Lignin-enabled silica hybrid nanoparticles from rice husk for improved biopesticide delivery and cotton bollworm control

This study investigates the production of lignin/silica hybrid nanoparticles (LSNPs) from rice husk, an abundant agricultural byproduct, for the delivery of soybean trypsin inhibitor (STI), a bioinsecticide. Lignin was extracted from rice husk under alkaline conditions and co-precipitated with silica to form LSNPs. Characterization revealed that lignin imparted hydrophobicity to the nanoparticles and increased their surface area, enhancing their potential for pesticide delivery. The hybrid nanoparticles were evaluated for their ability to resist washout, control STI release, and provide effective biocontrol against cotton bollworm larvae - one of the most damaging pests in cotton crops. The results indicates that lignin played a critical role in imparting hydrophobicity to the nanoparticles, significantly enhancing their adhesion to hydrophobic plants such as cotton. The hybrid nano-formulations exhibited superior foliar adherence, washout resistance, and pH-responsive release (28.1 % at pH 9). STI delivered with LSNP achieved 99.1 % insect weight reduction, and complete (100 %) mortality rate compared to 75.8 % weight reduction and 66.7 % mortality rate when delivered by pure silica. This work highlights the synergistic potential of combining lignin and silica from the same bio-based source in enhancing both foliar adhesion and bioactivity of biopesticides, offering a promising alternative for sustainable pest management in agriculture.