Silica nanoparticles control a generalist pest, American serpentine leaf miner Liriomyza trifolii

Insects quickly develop resistance to conventional chemical insecticides. The use of silica nanoparticles (SiO2NPs) is a promising new approach for managing insect pests. The insects that have been studied are, in most cases, external feeders and internal leaf feeders have not been well studied. Here, we investigate the efficiency of SiO2NPs in controlling the American serpentine leafminer Liriomyza trifolii (Diptera: Agromyzidae), a devastating insect pest of a wide range of crops. SiO2NPs at concentrations of 50, 100, 200 and 400 mg/L compared to a control of distilled water were applied to intact Phaseolus vulgaris leaves by spraying on two-week-old intact seedlings to evaluate their effects, via the plant, on the feeding, survival and body mass of L. trifolii released after spraying. A qRT-PCR analysis was conducted to assess oxidative stress in L. trifolii based on the gene expression level of the two major antioxidant enzymes; catalase and superoxide dismutase. The survival rate of larvae was lower than the control at the highest concentration of SiO2NPs, and both larval feeding velocity and pupal weight decreased at the high SiO2NPs concentrations. Gene expression levels of the antioxidant enzymes at the pupal stage were not significantly affected by SiO2NPs at any concentration but some individuals showed up-regulated gene expression level at low SiO2NP concentrations, indicating development of resistance. This study suggests that a high concentration of SiO2NPs should be applied to reduce a leafminer population while avoiding development of resistance.