Phytochemical and acaricidal study of the Kermani lemongrass, Dracocephalum polychaetum Bornm. (Lamiaceae) essential oil against Tetranychus urticae Koch

ABSTRACT Mites cause significant damage to various crops, often requiring synthetic acaricides for their control. However, the frequent use of these products, resistance problems and severe problems with contamination occur. Therefore, one of the promising solutions is plant acaricides, which can be developed based on essential oils. Thus, the objective of this work was the extraction and characterization of the essential oil from the leaves of Kermani lemongrass, Dracocephalum polychaetum, and acaricidal evaluation of the oil and its major compound using the application by fumigation on female adults of Tetranychus urticae. The composition of the essential oil was analysed by GC-MS. The major components in the oil were 1-octen-3-ol (11.27%), 6-methyl-5-hepten-2-one (11.06%), linalool (9.89), and nonanal (9.64%), respectively. The impact of essential oil of this plant on fumigant toxicity, LT50, oviposition deterrent activity, and repellency against T. urticae was studied at different concentrations. The results stated that D. polychaetum oil had high toxicity on eggs and adults of two-spotted spider mite (LC50 was 60.30 and 50.87 µL L−1 for eggs and adults, respectively) with LT50 of 8.02 h. In addition, all tested concentrations had oviposition deterrent activity and repellency in adults of this mite.