Repellent activity of alligator pepper, Aframomum melegueta, and ginger, Zingiber officinale, against the maize weevil, Sitophilus zeamais.
The repellent activity of alligator pepper, Aframomum melegueta, and ginger, Zingiber officinale (Zingiberaceae), against the maize weevil, Sitophilus zeamais (Coleoptera: Curculionidae), was investigated in four-way olfactometer bioassays. Results showed that vacuum distilled A. melegueta and Z. officinale extracts were repellent towards adult S. zeamais both in the absence and the presence of maize, Zea mays, grains. Bioassay-guided liquid chromatographic fractionation of the distillates showed that fractions containing oxygenated 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 fractions of A. melegueta and Z. officinale to be (S)-2-heptanol, (S)-2-heptyl acetate and (R)-linalool in a ratio of 1:6:3, and 1,8-cineole, neral and geranial in a ratio of 5.48:1:2.13, respectively. The identification of these behaviourally active compounds provides the scientific basis for the observed repellent properties of A. melegueta and Z. officinale, and demonstrates the potential for their use in stored-product protection at the small-scale farmer level in Africa.
Ukeh
Donald A
DA
School of Biological Sciences, University of Aberdeen, Aberdeen, United Kingdom.
Birkett
Michael A
MA
Pickett
John A
JA
Bowman
Alan S
AS
Luntz
A Jennifer Mordue
AJ
D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D007302:Insect Repellents / Q000494:pharmacology*; D048889:Weevils; D030521:Zingiberaceae
D007302:Insect Repellents