Insecticidal, food utilisation and biochemical effect of essential oils extracted from seeds of Brassica juncea (Czern.) against Spodoptera litura (Lepidoptera: Noctuidae) (Fabricius)

Abstract

The glucosinolate rich hot and cold hexane extracts of Brassica juncea had a negative effect on the development of Spodoptera litura larvae when they were fed on different concentrations of the extracts. Both larval growth index and pupal growth index declined with treatment. However the hot extract with 3-butenyl isothiocyanate as the predominant compound had a more deleterious effect as at 3125ppm the larvae were unable to complete their development. The nutritional indices too were more adversely affected with hot extract as compared to cold extract. The RGR, RCR, ECI and ECD declined significantly with increase in concentration of the hot hexane extract. The activity of antioxidant enzymes, SOD and catalase decreased while that of phosphatases, GSTs, phenol oxidases increased during the initial treatment duration but decreased on prolonged treatment of the larvae with LC50 concentration of hot extract. A similar trend was observed for glutathione and lipid peroxides but a decrease in ascorbate content was observed as compared to control. The findings reveal a toxic effect of 3-butenylisothiocyanate rich hot hexane extract of B. juncea on S. litura larvae