The objective of this study was the fabrication of encapsulated Satureja hortensis essential oil (S.EO) in chitosan/tripolyphosphate nanoparticles (CS/TPP-NPs) via ionic gelation technique and investigation of its acaricidal effect. A high encapsulation efficiency of 96.17% was obtained, which shows successful encapsulation of EOs in CS-TPP nanoparticles. Transmission electron microscopy (TEM) analysis proved the formation of spherical S. hortensis EO-loaded chitosan nanoparticles (S.EO@NPs). Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated the presence of encapsulated S.EO in CS/TPP nanoparticles. The average size of nanoparticles was found to be 192.1 ± 11 nm using dynamic light scattering (DLS) technique. Moreover, durability and fumigant acaricide activity of S.EO@NPs against Tetranychus urticae Koch were investigated. The obtained results demonstrated that there were considerable differences between pure S. hortensis EO and S.EO@NPs in their ovicidal, adulticidal, and persistence activities against T. urticae. The LC50 values of pure EO and as-prepared S.EO@NPs against adult mite were 4.95, 46.98 µL/L after 24 h exposure and 2.02, 31.30 µL/L after 72 h exposure, respectively. Fumigation exposure for 24 and 72 h showed that the sensitivity of adults T. urticae were more than the eggs of T. urticae. The LC50 values of fumigant toxicity of pure S.EO and S.EO@NPs against eggs of T. urticae were measured after 24 and 72 h. The experimental results for 24 h treatment showed 6.71 and 211.66 µL/L air LC50 values for pure S.EO and S.EO@NPs, respectively. In the case of 72 h exposure, The LC50 values of pure S.EO and S.EO@NPs were 4.15 and 107.38 µL/L air, respectively. A sustained release of S.EO from S.EO@NPs was observed during 25 days of the study, indicating the persistence acaricide activity for a long time. The as-prepared S.EO@NPs and pure S.EO illustrated 67% and 2% mortality at 18th day exposure, respectively. The notable increasing of the r
