Mesoporous silica nanoparticles enhance the toxicity of chlorantraniliprole to <i>Spodoptera frugiperda</i> by possibly inhibiting energy metabolism and chitin protein synthesis

Nanosized formulations are an important means to develop effective pesticide molecules against target pests with improved environmental safety. In this study, we constructed a nanodelivery system using mesoporous silica nanoparticles (MSNs) carrying chlorantraniliprole (CLAP). The drug loading rate was determined using liquid chromatography, and CLAP@MSNs were characterized and analyzed. Adhesion was measured by contact angle and surface tension, and UV resistance was assessed. The transport of CLAP@MSNs within plants was observed using confocal fluorescence microscopy. Additionally, larval bioassay experiments and RNA-seq analyses were conducted on CLAP@MSNs. The results indicate that CLAP (35.6% w/w) has been successfully loaded onto MSNs. CLAP@MSNs appeared to have structure and size similar to MSNs. CLAP@MSNs showed effective adhesion to the surface of corn leaves and stems and also resisted to UV photolysis. Bidirectional delivery of fluorescently labeled CLAP@MSNs through vascular bundles in corn. When administered to Spodoptera frugiperda, mortality in CLAP@MSNs-treated larvae increased whereas weight and developmental period decreased significantly compared with larvae treated with CLAP alone. RNA-seq analysis revealed that oral administration of CLAP@MSNs led to the downregulation of genes associated with drug metabolism, energy metabolism, and chitin protein synthesis, thereby inhibiting the growth and development of insects. Interestingly, CLAP@MSNs exerted no harmful effects on growth of plants and development of non-target organisms. Taken together, CLAP@MSNs provide a safe, effective, and economical insecticidal nanopesticide system that potentially further improves the effectiveness of CLAP against lepidopteran pests, contributing to the reduction of pesticide use in pest management.