Exploring Ternary Essential Oil Mixtures of Moroccan Artemisia Species for Larvicidal Effectiveness Against Culex pipiens Mosquitoes: A Mixture Design Approach.

Essential oils (EOs) have gained significant attention for their biopesticidal properties in pest management. This study investigates the insecticidal potential of EOs extracted from the aerial parts of three indigenous Artemisia species-Artemisia absinthium, Artemisia arborescens, and Artemisia campestris-collected from various provenances in Morocco. The EOs were tested individually and in combination against Culex pipiens (C. pipiens) larvae to explore potential synergistic interactions using a mixture design methodology. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography with flame ionization detection (GC-FID) analyses revealed quantitative and qualitative variations in the chemical composition of the oils. The primary constituents of A. absinthium were identified as thujone (32.20% ± 2.65%), camphor (19.95% ± 2.64%), and chamazulene (19.58% ± 2.33%). In A. arborescens, thujone (52.05% ± 3.84%), camphor (10.71% ± 3.08%), and eucalyptol (4.79% ± 1.53%) were the major components, while A. campestris comprised camphor (18.98% ± 2.65%), car-3-en-5-one (11.25% ± 2.33%), and thujone (6.63% ± 1.67%). When applied individually, all three EOs exhibited significant larvicidal activity against C. pipiens larvae, with A. arborescens showing the highest efficacy (LC₅₀ 11.11 μg/mL (5.45 ± 22.62)) compared to A. absinthium (LC₅₀: 16.98 μg/mL (6.73 ± 27.39)) and A. campestris (LC₅₀: 19.07 μg/mL (13.57 ± 23.38)). In mixture experiments, the mixture design outcomes reveal that the ternary formulation comprising 58% A. absinthium, 26% A. arborescens, and 16% A. campestris emerged as the most effective blend, achieving complete larval eradication. This study highlights the potential of Artemisia EO combinations as a sustainable and effective alternative for managing mosquito vectors of disease.