CROP PROTECTION, cilt.196, 2025 (SCI-Expanded, Scopus)
This study investigated the acaricidal and repellent properties of Trachystemon orientalis (L.) G. Don (Boraginaceae) extracts against Tetranychus urticae Koch (Acari: Tetranychidae), a significant agricultural pest. Extracts were obtained from plant material subjected to shade and oven drying, using distilled water, methanol, and 75 % methanol containing 0.1 % formic acid. The aqueous extract prepared from oven-dried material (ES) exhibited the highest mortality, causing 92.93 % mortality at 10 % concentration after 24 h. In contrast, the methanol-formic acid extract from shade-dried material (GF) showed the strongest repellent activity (86.67 %) at 1 % concentration, with the effect persisting over 24 h. Biochemical profiling through LC-MS/MS identified major phenolic constituents, including rosmarinic acid, caffeic acid, o- and p-salicylic acid, p-coumaric acid, and protocatechuic acid. Rosmarinic acid was the most abundant phenolic compound, particularly in the GF. The extract also exhibited the strongest antioxidant activity (2073.42 mg GAE/100 g dry matter (dm)) in total phenolic content (TPC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. A positive correlation was observed between the salicylic acid content of the ES extract and its acaricidal activity. High levels of rosmarinic acid, caffeic acid, p-salicylic acid, and chrysophanol were detected in shade-dried methanol (GM) and oven-dried methanol (EM) extracts, which had the highest repellency. Drying methods and solvents significantly influenced biological activity: water extracts were more acaricidal on T. urticae, while methanol extracts were more repellent. These findings suggest that T. orientalis could serve as a natural alternative to synthetic acaricides, offering a safer option for integrated pest management in sustainable agriculture. Future research should explore field applications, interactions with biopesticides, and effects on other pest populations and ecosystems.