Effects of Tabernaemontana elegans and Lantana camara-derived nanoparticles on the hatching and mortality of Meloidogyne incognita second-stage juveniles under in vitro conditions

Abstract

This study investigated the synthesis of green nanoparticles (NPs) from <i>Lantana camara</i> (NPlc) and <i>Tabernaemontana elegans</i> (NPte) using <i>Aloe vera</i> as a reducing and stabilizing agent. It further assessed the impact of the synthesized nanoparticles on <i>Meloidogyne incognita</i> juvenile hatch and mortality. Nanoparticles were synthesized by combining plant extracts and <i>A. vera</i> gel in five volume ratios (100:0, 25:75, 50:50, 75:25, and 0:100 v/v). The physical characteristics of the nanoparticles were analyzed using UV-Vis spectroscopy, transmission electron microscopy (TEM), and selected area electron diffraction (SAED). The results confirmed the polycrystalline structure and morphological diversity (cubic, triangular, platelet, and irregular forms) of the nanoparticles, with composition ratios significantly influencing their structural properties. All concentrations with Aloe gel produced nano-scale (<21 nm) products, whereas the single extracts were larger than the accepted nano-scale size. The optimal combination of <i>A. vera</i> extract ratio was found to be 50:50, accompanied by small nanoparticles exhibiting a highly defined ring pattern and well-developed polycrystalline structures. In bioassays, different concentrations of NPlc and NPte significantly (P ≤ 0.05) inhibited <i>M. incognita</i> juvenile hatch and increased juvenile mortality. The lowest juvenile hatch rates (6.9-7%) and highest inhibition levels (72-74%) were recorded at the 50:50 plant extract to <i>A. vera</i> ratio. Hatch inhibition and mortality were time-dependent, with minimal effects observed at 24 hours and the highest (79%) responses at 72 hours of exposure. These findings demonstrate that green-synthesized nanoparticles can be produced from <i>L. camara</i> and <i>T. elegans</i>, which possess strong nematicidal potential and may serve as sustainable, eco-friendly alternatives to conventional chemical nematicides.