DNA-tagged nano gold: A new tool for the control of the armyworm, Spodoptera litura Fab. (Lepidoptera: Noctuidae)

The efficacy of the DNA tagged gold nanoparticles on the major polyphagous pest, Spodoptera litura Fab. (Lepidoptera: Noctuidae) was evaluated. To determine the efficacy of the test nanoparticle, dilutions viz. 200, 300, 400 and 500 ppm were prepared and 10 µl of the suspension was dispensed on the chickpea (Cicer aritinum) based semi-synthetic diet filled in 5 ml glass vials. Second instar S. litura larvae of uniform age and size were released onto the diet 20 min after surface treatment. 20 larvae of S. litura were exposed to each concentration of DNA tagged gold nanoparticle for 30 s. A control with untreated larvae was also maintained. Larval mortality data sets subjected to analysis of variance (ANOVA) revealed that the particles were effective and caused 50% larval mortality above 500 ppm. As the particle concentration and days after treatment increased, larval mortality also increased. There were statistically significant differences in Spodoptera larval mortality between concentrations. The LC50 (216.91 to 938.95 conc. at 95% CI) increased as the larval age increased. The study demonstrated that DNA tagged gold nanoparticles are effective against S. litura and would therefore be a useful component of an integrated pest management strategy.