Bioefficacy and GC-MS analysis of Chromolaena odorata and Leonotis nepetifolia leaf extracts against Spodoptera litura

This study aimed to assess the insecticidal properties from leaf extracts of Chromolaena odorata L. and Leonotis nepetifolia (L) R.Br. on the third instar larvae of tobacco leaf-eating Spodoptera litura (F.). Leaves of both plant species were extracted with three solvents, acetone, methanol, and water, then tested for ovicidal, antifeedant, and larvicidal activity at 0.5, 1, 2.5, 5, and 7%. The methanol extract (5%) of C. odorata was found more active for ovicidal (73.33 ± 0.57%), antifeedant (82.45 ± 0.16%), and larvicidal (68.33 ± 0.05%) activities against S. litura. Similar results were noted from methanol extract (5%) of L. nepetifolia for ovicidal (71.33 ± 0.41%), antifeedant (71.77 ± 0.73%), and larvicidal (73.33 ± 0.08) activities. Phytochemical screening revealed a significant amount of alkaloids and phenolics in methanolic leaf extracts of both plants. Besides, thirty-one bioactive compounds from the methanolic extract of C. odorata and sixteen compounds from L. nepetifolia were identified by GC-MS analysis. The recorded compounds are phenols, fatty acids, esters, and essential oils with insecticidal properties. The insecticidal compounds detected from GC-MS and quantitative phytochemical analysis might be attributed to the high insecticidal potential (Ovicidal, antifeedant and larvicidal) of C. odorata and L. nepetifolia. Therefore extensive research on C. odorata and L. nepetifolia is needed in phytopesticide development against Spodoptera litura.