Invasion of an inconspicuous ambrosia beetle and fungus may alter wood decay in Southeastern North America

Background: . Ambrosia beetles include well-known invasive pests, but most species established in non-native areas do not cause any significant impact. Here we report the recent invasion and rapid spread of Ambrosiodmus minor in the Southeastern US. Methods: : We used a combination of a multi-year survey, literature data on fungal symbionts from the beetle mycangia and in vitro bioassays of fungal competition, and extensive field observations of wood colonization patterns. Results: . In less than seven years, A. minor abundance has increased many-fold in Florida. The beetle is associated with an aggressive wood-rot fungus Flavodon ambrosius . Joint colonization of wood by A. minor and F. ambrosius results in extensive white rot (lignin removal). The invasion of this symbiosis may impact an ecosystem function previously considered not influenced by non-native ambrosia beetles: wood decay. We suggest monitoring of the impact of this invasion on native wood-inhabiting organisms, biomass degradation and the carbon cycle throughout the region.