Abstract Due to the environmental and health problems caused by synthetic pesticides, there is a need for pesticides derived from natural components. In this study, thymol nanocapsules were prepared using the emulsion-solvent evaporation technique with polylactic acid and polyvinyl alcohol. The particle size distribution and polydispersity index (PDI) of the nanocapsules were determined using dynamic light scattering (DLS) techniques, while their zeta potential was determined using electrophoretic light scattering technique. The particle size of the obtained nanocapsules was determined to be 459 nm, the polydispersity index (PDI) 0.650 ± 0.04, and the zeta potential of -21.31 ± 1.2 mV. Encapsulation efficiency was calculated as 18.03% and the loading capacity as 8.32%. Their morphology was examined using scanning electron microscopy (SEM), and their structural characterization was performed using Fourier-transform infrared spectroscopy (FT-IR). Their thermal properties, encapsulation efficiency (EE) and loading capacity were characterized using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Furthermore, their biological effects were determined using Drosophila melanogaster ( D. melanogaster ) as a model organism. For this purpose, the survival rates, development times, and adult lifespan of D. melanogaster exposed to the nanocapsules were examined. The results show that, particularly at the highest commercial concentration of thymol nanocapsules (100 mg/L), the larval survival rate decreased from 93.00% to 8.00%, and the onset of adult survival decreased from 92.75% to 6.00%. Similarly, at the highest concentration, adult longevity decreased by approximately 20 days compared to the control group, from 25.61 ± 1.03 to 5.79 ± 0.27 days. The results demonstrated that thymol was successfully encapsulated at the nanoscale and induced dose-dependent biological effects in D. melanogaster , characterized by marked reductions in survival rates, delayed development, and shortened adult lifespan. This study is one of the first to reveal the detailed biological effects of thymol on a model organism through PLA-based nanocapsule production, contributing to the production of environmentally friendly biopesticide. Graphical Abstract Schematic representation of thymol-loaded nanocapsules prepared by the emulsion–solvent evaporation method, their core–shell structure, controlled release mechanism, and dosedependent biological effects on Drosophila melanogaster.
Şen et al. (Sun,) studied this question.