Growth Perturbation, Abnormalities and Mortality of Oriental Armyworm Mythimna separata (Walker) (Lepidoptera: Noctuidae) Caused by Silica Nanoparticles and Bacillus thuringiensis Toxin

Impact of silica (Sio2) nanoparticles against 3rd larval instar of the oriental armyworm, Mythimna separate (Walker) (Lepidoptera: Noctuidae) was tested under the laboratory conditions. As well, was the effect of the soil application with such material on resistance of wheat plants to this pest, when compared with Bacillus thuringiensis (Bt), the effective bioagent against lepidopteran pests. Nutrition proportion, longevity, growth and morality rates of treated and untreated larvae were measured. Data indicated that both treatments significantly affected the life table of this pest, but the Bt had the superiority. Feeding inhibition rate reached 37.16 and 43.91% in soil and foliar treatments with silica, respectively, while it was 70.74% in the Bt treatment. Relative growth rate approximately was decreased twice compared to the control. Larval stage period elongated from 26.30 days in control to 30.89, 30.67, 34.83 and 33.00 days in silica soil, silica foliar, Bt-foliar and Bt-Silica foliar treatments, respectively. Divergences occurred in mortality percentages of larvae between 10.00% in control, 84.63 in larvae treated with Bt and 67.69% when sprayed with silica. Furthermore, significant increase occurred in wheat plant features when silicon dioxide fertilization system was applied. In conclusion, the present results suggest the possible use of silica (Sio2) nanoparticles to control the oriental armyworm, M. separate.