Laboratory selection of Bt-resistant fall armyworm (Spodoptera frugiperda): Investigating epigenetic mechanisms and their role in resistance development and management

The fall armyworm (Spodoptera frugiperda) is a well-known polyphagous pest, widely targeted by transgenic Bt crops. Although Bt resistance development in insect pests has been extensively studied, the biological mechanisms enabling the resistance evolution to have been focused only on the associated classical gene mutations. In this study, we established five homogeneous susceptible inbreds of S. frugiperda using single-pair mating from a known laboratory Bt susceptible strain for two generations. Resistance selection was initiated through continuous exposure to the five susceptible inbreds to low doses of Cry1A.105 Bt protein with increasing selection concentrations over time. Standardized bioassays are being conducted across generations to monitor changes in the Bt susceptibility of the five inbreds. Our hypothesis is that resistance may also arise from epigenetic regulation—allowing individuals without classical mutations in resistance alleles to survive through reversible or heritable changes in gene expressions. By exploring non-genetic contributions to resistance evolution, this research aims to broaden our understanding of adaptation in pest populations to control measures. Insights gained may enhance resistance monitoring programs and support integrated insecticide resistance management (IRM) strategies that address both genetic and epigenetic factors, ultimately helping to preserve the efficacy of Bt crop technology for pest management.