Aphicidal activity of urea-formaldehyde nanocapsules loaded with the Thymus daenensis Celak essential oil on Brevicoryne brassicae L.

Nowadays, the applications of nanotechnology in pesticide formulation have rapidly increased to improve the efficacy and safety of biopesticides. In the present study, the essential oil (EO) of aerial parts of Thymus daenensis Celak was isolated through hydro-distillation. The composition of T. daenensis EO was then identified using gas chromatography and mass spectrophotometry (GC-MS). Nanocapsule containing T. daenensis EO prepared via in situ polymerization technique using oil/water-based emulsion method. Transmission electron microscopy (TEM) was performed to determine morphology and surface of the nanocapsules. The mean diameter and poly-dispersity index (PDI) of nanocapsules were determined through dynamic light scattering technique. Finally, contact and fumigant toxicities of raw and encapsulated T. daenensis EOs were evaluated against cabbage aphid (Brevicoryne brassicae L.). GC-MS technique revealed that major chemical compounds of T. daenensis EO were thymol (56.61%) and carvacrol (17.02%). TEM images showed that nanocapsules loaded with T. daenensis EO have clear core-shell structures with spherical shapes. The range of diameter of nanoparticles was between 8.30 to 17.61 nm with the median diameter (x(50)) of 12.10 nm and a PDI of 0.098. Based on the relative toxicity ratios, contact LC50 and LC90 of nanocapsulated formulation (208.28 and 1026.44 ppm) were significantly smaller than raw EO (702.57 and 2367.62 ppm). Similarly, fumigant LC50 and LC90 of nanocapsulated formulation (10.55 and 32.31 mu l/l air) were significantly smaller compared with raw EO (18.66 and 45.65 mu l/l air). The findings were discussed regarding pest management, pesticide efficacy, and wildlife and environmental safety.

Automated summary

The study demonstrated that incorporating Thymus daenensis essential oil into nanocapsules significantly enhanced its toxicity against cabbage aphids, with the nanocapsules showing clear core-shell structures and a smaller diameter range of 8.30 to 17.61 nm. The nanocapsulated formulation exhibited lower LC50 and LC90 values for both contact and fumigant toxicities compared to the raw essential oil, indicating increased pesticide efficacy and improved environmental safety.