Bio-Pesticidal Potential of Nanostructured Lipid Carriers Loaded with Thyme and Rosemary Essential Oils against Common Ornamental Flower Pests

Abstract

The encapsulation of essential oils (EOs) in nanostructured lipid carriers (NLCs) represents a modern and sustainable approach within the agrochemical industry. This research evaluated the colloidal properties and insecticidal activity of NLCs loaded with thyme essential oil (TEO-NLC) and rosemary essential oil (REO-NLC) against three common arthropod pests of ornamental flowers: Frankliniella occidentalis, Myzus persicae, and Tetranychus urticae. Gas chromatography–mass spectrometry (GC-MS) analysis identified the major chemical constituents of the EOs, with TEO exhibiting a thymol chemotype and REO exhibiting an α-pinene chemotype. NLCs were prepared using various homogenization techniques, with high shear homogenization (HSH) providing the optimal particle size, size distribution, and surface electrical charge. A factorial design was employed to evaluate the effects of EO concentration, surfactant concentration, and liquid lipid/solid lipid ratio on the physicochemical properties of the nanosuspensions. The final TEO-NLC formulation had a particle size of 347.8 nm, a polydispersity index of 0.182, a zeta potential of −33.8 mV, an encapsulation efficiency of 71.9%, and a loading capacity of 1.18%. The REO-NLC formulation had a particle size of 288.1 nm, a polydispersity index of 0.188, a zeta potential of −34 mV, an encapsulation efficiency of 80.6%, and a loading capacity of 1.40%. Evaluation of contact toxicity on leaf disks showed that TEO-NLC exhibited moderate insecticidal activity against the western flower thrips and mild acaricidal activity against the two-spotted spider mite, while REO-NLC demonstrated limited effects. These findings indicate that TEO-NLCs show potential as biopesticides for controlling specific pests of ornamental flowers, and further optimization of the administration dosage could significantly enhance their effectiveness.