Mariner or mariner-like element (MLE) is a Class II transposable element that is widely distributed in many eukaryotes including insects.  We report a preliminary study of population genetics of MLE in pink bollworm (Pectinophora gossypiella S.) a notorious cotton pest. Transposable element mediated transgenic pink bollworm are being developed to improve sterile insect technique (SIT). Understanding the evolutionary history of transposable element in the pink bollworm is an important component in risk assessment of the transgenic pink bollworm. We identified MLEs in the pink bollworm by genomic Southern blotting and degenerate PCR. The MLEs belong to cecropia subfamily, and have the highest identity with the MLE in Indian tasar silkmoth Antheraea mylitta (up to 83% identity). Partial sequences obtained for different copies of MLE encode incapacitated transposases disrupted by deletions and stop codons. Analyses of nucleotide sequences found 41 to 76 % identity among the MLEs. The study is being expanded to examine the MLEs in the populations of pink bollworm from different geographical origin to understand the evolutionary history of the MLEs in the pink bollworm.