Biochemical effect of silica nanoparticles on fall armyworm Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) and maize plants Zea mays Linneaus, 1753

The fall armyworm Spodoptera frugiperda (J. E. Smith) attacks maize (Zea mays Linneaus, 1753) plants in all their stages, and causing severe damage. This study was aimed to evaluate the toxicological, biochemical, and biological effects of hydrophilic silica nanoparticles (HSNps) on S. frugiperda with 4 concentrations (500, 1000, 2000, and 3000 ppm). Also, the biochemical effects of LC50 on maize plants under semi field conditions were evaluated. Results showed that LC50 values were 127.88, 136.96 and 875.18 ppm for the 1st, 2nd and 3rd larval instar after 7 days of treatment, respectively. HSNps prolonged duration of the larval and pupal stages and pre-oviposition period. On opposite, HSNps decreased both of pupal weight, adult longevity, number of eggs/female, incubation period and hatchability %. Moreover, HSNps have a negative effect on larval digestive and defensive enzymes such as proteases, lipase, amylase, B-glucosidases, and carboxylesterase enzymes. But, HSNps increased chitinase, phenoloxidase enzymes and total amount of proteins. Foliar spraying of HSNps stimulate activity of antioxidant enzymes and increases the amount of total proteins, carbohydrates, and nitrogen (N). But inhibit total phenols, flavonoids, terpenoids, and potassium (K) and phosphorus (P) of maize plants. These results provide evidence that HSNps have the potential for use as a safe alternative to control the fall armyworm.