Potencial biotecnológico de óleos essenciais para o controle de Meloidogyne javanica

Abstract

Root-knot nematodes of the genus Meloidogyne are plant-parasitic organisms that affect a wide range of economically important crops, such as tomato, soybean, and cotton. These nematodes induce the formation of galls on the roots, impairing nutrient and water absorption, which results in reduced plant growth and productivity. Due to the environmental impact and health risks associated with the use of chemical nematicides, there is increasing interest in alternative strategies, such as the use of plant- derived products, including extracts and essential oils. These oils are complex mixtures of bioactive compounds, such as esters, ketones, and alcohols, known for their biological activity and potential in controlling phytopathogens. Although most nematicidal studies have focused on direct-contact applications, the assessment of the volatile action of these compounds is crucial to explore additional control mechanisms based on vapor release. In this study, the volatile activity of essential oils was evaluated against Meloidogyne javanica at the egg and second-stage juvenile (J2) stages. The essential oil of Ruta chalepensis was extracted by steam distillation and characterized by gas chromatography coupled with mass spectrometry (GC-MS). Essential oils from Citrus × limonia, Pelargonium graveolens, and Siparuna guianensis were also evaluated. Tested concentrations ranged from 0.1 to 8 μL mL⁻¹ of air, using dimethyl sulfoxide (DMSO) and water as negative controls, and a commercial bionematicide, Vigga® SC, as a positive control. GC-MS analysis identified 2-undecanone (51.94%), 2-nonanone (22.36%), and 2-acetoxytridecane (7.72%) as the major components of the R. chalepensis essential oil. In the volatile activity assessment, R. chalepensis induced 95.4% mortality in J2 at a concentration of 7.16 μL mL⁻¹ of air (CL₉₀), while Citrus × limonia reached 100% at 8 μL mL⁻¹ of air. P. graveolens caused 65% of mortality and S. guianensis 16% at the same concentration. Regarding egg hatch inhibition, only the essential oil of R. chalepensis was evaluated, showing mortality rates of 81.7% at the concentration of 1 μL mL⁻¹ of air and 95.5% at 4 μL mL⁻¹ of air. These findings highlight the nematicidal potential of volatile compounds present in essential oils, especially that of R. chalepensis, whose effectiveness was demonstrated through the exposure of nematodes to its vapors. The volatile activity evaluation technique proved to be a promising tool for the biological control of M. javanica, offering a sustainable and effective alternative to conventional nematicides in the management of these plant pathogens.