The potential biopesticidal effects of torrefaction liquid of corn stalk pellets against Tetranychus urticae Koch, 1836 (Acari: Tetranychidae)

While torrefaction improves the fuel properties of biomass pellets, the chemical components of secondary products in liquid form are highly valuable in the industrial field. In addition, the components of the liquid have the potential to be used as biopesticides. In this study, corn stalk pellets were torrefied at 320 °C and torliquid was obtained as a secondary product from condensable gases during the process. Calorific value of the corn stalk pellets increased from 19.10 MJ kg−1 to 22.58 MJ kg−1 during torrefaction process. According to the Gas Chromatography-Mass Spectrometry findings, the torliquid contained mostly acidic components (52.20 %) due to the nearly complete degradation of hemicellulose. Potential bioactivity of the torliquid on the two-spotted spider mite Tetranychus urticae Koch, 1836 (Acari: Tetranychidae), worldwide major phytophagous pest, was investigated. Dipping method and half-treated leaf disc assay were used to determine lethal and repellent effects, respectively. The concentration series of 12.5, 25 and 50 % for the determination of bioactivity were prepared by torliquid using distilled water. The highest concentration caused 84 % and 100 % mortalities for eggs and adult stages, respectively. The repellant effects of the torliquid varied depending on concentrations and duration of exposure. The egg rates in the immersed half part of the cowpea discs at the increasing concentrations were found to be 15.5, 2.1 and 0.0 %, respectively, after 48 h. Research findings have revealed that corn torliquid may be a suitable biopesticide to be used in T. urticae management, as it has a significant effect, cost-effective and plant biomass origin. © 2024 Elsevier Ltd