Toxic Bait as an Alternative Tool in the Management of Spodoptera frugiperda in Second Corn Crops

Managing the fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith, 1797), has been increasingly difficult owing to the increase in individual resistance to insecticides and genetically modified Bacillus thuringiensis (Bt) plants. This study used the attracting and killing method to control FAW adults in the field by spraying Noctovi® with methomyl insecticide. The experiments were conducted in commercial cornfields, non-Bt and Bt crops, over two agricultural years (2018 and 2019) at eight sites distributed in three cities located in the south of Mato Grosso do Sul State, Brazil. The following six insecticide treatments were used: spraying in continuous bands spaced every 100, 50, and 25 m; intermittent spraying every 25 m; control (without insecticide application); and spraying the entire area with insecticide (positive control). Food bait associated with the insecticide molecule was applied to the crop at vegetative stages V1 and V3, and the adult population size and level of leaf damage caused by the caterpillars (assessed via the Davis scale) were evaluated. The application of toxic bait in bands with spacing less than or equal to 50 m significantly reduced the percentage of damage to the plants, with the effect stronger in Bt crops. We suggest that the control of FAW adult populations would be more efficient if the attracting and killing technique was incorporated in integrated pest management programs for second corn crops.