Fall armyworm Spodoptera frugiperda (J. E. Smith) and sugarcane stem borer Diatraea saccharalis are the major lepidopteran pests in maize crop in Brazil. Genetically modified maize that expresses insecticidal protein(s) of Bacillus thuringiensis (Bt) Berliner have been used to control these pests. Most of Bt maize events that are commercially approved in Brazil Express Cry proteins of Bt. In 2009, the National Biosafety Commission (CTNBio) approved the Bt maize MIR 162® that express a vegetative insecticidal protein VIP3Aa20. The target-pests of MIR 162® are S. frugiperda and D. saccharalis. It is known that the target site of of this vegetative insecticidal protein is distinct from the Cry proteins, thus VIP3Aa20 can be an important tool in the Insecticide Resistance Management (IRM) programs. To preserve the lifetime of Bt maize, one of the major problem is the risk of resistance evolution of the target pests to Bt proteins. Therefore, in order to implement a proactive resistance management program to MIR 162® to avoid or delay the resistance evolution, the objetives of this reserarch are to establish baseline susceptibility studies of S. frugiperda and D. saccharalis to VIP3Aa20 protein, to evaluate the geographical variability in the susceptibility to VIP3Aa20 in populations of S. frugiperda and D. saccharalis collected from major maize-producing regions and to check whether the MIR 162® can be considered a high-dose event to both target pests.
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