Joseph C. Onyilagha

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A suite of commercially available volatile compounds was tested in an olfactometer bioassay for responses by the crucifer flea beetle (Phyllotreta cruciferae). Flea beetles were inhibited by exposure to hexane, pentane, and ethanol. Allyl-isothiocyanate, a crucifer-specific volatile, was moderately attractive to spring and early fall flea beetles, but(More)
Two numerical taxonomic techniques, single linkage cluster analysis (SLCA) and principal components analysis (PCA) were used to study the relationship between Dioscorea cayenensis and D. rotundata cultivars. The study was prompted by the confusion in the taxonomy of the two taxa. Twenty-two cultivars (14 of D. rotundata and 8 of D. cayenensis) were(More)
The applicability of some existing droplet sedimentation theories to erythrocyte suspensions was investigated using glutaraldehydefixed erthrocytes from horse, canine, pig, chicken, and human. The Svensson criteria were shown to underestimate the load supportable by a density gradient. The available theories on droplet formation times could not predict each(More)
The taxonomy of edible Colocasia (Cocoyam) is confusing. The existence of one species, C. esculenta var. antiquorum or C. esculenta and C. antiquorum as two separate species is controversial. Nine high yielding Nigerian cultivars of cocoyam made up of members of the two taxa were grown under the same environmental conditions. As a preliminary investigation,(More)
Thirty-seven flavonoid compounds (9 flavones, 18 flavonols, 8 flavanones, and 2 flavanonols) were investigated for their effect on feeding choice with bertha armyworm (Mamestra configurata Walker; BAW). Feeding choice was dependent upon subtle differences in biochemical structure. Unsubstituted flavone and flavanone were the strongest feeding deterrents in(More)
In order to identify the major characters which account for variation among Dioscorea rotundata, 14 high yielding accessions were studied using Single Linkage Cluster Analysis (SLCA) and Principal Component Analysis (PCA). The accessions were planted under the same environmental conditions for 3 years. Altogether, 40 characters were selected and coded for(More)
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