Toxicity evaluation of sulfur nanoparticles (SNPs) on the date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae) under laboratory and field conditions

Phytophagous mites are among the most common pests, causing economic losses to the world’s crops. A promising area for managing diseases and pests and increasing agricultural productivity is nanotechnology. Sulfur in the form of nanoparticles was synthesized using an extract of fenugreek as a capping agent to provide a smaller size of the particles and enhance the stability of its suspension. The microscopic and spectroscopic analyses elucidated the physical and chemical nature of the obtained particles. The synthesized particles were spherical and had an average diameter of 43.8 nm with Zeta potential values of -34.8 mV. The purpose of this research was to assess the efficacy of sulfur nanoparticles (SNPs) against all stages of the date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae). This includes its effects on the predatory mite, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), on date palm trees under laboratory and field conditions. Five concentrations of sulfur nanoparticles (500, 1000, 1500, 2000, and 2500 ppm) were tested. SNPs caused concentrationdependent mortality in O. afrasiaticus, reaching 89.33% in the lab and 84.83% in the field at 2500 ppm, while impacts on A. swirskii remained at a minimal 18.33%. The egg hatchability of O. afrasiaticus also declined significantly across treatments. Overall, sulfur nanoparticles effectively reduced date palm mite populations with negligible harm to predatory mite, indicating their potential as a selective and environmentally friendly control option.