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

Abstract

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.

Relationships among wood‐boring beetles, fungi, and the decomposition of forest biomass

“…For example, several Asian species of the ambrosia beetle genera Ambrosiodmus and Ambrosiophilus have been introduced to multiple continents where they have thrived. Unlike all other ambrosia beetles known, these beetles farm an ambrosia fungus that is an aggressive wood‐decayer which can exclude native fungi, and thus these introduced beetles could potentially offset the effects of native beetles on decay rates (Hulcr, Skelton, Johnson, Li, & Jusino, ; Kasson et al, ; Skelton, Loyd, et al, ). Continued studies of how beetle‐associated fungi interact with free‐living fungi in decaying wood will help clarify the total impact of bark and ambrosia beetle introductions on ecosystem processes in native forests.…”

Experimental evidence that fungal symbionts of beetles suppress wood decay by competing with decay fungi

“…Given that Flavodon-farming beetles have been widely introduced, are becoming widely established within their population, rapidly increasing in some areas along with their exotic aggressive pioneer wood decay fungus (Hulcr et al 2018), these series of events could likely have a substantial impact on decomposition and the turnover of forest biomass, nutrients, and carbon.…”

“…Several species of Ambrosiodmus are native to the southeastern US, and at least three species are non-native. An Asian ambrosia beetle, Ambrosiodmus minor, was first detected in Florida by state monitoring efforts in 2011, and has since become one of the most frequently collected species across the state where it infests many species of hardwood and coniferous trees (Hulcr et al 2018). Although there have been more than 50 introductions of bark and ambrosia beetles in the United States (http:www.barkbeetles.info; accessed Oct 15, 2018), A. minor is particularly likely to affect wood decomposition because of the combination of its increasing abundance and its symbiotic wood-decay fungus.…”

The Essential Role of Taxonomic Expertise in the Creation of DNA Databases for the Identification and Delimitation of Southeast Asian Ambrosia Beetle Species (Curculionidae: Scolytinae: Xyleborini)

“…Most introduced species have an apparently benign effect on the environment because most non-native species occupy woody debris unused by the meager native Holarctic xyleborine fauna (Wood, 1982;Knížek, 2011;Hulcr et al, 2017). However recent findings suggest that the native wood decay fungus community may be displaced by a non-native fungus proliferated by a nonnative xyleborine (Hulcr et al, 2018). In addition, three species, Euwallacea fornicatus, Euwallacea perbrevis, and Xyleborus glabratus, and their associated fungi have caused economic and ecological destruction to US orchards and natural forests.…”