Usman, L.A2021-09-142021-09-142016Usman, L.A., Watti. O.I., Ismaeel, R.O. &Ojumoola, A.O.(2016): Effect of drying on yield, chemical composition, and insecticidal activity of leaf essential oil of sweet orange (Citrus sinensis). Journal of the Turkish Chemical Society A, 3(1):1-18https://uilspace.unilorin.edu.ng/handle/20.500.12484/6315Pulverized fresh and dried leaves of citrus sinensis (500g) that were dried for five consecutive days during dry season were separately hydro-distilled for 3 hours. Oil yields from samples ranged from 0.1 - 0.37% (w/w). Characterization of the oils using Gas Chromatography-Mass Spectrometry showed that the oil was predominated by monoterpenoids (5.7 - 90.2%). Car-3-ene was the most abundant compound in the oils from fresh and the leaves dried for four days. The insecticidal activity of oils against Callosobruchus maculatus was also determined via contact toxicity bioassay. Regardless of the level of dryness, the oils were observed to be toxic to C. maculatus. Oils obtained from the leaves dried for five days were found to be more active against the insect than other oils.enDryingEssential oilcitrus sinensisterpene synthasecallosobrushus maculatusArticle