Genetic variability of Helicoverpa armigera (Hübner) attributable to cadherin gene-specific molecular markers

CrylAc resistance in the American bollworm, Helicoverpa armigera is associated with alteration in midgut cell adhesion protein, cadherin. Genetic diversity of cadherin gene was studied using molecular markers developed from cDNA sequences of H. armigera. Six out of eight pairs of molecular markers were able to amplify the cadherin gene in eighteen insect populations collected from different locations in India and produce a total of 218 amplicons. The maximum similarity (96%) was found for three pairs of insect populations from Rajkot and Sirsa, Akola and Bhatinda, and Faridkot and Karnal; while the minimum similarity (82%) was for the pair of insect populations from Nanded and Hyderabad. The study showed 4-18% genetic diversity in cadherin-specific gene of H. armigera populations which differed at least 100-fold in their susceptibility to CrylAc.