Influence of temperature and maize genotypes on the population dynamics of Sitophilus zeamais Motschulsky 1885 (COLEOPTERA: CURCULIONIDAE) and grain quality during storage

Abstract

Post-harvest losses in maize caused by Sitophilus zeamais represent a significant challenge to global grain storage systems. This study investigated the effects of temperature and corn genotype on S. zeamais population dynamics during six months of storage. Eight maize genotypes (Nutricional Embrapa, Cinquentinha, Palha Roxa, Sol da Manhã, Roxo, BR 451 QPM, Catingueira, and Asteca Vermelho) were evaluated under four temperature regimes (15, 20, 25, and 30 °C). Parameters assessed included insect emergence, weight, grain weight loss, and residual weight. Chemical composition (starch, protein, and lipid content) was analyzed to explore potential resistance mechanisms. Temperature significantly influenced S. zeamais development. Low temperatures (15 °C) suppressed insect emergence and grain degradation across all genotypes, while higher temperatures (25–30 °C) amplified pest activity, particularly in susceptible genotypes (Cinquentinha, Palha Roxa). Resistant genotypes (Nutricional Embrapa, Asteca Vermelho) consistently demonstrated reduced insect emergence, weight, and grain losses, likely due to enhanced kernel hardness, biochemical defenses, and nutritional profiles. Lipid and protein content varied significantly among genotypes, influencing pest feeding efficiency and reproduction. Susceptible genotypes showed higher weight loss and residual grain mass, exacerbated by fungal contamination at higher temperatures. The integration of resistant genotypes and temperature management effectively mitigates S. zeamais infestations, preserving grain quality and reducing post-harvest losses. These findings underscore the importance of genotype selection in integrated pest management and highlight the need for further research into the genetic and biochemical traits associated with resistance. Combining resistant genotypes with sustainable storage practices offers a promising strategy for grain preservation in diverse environmental conditions.