Evaluation of resistance to Spodoptera frugiperda in sweet and field corn genotypes.
Maize can be affected by different pest damages throughout the crop cycle. Some insects are harmful, among which the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae), is considered the most deleterious pest, for attacking plants of both field and sweet corn plants in all stages. Thus, the use of resistant genotypes has become an important strategy in integrated pest management and highly valued in plant breeding programs. However, information regarding the impact of pests on sweet corn is scarce, requiring studies on possible resistant genotypes. The objective of this study was a laboratory evaluation of the resistance of 10 sweet corn genotypes and two controls of field corn (BRS 1030 and Zapalote Chico), as well as the damage caused by Spodoptera frugiperda, by means of multivariate analysis. A completely randomized experimental design with 27 replications was used. Eighteen traits were evaluated during the whole caterpillar cycle, including biological traits and indices of consumption and food use. After the multicollinearity diagnosis, only six traits were maintained for the canonical analysis and factor analysis as well as UPGMA clustering, which differentiated the 12 genotypes in three groups. The canonical analysis explained 89% of the total variation among the six traits and factor analysis divided the traits in two factors. The results showed that the sweet corn genotypes, Teea Dulce, MG 161, Doce Flor da Serra, Doce Cubano and Tropical Plus, tend to have antibiosis as resistance mechanism to fall armyworm due to the low consumed leaf area and the impaired insect development.