Performance parameters of weevils (number of eggs laid, number of progeny, Dobie index, grain consumption) were negatively and significantly correlated (r = -0.8, P = 0.05) to the most abundant phenolic of grain, E-ferulic acid. The mechanism of resistance in maize to the stored product insects such as the maize weevil (MW), Sitophilus zeamais Motsch and the larger grain borer (LGB), Prostephanus truncatus Horn has been investigated in relation to secondary chemistry and other biochemical and physical characteristics of maize genotypes. Estimated parameters of genetic action for proteinase inhibitor concentration in endosperm were nonsignificant, The estimated genetic parameters for additivity of endosperm and dominance of pericarp associated with the expression of phenolic acid concentration in the grain were highly significant and inversely correlated to estimated susceptibility parameters of genetic action. The negative relationship of biochemical and biophysical traits of maize grain with feeding and reproductive activities of insects on the grain, suggests detrimental effects of these grain characteristics on the colonization success of insect populations. Resistance of pericarp-testa to compression forces was the only rheological trait of grain inversely correlated with susceptibility of maize to colonization by maize weevils, but neither the correlation coefficient nor the significance was high. However, the correlation between susceptibility of grain and contents of proteinase inhibitors in the endosperm is low, although negative and significant. Concentrations of phenolic acids in grain have a highly negative and significant correlation with indices of susceptibility of maize to the maize weevil. Inbred lines of quality protein maize (QPM), contrasting in resistance to maize weevil infestation, were used for the genetic analysis of resistance. The susceptibility of the grains to weevil infestation was measured by feeding, consumption and reproductive activities of insect populations. Specific traits associated with these grain tissues were: phenolic acids (pericarp, embryo), proteinase inhibitors (endosperm, embryo) and hardness of grain (pericarp, endosperm, embryo). The genetics of maize grain resistance to the maize weevil, Sitophilus zeamais Motsch., infestation was analyzed by means of additive linear models which considered genetic contributions of maize caryopsis through embryo, endosperm and pericarp.
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