Physicochemical grain properties of wheat cultivars and insect biology drive resistance to Sitophilus oryzae L.

The rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), is a formidable global pest of storage grains. This study investigated how the interplay between the physicochemical grain parameters of wheat cultivars and the pest's physiological response modulates the resistance to the rice weevil. A forced-choice test evaluated the susceptibility of wheat cultivars based on parameters viz., percent weight loss of grains, adult emergence, mean developmental period, and susceptibility index. Among the wheat cultivars, HI 1544 and GW 322 were the least susceptible, while, PBW 343, HD 1563, and HI 8381 were highly susceptible. A significant positive correlation was noticed between percent weight loss and factors such as adult emergence, mean developmental period, total soluble sugars, starch, and insect digestive enzymes. In contrast, grain damage was negatively correlated with grain hardness, protein, amylolytic activity, and phenol content of grains. Principal component Analysis (PCA) accounted for 73.65% of the observed variation, effectively delineating key traits. Agglomerative Hierarchical Clustering (AHC) classified wheat cultivars into two categories based on their susceptibility to rice weevil. We recommend prioritizing less susceptible cultivars (e.g., HI 1544, GW 322) for breeding programs and infestation-prone regions. The findings emphasise that a holistic analysis of physicochemical and biological parameters offers a robust framework for screening resistance of wheat cultivars to rice weevil S. oryzae.