Corn physicochemical properties affect Sitophilus zeamais losses

The maize weevil, Sitophilus zeamais Motschulsky, 1885 (Coleoptera: Curculionidae), is one of the primary insect pests affecting maize in Brazil. Due to the limited availability of active compounds for insect control, there is a pressing need to explore alternative sources of resistance, potentially harboring genetic reservoirs for material improvement. This study aimed to identify resistant maize varieties by assessing S. zeamais emergence, amylase enzyme inhibitors, susceptibility indices, and nutritional analysis of the grains. Eight maize varieties, namely Azteca, Caiano, Colorado, Maisena, Oaxaca, Oito Carreira, Palha Roxa, and Rajado, were evaluated. Unsexed S. zeamais adults were confined in 250 mL plastic bottles containing grains of each maize variety for ten days, with ten replications for copulation and oviposition. After the incubation period, the insects were removed, and the infested grains stored for an additional thirty days. The emergence of S. zeamais was monitored every two days, and the pots were discarded after three consecutive evaluations without emergence. The amylase enzyme inhibitors, as a potential factor influencing resistance, was also analyzed. The susceptibility index was the primarily parameter used to evaluate resistance of maize varieties to S. zeamais adults. The Colorado, Oaxaca, and Oito Carreira maize varieties were resistant through antibiosis and the Azteca, Caiano and Rajado were moderately resistant. In contrast, the Maisena and Palha Roxa varieties were susceptible to S. zeamais. The Azteca variety was moderately resistant, despite its high levels of amylase enzyme inhibitors.