Induction of resistance to fall armyworm (Spodoptera frugiperda) (Lepidoptera: Noctuidae) in transgenic and conventional corn plants

Abstract

The fall armyworm (Spodoptera frugiperda) is an important pest of corn in Brazil. Insecticides are applied to reduce the losses caused by this pest. Integrated control methods, including resistance induction in plants using silicon and transgenic hybrids, must be used to reduce the impacts caused by insecticide application. The aim of this study was to assess the effects of calcium silicate application (CaSi4) to the sowing furrow on S. frugiperda damage to and incidence on conventional and transgenic genotypes with different Bt technologies. The treatments were arranged in a randomized block design in a 3x4x4 factorial scheme with three corn hybrids, Morgan 30A91 PRO Power Core (Cry1F, Cry1A105, Cry2Ab2 Bt toxin), Morgan 20A55 Herculex (Cry1F Bt toxin) and AG 1051 (conventional); four silicon doses, 0, 300, 600 and 900 kg. ha-1 calcium and magnesium silicate (Agrosilicio Plus, Ca = 25%, Mg = 6%, Si = 10.5%); and four assessment times, 15, 30, 45 and 60 days after emergence (DAE). Four replicates were performed. The mean number of caterpillars per plant, damage caused by S. frugiperda, and production components were assessed. Calcium and magnesium silicate application induced resistance in corn plants, thus reducing the damage caused by S. frugiperda. Corn responded to resistance induction with increasing doses of calcium and magnesium silicate. The transgenic hybrid with three proteins (Morgan 30A91 PRO) improved protection against S. frugiperda. The interaction between silicate fertilization and transgenics produced a synergistic effect, suggesting a viable alternative for S. frugiperda control.