Composition and biocidal properties of essential oil from pre-domesticated Spanish Satureja Montana

The aim of this study was to develop a chemically stable plant following a pre-domestication process and the valorization of its essential oil for the production of biopesticides. This study was conducted during four growing seasons to give a pre-domesticated population (SAMO-0). The resulting pre-domesticated population increased the hydrodistilled oil yield (average 0.45%) and maintained a stable yield of dry material (44.5%). The plant material was submitted to pilot plant scale steam distillation under three pressures (0.5, 1.0 and 1.5 bar) with lower yield (average 0.15%). The essential oil showed a carvacrol / p-cymene chemotype. The pre-domestication process increased β-myrcene, α- and γ-terpinene, p-cymene, thymol and β-bisabolene; and decreased α-thujene and carvacrol. The steam distillation increased the oil content in α-thujene, α-pinene, α-terpinene, p-cymene and trans-caryophyllene, and decreased borneol, thymoquinone thymol and β-bisabolene. Pressure increased α-terpinene, thymol and carvacrol Additionally, the study of the biocidal effects (against the insect pests Spodoptera littoralis, Myzus persicae and Leptinotarsa decemlineata and the phytopathogenic nematode Meloydogine javanica) of the EOs showed that overall, the most active oils were the hydrodistilled (to all insect species), followed by the steam distilled oils with higher carvacrol and thymol content (pressures of 1.5 and 1.0 bar). Carvacrol and thymol were responsible for the activity of these oils on M. persicae, and L. decemlineata but only partially on S. littoralis. The steam distilled oils showed strong nematicidal activity against M. javanica that could be partially explained by their content in active carvacrol and thymol.