Toxicity of Bt Protein on Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) Fed With Corn Leaves in Paraguay

The fall armyworm Spodoptera frugiperda is the most destructive pest in corn cultivation in Paraguay with yield losses of 20 to 70%. The adoption of genetically modified crops (GMO) is a valid technique for managing this pest. The objective of this investigation was to evaluate the toxicity among Bt events used locally; determining mortality and important biological parameters. The S. frugiperda population previously collected from the field was raised under laboratory conditions fed with leaves from events MIR162TM (Vip3A19), VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb), PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) and a treatment with non-maize. Bt BR106TM. The mortality of 120 larvae was evaluated for each treatment and the viability until the adult stage of those larvae that managed to survive the different treatments was observed. A high toxicity effect was verified with 100% mortality of neonatal larvae fed with the MIR162TM (Vip3A19) event; as for the other events, 86% and 61% VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb), and PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) respectively; with 13% mortality for the non-Bt control variety BR106TM. The oviposition period, viability and number of eggs laid in adults surviving the PowerCoreTM (Cry1A105, Cry1F, Cry2Ab2) and VT3ProTM (Cry1A105, Cry2Ab2, Cry3Bb) events were reduced, affecting the fecundity of the surviving insect population.