Resistance grade of different Triticum species toward Sitophilus oryzae L. (Coleoptera: Curculionidae)

Varietal resistance in cereals represents a promising and sustainable strategy for managing biotic stressors, including insect pests during storage. In this study, eighteen genotypes from six cereal species-Triticum monococcum, T. dicoccum, T. spelta, T. durum, T. aestivum, and Triticosecale-were evaluated for their resistance to the rice weevil, Sitophilus oryzae L., one of the most destructive stored product pests. The objective was to assess differences in susceptibility by measuring some insect parameters, such as adult mortality, F1 progeny production and body size, along with grain traits such as kernel hardness and weight. For this scope, bioassays included both non-choice and two-way choice tests to evaluate insect performance and preference. Significant inter-and intra-specific variation in susceptibility was observed. In non-choice bioassays, Sitophilus oryzae generally showed higher adult mortality and lower adult progeny emergence feeding and ovipositing on T. durum and T. dicoccum genotypes, suggesting greater resistance of these genotypes; on the contrary T. monococcum and triticale appear more susceptible. Grain hardness was strongly and negatively correlated with adult progeny output, supporting its role as a mechanical barrier to larval development. However, kernel hardness did not influence adult body size, suggesting that individuals overcoming this barrier can still complete normal development. Kernel weight showed a positive correlation with female size, indicating a potential fitness advantage for the insects feeding on larger seeds. In two-choice assays, S. oryzae showed a preference for softer genotypes, particularly triticale Agostino and Tribeca, over harder genotypes such as durum wheat Perciasacchi and Aureo. These results provide new insights into the resistance potential of traditional and modern Triticum genotypes. The integration of resistant genotypes, especially from T. durum and T. dicoccum, into breeding programs and storage systems may contribute to reducing chemical inputs and improving long-term grain protection strategies.