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Title: The identification and use of semiochemicals for the control of the maize weevil, Sitophilus zeamais (Motschulsky) in Nigeria
Author: Ukeh, Donald A.
ISNI:       0000 0004 2668 3022
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2008
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Studies were carried out to evaluate the repellent properties of the seeds of alligator pepper, Aframomum melegueta and Black pepper, Piper guineense, and ginger, Zingiber officinale rhizomes against S. zeamais. In 4-way olfactometry bioassays, S. zeamais adults showed strong attraction to maize and wheat seed volatiles but were significantly repelled by odours emanating from the seeds of A. melegueta, P. guineense and Z. officinale rhizomes. In field trials crushed A. melegueta seeds and Z. officinale rhizomes, significantly repelled S. zeamais from traditional maize granaries with treated maize cobs giving higher germination than untreated cobs. Laboratory reproductive potential studies showed that A. melegueta and Z. officinale powders caused significant adult mortality and reproductive potential deterrence against S. zeamais resulting in a reduction in F1 progeny emergence. Olfactometer bioassays also confirmed that vacuum distilled A. melegueta and Z. officinale extracts and oleoresins were repellent towards adult S. zeamais when tested alone, and in combination with maize grains. Bioassay-guided liquid chromatography of the distillates showed that fractions containing polar compounds accounted for the repellent activity. Coupled gas chromatography-mass spectrometry (GC-MS), followed by GC peak enhancement and enantioselective GC using authentic compounds, identified 3 major compounds in the behaviourally active A. melegueta fraction to be (S)-2-heptanol, (S)-2-heptyl acetate and (R)-linalool in the ratio 1:6:3. Z. officinale had 1,8-cineole, neral and geranial in the ratio of 5.48:1:2.13. The identification of these behaviourally active compounds provides a scientific basis for the observed repellent properties of A. melegueta and Z. officinale extracts, and demonstrates the potential for their development in stored-product protection at the small-scale level in Africa.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Plant protection ; Insect pests