Acrinathrin

Acrinathrin is a synthetic pyrethroid insecticide and acaricide used to control agricultural pests, especially phytophagous mites and some sucking or scraping insects.

Common name: acrinathrin

Number CAS: 101007-06-1

Gross chemical formula: C26H21F6NO5

Chemical class: Synthetic pyrethroid (derived from hexafluoro-2-propanol). It belongs to the IRAC 3A group (sodium channel modulators). It is classified as a Type II pyrethroid due to the presence of the cyano α group.

Main names of commercial products in Brazil: Rufast 50 SC

Development history: Developed by Roussel Uclaf (RU code 38702) in France. Commercially introduced in 1990. It is a pyrethroid produced as a highly active single isomer through complex multi-step chemical synthesis, optimized to maximize insecticidal and acaricidal activity and minimize impurities. Currently, the main commercial product with the molecule belongs to FMC due to a succession of mergers and acquisitions: (a) Roussel Uclaf's agrochemical assets were transferred to Hoechst Schering AgrEvo in 1994; (b) Hoechst merged its agricultural division (AgrEvo) with the agrochemical division of Rhône-Poulenc, forming Aventis CropScience, in 1999; (c) Bayer AG acquired Aventis CropScience for €7,25 billion in 2002; (d) Cheminosa acquired the acrinathrin business outside of Europe in December 2006; (e) FMC Corporation acquired Cheminosa A/S in 2015.

Mechanism of action: It acts through contact and ingestion. It acts as a neurotoxin modulating voltage-dependent sodium channels in the nervous system of insects and mites. It prolongs the opening of these channels, causing neuronal hyperexcitability, tremors, paralysis, and death. It belongs to group 3A of the IRAC.

Control spectrum: Effective against plant-eating mites and insects such as thrips, psyllids, leaf miners, and aphids. Resistance has been reported in some populations of Tetranychus urticae and Frankliniella occidentalis. In Brazil, Rufast 50 SC is primarily positioned as an acaricide.

Compatibilities and interactions: As a pyrethroid, it generally exhibits good physical compatibility with many foliar fungicides and fertilizers, but it is always recommended to perform a jar test (physical compatibility) and observe phytotoxicity in sensitive crops. Studies in citrus farming evaluate mixtures of acaricides with foliar fertilizers to optimize applications. Avoid mixtures with strongly alkaline products (which can degrade pyrethroids) or those that potentiate toxicity. High toxicity to bees and aquatic organisms requires care in mixtures and application windows. Cross-resistance with other pyrethroids (group 3A) may occur.

Agronomic positioning: Foliar application (ground spraying) with good coverage, as the action is predominantly by contact. In Brazil, Rufast 50 SC is indicated, according to the product label, for the control of specific pests (mites and some insects) in vegetables and other registered crops.

In Integrated Pest Management (IPM) programs, it should be rotated with insecticides and acaricides from other chemical groups to delay resistance. Due to its toxicity to bees, avoid applications during flowering or apply at night. Low water solubility, low volatility, and strong adsorption to the soil (low leaching). Moderate persistence in the soil (DT₅₀ ≈ 20–40 days under field conditions). Monitor residues to ensure compliance with Maximum Residue Limits (MRLs), which are low in several markets (e.g., EU).