Diamide insecticides

Flubendiamide, a phthalic diamide insecticide
Chlorantraniliprole, an anthranilic diamide insecticide
Cyantraniliprole, another anthranilic diamide insecticide

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]

History and examples

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]

Mechanism of action

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]

Toxicity

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]

References

  1. ^ a b c d Jeanguenat, Andre (28 August 2012). "The story of a new insecticidal chemistry class: the diamides". Pest Management Science. 69 (1): 7−14. doi:10.1002/ps.3406. PMID 23034936.
  2. ^ a b c d e f Du, Shaoqing; Hu, Xueping (February 15, 2023). "Comprehensive Overview of Diamide Derivatives Acting as Ryanodine Receptor Activators". Journal of Agricultural and Food Chemistry. 71 (8): 3620–3638. doi:10.1021/acs.jafc.2c08414. PMID 36791236.{{cite journal}}: CS1 maint: date and year (link)
  3. ^ Sparks, Thomas C (2024). "Insecticide mixtures—uses, benefits and considerations". Pest Management Science. doi:10.1002/ps.7980. PMID 38356314 – via Wiley.
  4. ^ Richardson, Ewan B.; Troczka, Bartlomiej J.; Gutbrod, Oliver; Davies, T. G. Emyr; Nauen, Ralf (2020-06-01). "Diamide resistance: 10 years of lessons from lepidopteran pests". Journal of Pest Science. 93 (3): 911–928. doi:10.1007/s10340-020-01220-y. ISSN 1612-4766.
  5. ^ a b c "Compendium of Pesticide Common Names. Insecticides". British Crop Production Council (BCPC). Retrieved 12 November 2024.
  6. ^ This can be determined by examination of the chemical structure
  7. ^ This can be determined by examination of the chemical structure
  8. ^ a b Nauen, Ralf; Steinbach, Denise (27 August 2016). "Resistance to Diamide Insecticides in Lepidopteran Pests". In Horowitz, A. Rami; Ishaaya, Isaac (eds.). Advances in Insect Control and Resistance Management. Cham: Springer (published 26 August 2016). pp. 219–240. doi:10.1007/978-3-319-31800-4_12. ISBN 978-3-319-31800-4.{{cite book}}: CS1 maint: date and year (link)
  9. ^ Sparks, Thomas C; Storer, Nicholas; Porter, Alan; Slater, Russell; Nauen, Ralf (2021). "Insecticide resistance management and industry: the origins and evolution of the I nsecticide R esistance A ction C ommittee (IRAC) and the mode of action classification scheme". Pest Management Science. 77 (6): 2609–2619. doi:10.1002/ps.6254. ISSN 1526-498X. PMC 8248193. PMID 33421293.
  10. ^ a b Teixeira, Luís A; Andaloro, John T (2013). "Diamide insecticides: Global efforts to address insect resistance stewardship challenges". Pesticide Biochemistry and Physiology. 106 (3): 76–78. doi:10.1016/j.pestbp.2013.01.010.
  11. ^ a b Jeschke, Peter; Witschel, Matthias; Krämer, Wolfgang; Schirmer, Ulrich (25 January 2019). "Chapter 36, Insecticides Affecting Calcium Homeostasis". Modern Crop Protection Compounds, Volume 3: Insecticides (3rd ed.). Wiley-VCH. pp. 1541–1583. doi:10.1002/9783527699261.ch36. ISBN 9783527699261.{{cite book}}: CS1 maint: date and year (link)
  12. ^ "Flubendiamide – Notice of Intent to Cancel and Other Supporting Documents". United States Environmental Protection Agency. February 14, 2024. Retrieved 12 November 2023.