Nematicidal and insecticidal activity of essential oils from Artemisia scoparia and Centratherum punctatum and their mixtures

The present study involves the phytochemical analysis and assessing potential synergies among essential oils (EOs) against pests. The EOs were obtained by hydrodistillation from the aerial part (ASAO) and the root part (ASRO) of Artimisia scoparia, and from the aerial part of Centratherum punctatum (CPAO). The EOs yield ranged from 0.5 to 0.1% (v/w). The GC-MS analysis revealed the presence of 35, 43, and 49 compounds, constituting 99.2%, 98.34%, and 99.93% in ASAO, ASRO, and CPAO, respectively. Capillene was identified as the dominant compound both in ASAO and ASRO, but in variable amounts. Caryophyllene oxide (36.4%) was identified as the major component of CPAO. Pure EOs were blended in binary and ternary mixtures at ratios to analyze their synergistic effect against pests. The nematicidal activity (percent mortality and egg hatchability against Meloidogyne incognita at different concentrations was evaluated and the ternary mixture (ASAO + ASRO + CPAO) was found to be most effective at 1 μL/mL with 55.67 ± 1.41% larval immobility at 96 h of exposure. The antifeedant activity of pure and blended EOs was examined against Spodoptera litura using the leaf-dip method. Individually ASAO was most effective with 66.91% feeding inhibition, however the ternary combination showed 58.03% feeding inhibition. Moreover, molecular docking of selected volatiles (≥4% area) from the tested samples was carried out to analyze the interactions with target protein; acetylcholinesterase (AChE) and glutathione S-transferases (GST-1) and the ligands interacted favourably with the target proteins. The blending of EOs resulted in synergistic effects, enhancing their efficacy. Data acquired highlighted that A. scoparia and C. punctatum essential oils could be natural alternatives for nematode control and pest control in agriculture.