Development of insect resistance to insecticidal toxins from Bacillus thuringiensis (Bt) threatens the sustainable application of Bt-biotechnology in agriculture. Identification and understanding of Bt resistance-conferring gene mutations in insects are fundamentally critical for development of resistance management tactics. The cabbage looper, Trichoplusia ni, has developed resistance to Bt sprays in commercial greenhouses, and the resistance to the Bt toxin Cry1Ac has been identified to be associated with a frameshift insertion in the ABCC2 gene and additional resistance-conferring mutation(s) to be identified. In this study, the second Cry1Ac resistance gene in T. ni was localized to a linkage group by linkage analysis using chromosome specific markers and whole genome resequencing. The resistance locus was further mapped in the linkage group by amplicon sequencing (AmpSeq)-based linkage mapping.
