Browsing by Author "Ojumoola, A.O"
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Item Effects of Seasonal Variation on Chemical Constituents and Insecticidal Activity of Leaf Essential Oil of Citrus limonium(Nigerian Society of Biochemistry and Molecular Biology, 2015) Usman, L.A; Olanipekun, B.E; Ismaeel, R.O.; Oguntoye, S.O.; Ojumoola, A.OLeaves (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.Item Susceptibility of the life stages Callosobruchus maculatus (Fabr.) in stored cowpea grains to fumigation with essential oil vapour of Ocimumbasilicum L. leaves.(Faculty of Food and Agriculture, University of the West Indies, Trinidad and Tobago., 2016) Ojumoola, A.O; Adesiyun, A.A.; Usman, L.AThis study was carried out to investigate the susceptibility of the life stages of Callosobruchus maculatus (F.) in stored cowpea to the essential oil vapour of sweet basil, Ocimum basilicum, L.leaves when applied as a fumigant. The extracted and analysed essential oil of O. basilicum leaves in this study was made up mainly of monoterpenoids and sesquiterpenoids with ϒ-terpinene (12.2%), and β-caryophyllene (10.4%) predominating. In separate bioassays, cowpea seeds harbouring the different life stages of C. maculatus were exposed to the oil vapour within a hermetic structure. The essential oil vapour had insecticidal effects on the adults of C. maculatus. Mortality was observed to significantly (P<0.05) increase from 14.8% to 100% as dosage increased from 10μl/80ml air to 60μl/80ml air. Significantly high percentage mortality (98.48%) of C. maculatus eggs was observed after three days of seed fumigation with the essential oil vapour. The percentage mortality caused by the oil vapour to the larval and pupal stages within fumigated cowpea seeds was not significantly different from the control at P=0.05 after three days of fumigation. It was thus concluded that the egg and adult stages of C. maculatus were more susceptible to the essential oil vapour of O. basilicum leaves than the larvae and pupae stages within stored cowpea.