Abstract:
Exotic forest insects and their symbionts pose an increasing threat to forest health. This is apparently true for
the red turpentine beetle (Dendroctonus valens), which was unintentionally introduced to China, where the
beetle has killed millions of healthy native pine trees. Previous population genetics studies that used cytochrome
oxidase I as a marker concluded that the source of D. valens in China was western North America. In contrast,
surveys of fungi associated with D. valens demonstrated that more fungal species are shared between China and
eastern North America than between China and western North America, suggesting that the source population of
D. valens could be eastern North America. In this study, we used microsatellite markers to determine population
structure of D. valens in North America as well as the source population of the beetle in China. The analyses
revealed that four genetically distinct populations (herein named the West, Central, Northeast and Mexico)
represent the native range of D. valens. Clustering analyses and a simulation-based approximate Bayesian
computation (ABC) approach supported the hypothesis that western North America is the source of the invasive
D. valens population. This study provides a demonstration of non-congruence between patterns inferred by
studies on population genetics and symbiont assemblages in an invasive bark beetle.
