Susceptibility of old and modern wheat genotypes to Sitophilus granarius (L.) and Rhyzoperta dominica (F.)

The granary weevil, Sitophilus granarius (L.), and the lesser grain borer, Rhyzopertha dominica (F.), are among the major primary pests of stored cereals worldwide. The development of resistant wheat varieties to insect attacks during postharvest is a potential alternative to chemical insecticides. The rediscovery of old wheat genotypes could represent a source of income for farmers, especially in agriculturally marginal areas, and it is also a way to safeguard these valuable genetic resources, useful for breeding purposes. In this study, the susceptibility of three old genotypes (Senatore Cappelli, old Saragolla, and Dauno III) and four modern wheat varieties (Mec, Ofanto, Svevo, and Faridur) towards S. granarius and R. dominica was evaluated. All wheat varieties were susceptible to attacks by both species, however some significant differences among them were recorded. Using a scale 0 to >= 11, in which 0 is resistance and >= 11 highly susceptible, the Susceptibility Index (S.I.) of Faridur (14.9) to S. granarius was significantly higher than those of Dauno III (11.1) and Senatore Cappelli (10.5), whereas the S.I. of Faridur (12.6) to R. dominica was significantly higher than those of Dauno III (11.2) and Ofanto (11.0). Wheat susceptibility to stored grain pests probably is the result of different physicochemical features and their interactions. Among them, kernel hardness seems to be the first barrier to S. granarius and R. dominica attacks. In addition, lesser susceptible varieties to both species showed a higher protein content. Furthermore, wheat varieties with a higher thousand-kernel mass were more susceptible to the lesser grain borer, whilst it did not influence the susceptibility to the granary weevil. Due to the increasing interest of consumers and farmers in old grains, the present study offers new knowledge useful for a more rational postharvest management of these cereal resources.