Kayode David Ileke

Response of cowpea bruchid,Callosobruchus maculatus(Fab.) (Coleoptera: Chrysomelidae) to cheese wood,Alstonia booneiDe Wild stem bark oil extracted with different solvents

Cheese wood, Alstonia boonei De Wild stem bark was extracted with five different solvents namely: methanol, ethanol, acetone, petroleum ether and n-hexane. The extracts were tested for insecticidal activity on cowpea bruchid, Callosobruchus maculatus (Fab.). Adult mortality and adult emergence of the insects were investigated. Oviposition deterrences using dual-choice and multiple-choice tests were also investigated as well as percentage damage and weight loss at temperature of 28 ± 2 °C and 75 ± 5% relative humidity. Results showed that at the rate of 2% extract per 20 g of cowpea seeds, methanol, petroleum ether and n-hexane extracts caused 100% mortality of adult cowpea bruchid after four days of post treatment. When the bruchid had choice of oviposition substrate, they laid significantly (p < 0.05) fewer eggs on cowpea seeds treated with extracts compared to untreated seeds. There was no adult emergence in seeds treated with methanol, ethanol, petroleum ether and n-hexane extracts and 100% reduction in F1 progeny was recorded compared with untreated that had 81.86% adults emergence and 0% reduction in F1 progeny. The results obtained from this study revealed that methanol, ethanol, acetone, petroleum ether and n-hexane extracts of A. boonei stem bark were effective in controlling C. maculatus and could serve as an alternative to synthetic insecticides for the protection of stored cowpeas against bruchids.

Toxic and essential elements in Nigerian rice and estimation of dietary intake through rice consumption

In this study, levels and estimated daily intake (EDI) of two toxic elements, Cd and Pb, and eight essential elements: Ca, P, Zn, Mn, Co, Cu, Se and Mo, were determined in Nigerian rice samples. The mean levels of Cd, Pb and Co were 5.43 ± 0.88, 38.66 ± 5.42, 25.8 ± 3.18 ng/g. The mean levels of Ca, P, Zn, Mn, Cu, Se and Mo were 71.5 ± 7.31, 951 ± 52.0, 10.2 ± 0.63, 8.5 ± 0.47, 3.07 ± 0.18, 40.1 ± 9.2 and 0.39 ± 0.05 µg/g, respectively. The percentage contribution to the reference values for each element was 0.54, 7.71, 0.38, 9.51, 8.97, 31.3, 30.7, 5.1 and 60.7% for Cd, Pb, Ca, P, Zn, Mn, Cu, Se and Mo, respectively. The elemental nutrient levels in Nigerian rice samples are comparable to those obtained from other regions and their consumption does not pose any serious health risk to consumers.

Efficacy of some plants powder and extract in the management of Angoumois grain moth, Sitotroga cerealella (Olivier) [Lepidoptera: Gelechiidae] infesting stored wheat grains

Powders and extracts prepared from part and products of four plants species indigenous to Nigeria were tested under laboratory condition at 28 ± 2 °C and 75 ± 5% relative humidity for their insecticidal potential against Angoumois grain moth, Sitotroga cerealella. Adult S. cerealella were exposed to three concentrations at rate 0.5, 1 and 2 g of Capsicum frutescens, Cymbopogon citratus, Moringa oleifera and Anacardium occidentale powders and extracts at the rate of 1, 2 and 3%/20 g of wheat grains. Parameters evaluated were adult moth mortality, adult emergence and % hatchability in treated wheat grains after infestation. Results show that significant differences (p < 0.05) existed among the powders and the concentrations. The powder of C. frutescens had the highest mortality rate of 100% after two days of application at all tested concentrations. There were no adult emergence of moth in samples treated with C. frutescens and A. occidentale powders. The extracts completely killed all the adult moths introduced at all tested concentrations. The survival of the moth from egg to adult when treated with the plant powders showed that there was significantly (p < 0.05) more adult in the control (71.3) compared to others. Extracts of all the tested plants were toxic to adult moth and also prevent hatching of the eggs of S. cerealella.