Tea waste-derived wood vinegar as a bio-based acaricide: Toxicity, repellency and control of Polyphagotarsonemus latus (banks) on bean plants

Abstract

Polyphagotarsonemus latus (Banks) (Acari: Tarsonemidae) is a major pest of numerous crops worldwide. Tea wood vinegar, derived from pyrolysed tea residues, is a sustainable pest management option. This study evaluated the ovicidal, adulticidal, and repellent activities of tea wood vinegar against P. latus under laboratory conditions and assessed its effect on mite populations on infested bean plants. Its chemical composition was analysed using GC-MS, and major volatile and phenolic compounds were identified. Ten vinegar concentrations (1%-20% v/v) were tested. Bioassays were conducted using a leaf-disc method with distilled water and calcium polysulphide as controls. Potted plant assays were also conducted to evaluate population suppression under controlled conditions. Egg mortality reached up to 94.95%, although higher concentrations caused phytotoxic effects. At non-phytotoxic concentrations (5-7.5%) in leaf discs, ovicidal activity remained high (49.5-69.7%), while calcium polysulphide showed low efficacy (3.95% mortality). Adult mortality reached 88-97% at 2.5-5% after 24 h, and repellency ranged from 96 to 100% at 5-7.5% after 96 h. LC50 values were 5.20% for eggs and 1.51% for adults, indicating effective control at non-phytotoxic levels. In potted plants, concentrations of 1-2.5% effectively reduced mite populations below the economic threshold without visible phytotoxicity, whereas higher concentrations resulted in complete suppression but caused leaf injury. Overall, tea wood vinegar showed measurable acaricidal, ovicidal, and repellent activity against P. latus under controlled conditions, with effects dependent on concentration.