Volatile Oil Composition, Phytochemical Screening and Insecticidal Activities of Indigofera tinctoria Against African Pink Worm Borer

Abstract The following study presents the constituents of the volatile oils found in the leaves and seeds of Indigofera tinctoria, as well as the secondary metabolites of its leaves crude fractions. The insecticidal activities of these fractions against Sesamia calamistis were also evaluated. The volatile oils from the leaf and seed of Indigofera tinctoria were extracted using the hydro-distillation method, utilizing an all-glass Clevenger apparatus. The extracted oils were then characterized using the Gas Chromatography-Mass Spectrometry (GC-MS) technique. The n-hexane, ethyl acetate and ethanol fractions of I. tinctoria were also investigated for secondary metabolites using standard qualitative phytochemical analysis methods. The insecticidal activities of these fractions against Sesamia calamistis were evaluated using a contact toxicity test procedure. The results of the study showed that Phytol (34.1%) and 1-octen-3-ol (63.8%) were the major constituents of the leaf and seed oil of I. tinctoria, respectively. Saponins were present in the hexane and ethanol fractions, while terpenoids and tannins were present in the ethyl acetate and ethanol fractions. The ethyl acetate fraction showed the highest percentage of S. calamistis larvae mortality of 70.0% at a 0.4% concentration compared to the n-hexane and ethanol fractions. Therefore, the ethyl acetate fraction of I. tinctoria leaf at a 0.4% concentration with the highest percentage of larvae mortality could be used to manage Sesamia calamistis on maize.