Satureja calamintha essential oil: Chemical composition and assessing insecticidal efficacy through activity against acetylcholinesterase, chitin, juvenile hormone, and molting hormone.

Abstract

Plant-derived insecticides based on essential oils (EOs) are currently considered as an excellent option to reduce the adverse effects associated with synthetic pesticides. In this study, we attempted to analyse the chemical composition, insecticidal properties and inhibition of biological parameters, as well as to evaluate the mode of action of the bioactive components of Satureja calamintha essential oil in relation to molecular targets in three life stages of the insect Callosobruchus maculatus. Gas chromatography-mass spectrometry (GC-MS) was used to investigate the phytochemical profile of the essential oil. Inhalation and contact tests with the insect Callosobruchus maculatus (C. maculatus) were carried out to evaluate the insecticidal activity, and in silico molecular docking techniques were used to evaluate the mode of action. Extraction of the essential oil gave a yield of 1.72% and chromatographic analysis revealed the presence of 19 potentially active compounds, of which pulegone (52.4%) and neo-dihydrocarveol (16.1%) were the main ones. Toxicity tests by contact and inhalation showed that the tested EOs exhibited significant insecticidal activity against C. maculatus after 24 h exposure, achieving 100% mortality in the inhalation test and 87% in the contact test. With a lethal dose (LC50) of 4.43 and 9.34 μL/L air, respectively, at 24 h exposure. In addition, exposure to EO showed inhibition of oviposition and emergence at all insect life stages tested, and this inhibition increased with increasing dose, reaching complete inhibition at a concentration of 20μL/L.