# Phylogeography of Chinese White Pine Beetle Dendroctonus armandi (Coleoptera: Curculionidae: Scolytinae) in China

## TL;DR

This study explores the genetic history and population movements of the Chinese White Pine Beetle in China, revealing how climate and geography shaped its distribution.

## Contribution

The study identifies distinct genetic lineages and colonization routes of Dendroctonus armandi during the Late Pleistocene.

## Key findings

- Four haplogroups were identified in the Minshan, Qinling, Micang, and Ta-pa Mountains.
- QLM and TPM haplogroups experienced population expansion events.
- Three independent colonization routes were inferred for D. armandi.

## Abstract

Background: Dendroctonus armandi, an oligophagous beetle primarily infesting Pinus armandii, is geographically restricted and persistent in central China, causing significant ecological and economic losses. However, the intrinsic factors driving its continuous occurrence remain unclear. We examined the genetic variation patterns across the species’ range to explore its phylogeographic structure. Methods: We analyzed mitochondrial DNA sequence (mtDNA) data to assess population genetic structure and estimate the divergence times of distinct lineages. Results: Phylogenetic analysis identified four haplogroups corresponding to the Minshan (MSM), Qinling (QLM), Micang (MCM), and Ta-pa (TPM) Mountains. Demographic analyses revealed that QLM and TPM haplogroups have undergone population expansion events. Divergence time estimates indicated four lineages diverged during the Late Pleistocene. Notably, D. armandi may have followed two horizontal and one vertical independent colonization routes. The first route extended from MSM into QLM and then spread eastward along the QLM; the second route progressed from MSM into MCM and continued eastward into TPM; and the third route migrated southward from QLM into TPM. Conclusions: Climate oscillations, geographical isolation, and the patchy distribution of host trees collectively shaped the phylogeographic patterns of D. armandi. These findings elucidate the evolution and adaptability of D. armandi in mountainous environments.