Abstract: The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important insect pest in cruciferous vegetables and has developed high resistance to avermectin all over the world. In this study, AFLP was used to construct a linkage map of resistance to avermectin in diamondback moth. The mapping families consisted of the susceptible strain, the abamectin-resistant strain and their backcross progeny. A total of 1 044 DNA bands and 271 polymorphic loci were amplified using 10 combinations of AFLP primers. Chi-square (χ²) analysis indicated that only 123 bands fit the segregation ratio of 1∶1 (P=0.05) in these polymorphic loci. Twenty-eight linkage groups were constructed with 112 bands, covering about 1 222.7 cM of the genomics of the diamondback moth. Three markers of E1M4-15, E1M1-4, and E1M4-2, linked with abamectin-resistant gene were situated on the same linkage group and their distance apart from resistant gene was 0 cM, 8.3 cM, and 13.1 cM, respectively. Comparison with the constructed linkage map showed that the gene was located on the fifth linkage group. These AFLP markers associated with resistance to abamectin show a strong potential of application in monitoring diamondback moth resistance to abamectin.

Key words: Plutella xylostella, abamectin, resistance gene, AFLP marker