Etoxazole
[CAS# 153233-91-1]

Identification

• Classification: Chemical pesticide >> Insecticide >> Acaricide
• Name: Etoxazole
• Synonyms: 2-(2,6-Difluorophenyl)-4-[4-(tert-butyl)-2-ethoxyphenyl]-4,5-dihydrooxazole
• Molecular Formula: C₂₁H₂₃F₂NO₂
• Molecular Weight: 359.41
• CAS Registry Number: 153233-91-1
• EC Number: 604-891-2
• SMILES: CCOC1=C(C=CC(=C1)C(C)(C)C)C2COC(=N2)C3=C(C=CC=C3F)F

Properties

• Melting point: 218-221 ºC (Expl.)
• Flash point: 457 ºC (Expl.)

Safety Data

• Hazard Symbols: GHS09 Warning
• Hazard Statements: H400:-H410:
• Precautionary Statements: P273-P391-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400

Discovory and Applicatios

Etoxazole is an acaricide and insecticide belonging to the oxazoline class of chemicals, developed primarily for use in agricultural pest control. The discovery of etoxazole was driven by the need for novel agents capable of controlling populations of mites and certain insect pests that had developed resistance to conventional acaricides. It was first synthesized and evaluated in the 1990s, during a period marked by active development of compounds with new modes of action to address resistance issues in integrated pest management (IPM) programs.

Etoxazole exhibits its biological activity by inhibiting the molting process of mites and insects. It acts specifically on chitin synthesis, which is essential for the formation of the exoskeleton in arthropods. The compound demonstrates excellent selectivity, primarily affecting juvenile stages of pest mites such as *Tetranychus urticae* (two-spotted spider mite), while being largely non-toxic to adult mites and beneficial insects. This selectivity makes it a useful component of IPM, as it allows the preservation of natural predators that contribute to biological control in crops.

Chemically, etoxazole is characterized by a substituted oxazoline ring system, which is essential to its biological function. Its structure and molecular properties confer both high potency against target pests and good residual activity on treated plants. In practice, it is typically applied as a foliar spray and shows strong adhesion and rainfastness, which are desirable properties for field applications. Etoxazole is effective on a wide variety of crops, including fruits, vegetables, and ornamental plants.

One of the major advantages of etoxazole is its minimal mammalian toxicity and low environmental impact when used according to guidelines. It degrades relatively rapidly in the environment, reducing the risk of long-term accumulation in soil and water. Moreover, its low toxicity to birds and fish further supports its ecological compatibility. However, as with all pesticides, improper or excessive use can lead to resistance development. As a result, rotation with other acaricides that have different modes of action is recommended to maintain its long-term efficacy.

Etoxazole has gained regulatory approvals in numerous countries and is incorporated into crop protection regimes worldwide. Its use is particularly prevalent in controlling mite infestations in high-value crops such as apples, citrus, grapes, and strawberries, where mite outbreaks can cause substantial economic losses. The compound's unique properties, including its ovicidal and larvicidal activity, make it an ideal choice for early intervention strategies in pest management.

In summary, etoxazole represents a significant advancement in agricultural chemistry, providing an effective tool for mite control with minimal non-target impact. Its development addressed a critical need for selective, environmentally conscious pest control options, and its continued use exemplifies the importance of targeted chemical innovation in sustainable agriculture.

References

2023. Quantitative assessment of selective degradation behavior of etoxazole in different classes of organisms by compound-specific isotope analysis. Ecotoxicology and Environmental Safety, 252.
DOI: 10.1016/j.ecoenv.2023.114632

2023. Using targeted sequencing and TaqMan approaches to detect acaricide (bifenthrin, bifenazate, and etoxazole) resistance associated SNPs in Tetranychus urticae collected from peppermint fields and hop yards. PLOS ONE, 18(3).
DOI: 10.1371/journal.pone.0283211

2002. Genetic Basis of Resistances to Chlorfenapyr and Etoxazole in the Two-Spotted Spider Mite (Acari: Tetranychidae). Journal of Economic Entomology, 95(6).
DOI: 10.1603/0022-0493-95.6.1267