Diamide insecticides are a class of insecticides, active mainly against lepidoptera (caterpillars), which act on the insect ryanodine receptor. They are diamides of either phthalic acid or anthranilic acid, with various appropriate further substitutions. [1] [2]
Worldwide sales of diamides in 2018 were estimated at US$ 2.4 billion, which is 13% of the $18.4 billion insecticide market. [3]
The first diamide was flubendiamide. It was invented by Nihon Nohyaku and commercialised in 2007. [1] It is a highly substituted diamide of phthalic acid and is highly active against lepidoptera (caterpillers). [1] [2] Later DuPont introduced chlorantraniliprole, which is more active against caterpillers and in addition active against other insect types. [1] [2] Cyanthraniliprole, introduced later, shows systemic activity and is also active against sucking pests such as aphids and whitefly. [2]
According to one review, the first species reported to show resistance to diamides was the diamondback moth in 2012. [4]
The following diamides have been given ISO common names. [5] Flubendiamide and cyhalodiamide are phthalic [6] diamides. [5] Chlorantraniliprole, cyantraniliprole, cyclaniliprole, fluchlordiniliprole, pioxaniliprole, tetrachlorantraniliprole, tetraniliprole, and tiorantraniliprole are anthranilic [7] diamides. [5] Eight diamide insecticides have been commercialized as of February 2023. [2]
Diamides selectively activate insect ryanodine receptors (RyR), which are large tetrameric ryanodine-sensitive calcium release channels present in the sarcoplasmic reticulum and endoplasmic reticulum in neuromuscular tissues. [8] The diamides form IRAC group 28. [9] The ryanodine receptor is also the target of the alkaloid insecticide ryanodine, after which it is named, although it addresses a different binding site on the receptor. [8] A 3.2-Å structure of cyanthraniliprole bound to a ryanodine receptor has been determined, which informs on the mechanism of action as well as various mutations causing resistance. [2]
The binding of diamides and ryanodine to the calcium channels causes them to remain open, leading to the loss of calcium crucial for biological processes. [10] This causes insects to act lethargic, stop feeding, and eventually die. [10]
Diamides show low acute mammalian toxicity. [11] They are safe to bees and beneficial insects. [11]
A metabolite of flubendiamide is very persistent and toxic to aquatic invertebrates, causing flubendiamide to be banned by the United States EPA. [12]
Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, industrial buildings, for vector control, and control of insect parasites of animals and humans.
Ryanodine receptors form a class of intracellular calcium channels in various forms of excitable animal tissue like muscles and neurons. There are three major isoforms of the ryanodine receptor, which are found in different tissues and participate in different signaling pathways involving calcium release from intracellular organelles. The RYR2 ryanodine receptor isoform is the major cellular mediator of calcium-induced calcium release (CICR) in animal cells.
Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole insecticide class. Fipronil disrupts the insect central nervous system by blocking the ligand-gated ion channel of the GABAA receptor and glutamate-gated chloride (GluCl) channels. This causes hyperexcitation of contaminated insects' nerves and muscles. Fipronil's specificity towards insects is believed to be due to its greater binding affinity for the GABAA receptors of insects than to those of mammals, and for its action on GluCl channels, which do not exist in mammals. As of 2017, there does not appear to be significant resistance among fleas to fipronil.
The avermectins are a group of 16-membered macrocyclic lactone derivatives with potent anthelmintic and insecticidal properties. These naturally occurring compounds are generated as fermentation products by Streptomyces avermitilis, a soil actinomycete. Eight different avermectins were isolated in four pairs of homologue compounds, with a major (a-component) and minor (b-component) component usually in ratios of 80:20 to 90:10. Avermectin B1, a mixture of B1a and B1b, is the drug and pesticide abamectin. Other anthelmintics derived from the avermectins include ivermectin, selamectin, doramectin, eprinomectin.
Ryanodine is a poisonous diterpenoid found in the South American plant Ryania speciosa (Salicaceae). It was originally used as an insecticide.
Benzoylureas (BPUs) are chemical derivatives of N-benzoyl-N′-phenylurea, which are used as insecticides. They do not directly kill the insect, but disrupt moulting and egg hatch, and thus act as insect growth regulators. They act by inhibiting chitin synthase, preventing the formation of chitin in the insect's body.
Spinosad is an insecticide based on chemical compounds found in the bacterial species Saccharopolyspora spinosa. The genus Saccharopolyspora was discovered in 1985 in isolates from crushed sugarcane. The bacteria produce yellowish-pink aerial hyphae, with bead-like chains of spores enclosed in a characteristic hairy sheath. This genus is defined as aerobic, Gram-positive, nonacid-fast actinomycetes with fragmenting substrate mycelium. S. spinosa was isolated from soil collected inside a nonoperational sugar mill rum still in the Virgin Islands. Spinosad is a mixture of chemical compounds in the spinosyn family that has a generalized structure consisting of a unique tetracyclic ring system attached to an amino sugar (D-forosamine) and a neutral sugar (tri-Ο-methyl-L-rhamnose). Spinosad is relatively nonpolar and not easily dissolved in water.
Indoxacarb is an oxadiazine pesticide developed by DuPont that acts against lepidopteran larvae. It is marketed under the names Indoxacarb Technical Insecticide, Steward Insecticide and Avaunt Insecticide. It is also used as the active ingredient in the Syngenta line of commercial pesticides: Advion and Arilon.
The milbemycins are a group of macrolides chemically related to the avermectins and were first isolated in 1972 from Streptomyces hygroscopicus. They are used in veterinary medicine as antiparasitic agents against worms, ticks and fleas. They also show insecticidal and acaricidal activity.
Tuta absoluta or Phthorimaea absoluta is a species of moth in family Gelechiidae known by the common names South American tomato pinworm, tomato leafminer, tomato pinworm and South American tomato moth. It is well known as a serious pest of tomato crops in Europe, Africa, western Asia and South and Central America, with larvae causing up to 100% loss if not effectively controlled.
CropLife International is an international trade association of agrochemical companies founded in 2001. It was previously known as Global Crop Protection Federation and started out as International Group of National Associations of Manufacturers of Agrochemical Products in 1967. Its members include the world's largest agricultural biotechnology and agricultural pesticide businesses namely BASF, Bayer CropScience, Corteva, FMC Corp., Sumitomo Chemical and Syngenta. The international body combines several national-level or continent-wide organisations, each one having the same goals but differing according to local language and custom.
An insect growth regulator (IGR) is a chemical insecticide that kills insects indirectly by disrupting their life cycles. The term was initially proposed to describe the effects of juvenile hormone analogs. Although the term "insect growth disruptor" more accurately describes the actions of IGRs, it did not become widely used. IGRs encompass chemical classes with three modes of action : juvenile hormone analogs, chitin synthesis inhibitors, and ecdysone receptor agonists.
Tefluthrin is the ISO common name for an organic compound that is used as a pesticide. It is a pyrethroid, a class of synthetic insecticides that mimic the structure and properties of the naturally occurring insecticide pyrethrin which is present in the flowers of Chrysanthemum cinerariifolium. Pyrethroids such as tefluthrin are often preferred as active ingredients in agricultural insecticides because they are more cost-effective and longer acting than natural pyrethrins. It is effective against soil pests because it can move as a vapour without irreversibly binding to soil particles: in this respect it differs from most other pyrethroids.
Cyantraniliprole is an insecticide of the diamide class. It shows strong activity and lepidoptera (caterpillars), and since it shows systemic activity it is also active against sucking pests such as aphids and whitefly.
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 and mite 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.
Flubendiamide is the first insecticide of the diamide class. It acts on the ryanodine receptor.
Etoxazole is a narrow spectrum systemic acaricide used to combat spider mites. It targets a variety of mites in the egg, larvae and nymph stages however not the adult stage. It also exhibits insecticidal activity towards aphids, the green rice leafhopper and diamondback moth. The mode of action has been shown to inhibit chitin synthase (IRAC group 10B). Resistance due to its high efficacy and cross resistance when used with other acaricides are both of concern similar to was seen in the fast development of cross resistance in the previous generation of acaricides. The LC50 for resistant mite strains has been observed over 100,000 times greater than that of susceptible strains. Thus resistance management strategies are important in order to limit the increase of etoxazole resistant mite strains.
Chlorantraniliprole is an insecticide of the diamide class used for insects found on fruit and vegetable crops as well as ornamental plants.
Flupyradifurone is a systemic butenolide insecticide developed by Bayer CropScience under the name Sivanto. Flupyradifurone protects crops from sap-feeding pests such as aphids and is safer for non-target organisms compared to other insecticides. Sivanto was launched in 2014 since it obtained its first commercial registration in central America. Insecticide Resistance Action Committee (IRAC) classified Flupyradifurone as 4D subset (butenolide) and it is the first pesticide in the butenolide category. It was approved by European Union in 2015.
Pymetrozine is an insecticide in the pyridine-azomethine chemical class, primarily utilized for controlling homopteran pests, such as aphids and whiteflies, in agricultural settings. Its mode of action selectively targets the feeding behavior of sap-feeding insects, causing them to cease feeding soon after ingestion. This unique mechanism limits its impact on non-target organisms, including beneficial insects. Pymetrozine has been extensively used on rice, potatoes, a wide variety of vegetable brassica crops and various other crops as an alternative to organophosphorus pesticides.
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