Factors contributing to resistance of exotic maize populations to maize weevil,Sitophilus zeamais

Factors contributing to resistance of maize to infestation by the corn weevilSitophilus zeamais were investigated in four populations of indigenous and improved maize from Belize. Resistance was related to the antifeedant properties of grain as well as sugar content and mechanical hardness. Grain extracts of all populations of maize significantly reduced insect feeding on treated artificial diets when compared to control diets. Consumption of treated diets was negatively correlated with phenolic content of the grain extract. An analysis by GC-MS indicated that ferulic acid andp-coumaric acid were the principal phenolics present in the extracts, and insect feeding was strongly deterred when pure substances were added to insect diets. Fluorescence associated with ferulic acid and related compounds in grain sections was located in the pericarp and aleurone layer and was especially intense in the most resistant grain variety.