Scalable synthesis of the major component, geraniol butyrate, of the pheromone of Agriotes sp., an agricultural pest in Ecuador

This study reports the synthesis of geranyl butyrate, a sex pheromone analog of Agriotes spp. click beetles (Coleoptera: Elateridae), whose soil-dwelling larvae — wireworms — cause severe economic losses in cotton, maize, and vegetable crops across Ecuador. The present work targets the development of locally optimized, eco-sustainable protocols to replace costly imported analogs and address the growing resistance of wireworm populations to conventional insecticides (imidacloprid, thiodicarb).

Application doses of 5 and 10 mg were optimized for adult population monitoring and direct control. Two esterification routes were evaluated. Method 1 used butyryl chloride in anhydrous diethyl ether with pyridine, affording the target ester in 60% yield. Method 2 employed butyric anhydride with DMAP catalysis in toluene, accelerating the acylation kinetics and achieving a superior yield of >73%, making it the preferred synthetic protocol.

Molecular characterization by FTIR, GC/MS, and ¹H NMR, combined with physicochemical analysis, confirmed the product as a colorless liquid with characteristic floral odor and 98% purity. Column chromatography (SiO₂; n-hexane/ethyl acetate 95:5) was critical for removing persistent azeotropic impurities. Chemical stability studies revealed hydrolytic sensitivity under non-neutral pH, with direct implications for field formulation design.

From a green chemistry view, targeted synthesis of this structure-specific, low-toxicity ester substantially reduces the environmental impact associated with broad-spectrum pesticide use, promoting a technological sovereignty model in integrated phytosanitary protection. Ongoing research currently explores phase transfer catalysis, heterogeneous catalysts, and microwave-assisted synthesis to further improve yields, atom economy, and process scalability; these results will be reported in forthcoming communications.