Effects of Ag/SiO2 Nanoparticles on Gene Expression of Digestive a-Amylase in Colorado Potato Beetle

Abstract

Insecticidal properties of nanoparticles (NPs) have been considered widely in different studies. In this study, synthesis of Ag/SiO2 NPs is reported and the effect of the nanoparticles on the digestive a-amylase gene expression in the Colorado potato beetle (CPB), Lepidoptera decemlineata say is investigated. For this purpose, the inhibition of fourth instar larval digestive a-amylase with NPs was analyzed by different concentrations, and the highest inhibitory effect was recorded (72%) at 1000 ppm of Ag/SiO2 NPs. Mortality for the reared larvae from the first instar on potato leaves coated with 1000 ppm Ag/SiO2 NPs was 65%, while it is 8% for the control trial. To investigate the process, we conjugated the nanoparticles with extracted RNA, and the photoluminescent (PL) spectra of the obtained materials were measured and investigated. The results indicate that the FRET phenomenon occurs when the RNA reacts with nanoparticles. These results are according to the PL spectra of RNAs extracted from the larval fed with nanoparticles. The structure is simulated and calculated by the DFT method. The obtained results confirm chemical interaction between nanoparticles and nitrogenous bases on the RNA which can decrease gene expression (0.47 fold) compared to control and causes inhibition of larvae’s growth.