EFICÁCIA DA PROTEÍNA VIP3AA NO MANEJO DE Spodoptera frugiperda EM ALGODOEIRO

Abstract

The fall armyworm (Spodoptera frugiperda) is considered one of the most significant agricultural pests in Brazil, particularly affecting cotton crops grown under conventional production systems. To reduce the damage caused by this insect and to enhance management efficiency, genetically modified varieties expressing the insecticidal Bacillus thuringiensis (Bt) protein were developed, offering a more effective control alternative. However, the improper use of this technology, especially the absence or incorrect implementation of refugees, has favored the development of resistant populations in response to the available Bt technologies. The objective of this study was to evaluate the efficacy of the Vip3Aa protein in controlling Spodoptera frugiperda in cotton cultivars. To this, larvae collected in Luís Eduardo Magalhães, Bahia, were compared with a reference population from Embrapa, both maintained on conventional cotton plants and Bt cotton plants. The parameters assessed included larval duration, viability, and survival under the treatments analyzed. The results demonstrated the high effectiveness of the Bt technology (Vip3Aa) in controlling Spodoptera frugiperda originating from Luís Eduardo Magalhães, Bahia. A significant mortality rate was observed in larvae fed with Bt cotton leaves and floral buds, reaching levels close to 100% after 168 hours of exposure, in contrast to the low mortality recorded in conventional cotton. Contrary to the initial hypothesis, no substantial survival was detected that would indicate established or emerging resistance in this field population. Consequently, due to the high susceptibility of the evaluated population, it was not possible to assess the fitness cost associated with resistance to the Vip3Aa protein in this study, as the primary condition (the presence of resistant individuals) was not met. The findings reinforce that this technology remains effective in the region; however, continuous monitoring and resistance management practices—such as the use of refuge areas—remain essential to preserving its long-term efficacy.