The forests of the Zagros, with an area of 6 million hectares, make up 40% of Iran's forests. The forests include different oak species. In recent decades, Tortrix viridana L. has caused extensive defoliation in almost all the deciduous oak forests, increasing oak decline in some areas. The young larvae bore inside flushing buds, and in order to develop, they need to have good phonological synchronization with the budburst phase of their host plant. The intensity of feeding and high damage appeared in the fourth and fifth larval ages, such that in some cases the trees are completely devoid of leaves. The genetic diversity of the T. viridana on two host oak species, which are Quercus brantti and Q. infectoria was investigated using the D-LOOP region sequence of mitochondrial DNA in some Zagros forests. The samples included 72 species of oak moths that were collected separately from the mentioned hosts from 17 forest areas in the provinces of West Azarbaijan, Lorestan, Kurdistan and Kermanshah. The collected samples, which were in the larval stage, were grown in laboratory conditions until they turned into pupae and then into complete insects for DNA extraction. Twenty populations were selected to investigate genetic diversity using the mitochondrial genome, and 11 population DNAs were of suitable quality for further investigations. In order to amplify the mitochondrial D-LOOP region, based on the sequence obtained from the NCBI site, a primer pair was designed that amplified a fragment of 1036 base pairs. The desired region in the collected samples was amplified using the PCR method, and the resulting product was sequenced. The sequences were edited using Bioedit software and aligned with the help of MegaX software, and the phylogenetic tree was drawn by the neighbour-joining method with 1000 sampling repetitions. The results of this study showed the low genetic diversity between populations of different geographical regions and the existence of intra-population diversity as well as the existence of diversity between populations based on different hosts. Marker D-LOOP showed the presence of 5 haplotypes in these populations. The presence of low diversity between populations indicated the existence of gene flow between populations and spatial and host adaptation in the studied populations.
