Insecticidal efficacy of zinc oxide and silicon dioxide nanoparticles against larvae of <i>Spodoptera frugiperda</i> J. E. Smith (Lepidoptera: Noctuidae)

The objective of this research was to evaluate the insecticidal efficacy of zinc oxide (ZnO-NPs) and silicon dioxide (SiO2-NPs) nanoparticles on fall armywormSpodoptera frugiperda second instar larvae under laboratory. The components of these nanoparticles can interfere with the developmental physiology of the insect and, at high concentrations, cause its mortality. Insecticide susceptibility tests were performed on the larvae in artificial diet-based poisoning conditions with six concentrations (400, 600, 800, 1000, 2000 and 3000 ppm), along with a control (0 ppm) and 25 individual replicates for each concentration. ZnO-NPs have a hemispherical shape, with a size of 60.82 nanometers (nm), whereas SiO2-NPs have a spherical shape and size of 45.73 nm. Bioassays showed that at 3000 ppm concentration of both nanoparticles produced 100% mortality. At seven days, the mean Lethal Concentration (LC50) of SiO2-NPs was 727.3 ppm . In the case of ZnO-NPs, the LC50 reported at 343.4 ppm , in the same period. The NPs caused visible damage such as a reduction in larvae body length, alterations in their morphology, especially in the dorsal and ventral regions. Pink and dark spots, generalized malformations, body necrosis, and mummified bodies (death). The ZnO-NPs and SiO2-NPs nanoparticles present an efficient and innovative solution for the control of S. frugiperda.