Soluble phenolic content as an indicator of sorghum grain resistance to Sitophilus oryzae (Coleoptera: Curculionidae)

Eight land races of sorghum collected in Ethiopia were found to show significant variation by genotype in soluble phenolic content. Phenolic content, as catechin equivalents, was measured by the Prussian blue procedure. Variation in storage insect resistance was demonstrated using standardized tests with the rice weevil, Sitophilus oryzae. Significant inverse linear relationships were also found between resistance parameters such as weight loss of grain, the Dobie index of susceptibility, number of eggs laid and progeny emerged and the phenolic content of the grain (r2=0.85, 0.55, 0.46 and 0.52 respectively). The results suggest that the soluble phenolic content, which previous studies have shown to consist primarily of proanthocyanidins, can be used as an indicator of resistance