C | Mitochondrial complex III electron transport inhibitors – Qo site | Fluacrypyrim | 1 | 4 | Fluacrypyrim |
| 20 D | Mitochondrial complex III electron transport inhibitors – Qo site | Bifenazate | 1 | 1 | Bifenazate |
| 21 A | Mitochondrial complex I electron transport inhibitors | METI acaricides and insecticides | 6 | 9 | Tebufenpyrad |
| 21 B | Mitochondrial complex I electron transport inhibitors | Rotenone | 1 | 1 | Rotenone |
| 22 A | Voltage-dependent sodium channel blockers | Oxadiazines | 1 | 1 | Indoxacarb |
| 22 B | Voltage-dependent sodium channel blockers | Semicarbazones | 1 | 1 | Metaflumizone |
| 23 | Inhibitors of acetyl-CoA carboxylase | Tetronic and Tetramic acid derivatives | 5 | 6 | Spirotetramat |
| 24 A | Mitochondrial complex IV electron transport inhibitors | Phosphides | 4 | 3 | Phosphine |
| 24 B | Mitochondrial complex IV electron transport inhibitors | Cyanides | 3 | 3 | Sodium cyanide |
| 25 A | Mitochondrial complex II electron transport inhibitors | Beta-ketonitrile derivatives | 2 | 6 | Cyenopyrafen |
| 25 B | Mitochondrial complex II electron transport inhibitors | Carboxanilides | 1 | 1 | Pyflubumide |
| 28 | Ryanodine receptor modulators | Diamides | 5 | 19 | Chlorantraniliprole |
| 29 | Chordotonal organ nicotinamidase inhibitors | Flonicamid | 1 | 2 | Flonicamid |
| 30 | GABA-gated chloride channel allosteric modulators | Meta-diamides, Isoxazolines | 3 | 15 | Broflanilide |
| 31 | Baculoviruses | Granuloviruses (GVs), Nucleopolyhedroviruses (NPVs) | 4 | n.a. | Cydia pomonella GV |
| 32 | Nicotinic Acetylcholine Receptor (nAChR) Allosteric Modulators - Site II | GS-omega/kappa HXTX-Hv1a peptide | 1 | n.a. | GS-omega/kappa HXTX-Hv1a peptide |
| 33 | Calcium‐activated potassium channel (KCa2) modulators | Acynonapyr | 1 | 1 | Acynonapyr |
| 34 | Mitochondrial complex III electron transport inhibitors – Qi site | Flometoquin | 1 | 1 | Flometoquin |
| 35 | RNA Interference mediated target suppressors | Ledprona | 1 | 2 | Ledprona |
| 36 | Chordotonal organ modulators – undefined target site | Pyridazine pyrazolecarboxamides | 1 | 1 | Dimpropyridaz |
| 37 | Vesicular acetylcholine transporter (VAChT) inhibitor | Oxazosulfyl | 1 | 1 | Oxazosulfyl |
| UN | Compounds of unknown or uncertain MoA | many various classes | 10 | 83 | Benzoximate |
| UNB | Bacterial agents (non-Bt) of unknown or uncertain MoA | class not defined | 2 | n.a. | Wolbachie pipientis (Zap) |
| UNE | Botanical essence including synthetic, extracts and unrefined oils with unknown or uncertain MoA | class not defined | 5 | n.a. | neem oil |
| UNF | Fungal agents of unknown or uncertain MoA | class not defined | 6 | n.a. | Beauveria bassiana strains |
| UNM | Non-specific mechanical and physical disruptors | class not defined | 3 | n.a. | Mineral Oil |
| UNP | Peptides of unknown or uncertain MoA | no examples | none | n.a. | no examples |
| UNV | Viral agents (non-baculovirus) of unknown or uncertain MoA | no examples | none | n.a. | no examples |