Tarbiat Modares University Journal of Agricultural Science and Technology 1680-7073 Articles in Press 2025 09 16 Genetic structure and diversity of the beet armyworm Spodoptera exigua (Hübner) (Lepidoptera, Noctuidae) in Iran 24113 EN Somayeh Ebrahimi Shahid Chamran University of Ahvaz Mehdi Esfandiari Shahid Chamran University of Ahvaz Lida Fekrat Ferdowsi University of Mashhad Journal Article 2025 09 16 <span>Spodoptera exigua</span><span> is a significant agricultural pest in Iran. In this research, we </span><span>analysed </span><span>a 700 base pair DNA fragment of COI to assess the genetic diversity of this harmful pest. In total, 54 specimens were sampled across six Iran’s geographic areas, revealing six distinct haplotypes. The overall populations exhibited low genetic diversity (h = 0.463 ± 0.068, π = 0.00096 ± 0.00017). No distinct geographic pattern was observed in the haplotype distribution, as indicated by phylogenetic and median-joining network analyses. The median-joining network of Iranian haplotypes, combined with sequences from other global regions, demonstrated a lack of geographical clustering, with Hap.₁ as the most prevalent haplotype spanning Iran, Europe, Asia, and Australia, indicative of extensive gene flow and shared evolutionary history. The Fst values for the Iranian populations ranged from -0.12240 to 0.07189, revealing no significant differentiation among the populations. Analysis of molecular variance showed a larger proportion of the variation within rather than between them, after 1000 random permutations, the level of population differentiation was found to be non-significant. The combination of an unimodal mismatch distribution and the non-significant results of Tajima's D (D = 0.02011, P > 0.05) and Fu's Fs (Fs = 3.33384, P > 0.05) suggested the beet armyworm may have expanded recently (~10,000–50,000 years ago) but has returned to a state resembling neutrality without significant selection pressures acting on it. Insights from this population genetic study can aid in crafting targeted approaches for managing this extensively migratory pest.</span> <br> https://jast.modares.ac.ir/article_24113_5d2592e8bab5112c7d161e133eade524.pdf