Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on Apr. 14, 2009). Includes bibliographical references.

Studies were carried out to evaluate the repellent properties of the seeds of alligator pepper, <i>Aframomum melegueta </i>and Black pepper, <i>Piper guineense, </i>and ginger, <i>Zingiber officinale </i>rhizomes against <i>S. zeamais</i>. In 4-way olfactometry bioassays, <i>S. zeamais</i> adults showed strong attraction to maize and wheat seed volatiles but were significantly repelled by odours emanating from the seeds of <i>A. melegueta</i>, <i>P. guineense</i> and <i>Z. officinale</i> rhizomes. In field trials crushed <i>A. melegueta </i>seeds and <i>Z. officinale </i>rhizomes, significantly repelled <i>S. zeamais</i> from traditional maize granaries with treated maize cobs giving higher germination than untreated cobs. Laboratory reproductive potential studies showed that <i>A. melegueta </i>and <i>Z. officinale </i>powders caused significant adult mortality and reproductive potential deterrence against <i>S. zeamais</i> resulting in a reduction in F₁ progeny emergence. Olfactometer bioassays also confirmed that vacuum distilled <i>A. melegueta</i> and <i>Z. officinale </i>extracts and oleoresins were repellent towards adult <i>S. zeamais</i> 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 <i><span style='text-transform:uppercase'>A. melegueta </i>fraction to be (<i>S)</i>-2-heptanol, (<i>S)</i>-2-heptyl acetate and (<i>R)</i>-linalool in the ratio 1:6:3. <i>Z. officinale</i> 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 <i><span style='text-transform:uppercase'>A. melegueta </i>and <i>Z. officinale </i>extracts, and demonstrates the potential for their development in stored-product protection at the small-scale level in Africa.