Tolerance in maize genotypes to the green-belly stink bug: methods of screening and biochemical responses in infested plants

ABSTRACT Identifying resistance sources using fast, sensitive, and standardized methods is key to initiating a breeding program or even a germplasm characterization. To establish the infestation density, the coexistence period, and discriminatory parameters for determining maize tolerance-type resistance to the green-belly stink bug, Diceraeus melacanthus (Hemiptera: Pentatomidae), greenhouse, and field trials were conducted using four maize genotypes (SCS154 Fortuna, SCS155 Catarina, 2B512 PW, and 2B610 PW). In both greenhouse and field trials, plants infested with a density of two adult stink bugs per plant for a coexistence period of seven days was determined to be the optimal conditions for evaluating maize genotypes tolerance. In addition, plant height and fresh weight were significantly reduced in infested plants on greenhouse trial. Conversely, D. melacanthus reduced plant height at the V5 stage and weight of thousand seeds in field trials, but plant height up to tassel, height of cob insertion, and grain yield were not affected, indicating a recovery potential of the tested genotypes. No difference in damage score was verified in the genotypes in both greenhouse and field trials. Biochemical responses of plants infested and non-infested with D. melacanthus from field trial indicated that chlorophyll and carotenoid content were reduced due to stink bug infestation. Moreover, infested plants expressed higher amounts of peroxidase and polyphenoloxidase enzymes. In field, the reduction in phenotypic and productive parameters was similar among the evaluated genotypes, and in general, the tested genotypes exhibited similar response to D. melacanthus attack.