Usman, L.AOlanipekun, B.EIsmaeel, R.O.Oguntoye, S.O.Ojumoola, A.O2021-09-142021-09-142015Usman, L. A., Olanipekun, B. E., Ismaeel, R. O., Oguntoye, S. O. &Ojumoola, A. O.(2015): Effects of Seasonal Variation on Chemical Constituents and Insecticidal Activity of Leaf Essential Oil of Citrus limonium. Nigerian Journal of Biochemistry and Molecular Biology, 30 (2): 126-133https://uilspace.unilorin.edu.ng/handle/20.500.12484/6308Leaves (500g) of Citrus limonium harvested in the morning (7.00 am) during dry and rainy seasons were separately hydrodistilled and yielded 0.46 and 0.30 % (w/w) of essential oils. GC and GC-MS analysis revealed that the oils obtained from dry and rainy season harvests were predominated by monoterpenoids (84.2% and 77.2%). The most abundant constituent of the oils from dry and rainy season harvests was; limonene (17.9% and 15.3%). Other principal constituents of the oils were; β-pinene (8.0% and 1.5%), terpinolene (7.0% and 7.1%), citronellal (12.9% and 8.3%), carveol (8.0% and 9.0%), neral (7.9% and 8.5%). citronellol (4.4% and 5.9%) and β-caryophyllene (3.3% and 5.2%). Contact toxicity bioassay was used to investigate the insecticidal activity of the oils against Callosobruchus maculatus. Irrespective of the season of harvest the oils were active against the insect. Interestingly, oils from the two harvests had comparable activity against the adult C. maculatus. Hence, seasonal variation has no significant effect on insecticidal activity of the oil on the postharvest insect pest.enPost-harvestLimonene synthaseCallosobruchus maculatusCitrus limoniumArticle