1 Invasion of an inconspicuous ambrosia beetle and 2 fungus may alter wood decay in Southeastern North 3 America 4 5 Jiri Hulcr1,2, James Skelton1, Andrew J. Johnson1, You Li1, Michelle A. Jusino1,3 6 7 1 School of Forest Resources and Conservation, University of Florida, Gainesville, FL, USA 8 2 Entomology and Nematology Department, University of Florida, Gainesville, FL, USA 9 3 Department of Plant Pathology, University of Florida, Gainesville, FL, USA 10 11 Corresponding Author: 12 Jiri Hulcr1 13 UF/IFAS School of Forest Resources and Conservation, PO Box 110410, Gaiensville, FL, 14 32611, USA 15 Email address:
[email protected] 16 17 Abstract 18 Background. Ambrosia beetles include well-known invasive pests, but most species established 19 in non-native areas do not cause any significant impact. Here we report the recent invasion and 20 rapid spread of Ambrosiodmus minor in the Southeastern US. 21 Methods: We used a combination of a multi-year survey, literature data on fungal symbionts 22 from the beetle mycangia and in vitro bioassays of fungal competition, and extensive field 23 observations of wood colonization patterns. 24 Results. In less than seven years, A. minor abundance has increased many-fold in Florida. The 25 beetle is associated with an aggressive wood-rot fungus Flavodon ambrosius. Joint colonization 26 of wood by A. minor and F. ambrosius results in extensive white rot (lignin removal). The 27 invasion of this symbiosis may impact an ecosystem function previously considered not 28 influenced by non-native ambrosia beetles: wood decay. We suggest monitoring of the impact of 29 this invasion on native wood-inhabiting organisms, biomass degradation and the carbon cycle 30 throughout the region.