Synthesis of silica nanoparticles from rice husk to determine insecticidal properties against Glyphodes pyloalis walker (Lepidoptera: Crambidae)

The technology of producing silica nanoparticles from agricultural waste is the most economical method because of cheapness and abundance of agricultural waste at the end of harvest. Silica nanoparticles induce plant resistance, act as an insecticide by blocking insect spiracles, causing cuticle disruption and increasing the concentration of free radicals. Silica nanoparticles were synthesized from rice husk (SNRH) and their insecticidal properties were evaluated against the larvae of Glyphodes pyloalis Walker through the leaf-dipping method. This evaluation was followed by a qualitative examination using a scanning electron microscope and XRD analysis. The results showed an LC30 of 0. 0.115% for SNRH against fourth instar larvae. Treatment of mulberry leaves with the LC30 concentration influenced biological parameters and statistically decreased nutritional indices including ECD (Efficiency of conversion of digested food), ECI (Efficiency of conversion of ingested food), RCR (Relative consumption rate) and RGR (Relative growth rate). The activity of lipase, trypsin, chymotrypsin, elastase and aminopeptidase decreased in the larvae fed on SNRH-treated leaves. The larvae that consumed SNRH-treated leaves showed higher activity of catalase, peroxidases and superoxide dismutase while other antioxidant enzymes showed no statistical difference compared to control. Our results demonstrated that SNRH had insecticidal properties against G. pyloalis by disrupting the nutritional and antioxidant traits of the larvae.