Ambrosia beetle habitat use, host use, and influence on early wood colonizing microbes

Despite the potential of exotic ambrosia beetle species to transform forest communities by vectoring fungal pathogens, little is known regarding their influence on microbe communities or how forest characteristics influence ambrosia beetle communities. We aimed 1) to characterize the ambrosia beetle community in an oak-hickory forest, 2) to investigate the influence of forest stand and site characteristics, coarse woody debris (CWD) microclimate, and CWD size on ambrosia beetle abundance and richness, and 3) to explore how Xylosandrus crassiusculus Motschulsky galleries in wood altered microbe diversity and abundance. We collected ambrosia beetles in aerial traps for 2 years and eclector traps for 3 months, and we isolated microbes from wood with and without X. crassiusculus galleries for 12 months. Thirteen native and seven exotic ambrosia beetle species occurred in a central Missouri oak-hickory forest.

Regardless of stand and site characteristics, the exotic component made up 85 – 87% of the ambrosia beetles collected. Older stands had more ambrosia beetles and species per trap than younger stands. In addition, stands with structural characteristics consistent with later succession stages had more native ambrosia beetles. Larger CWD had more ambrosia beetles and more species than smaller diameter CWD while CWD microclimate and site aspect did not influence abundance. Also, microbes were more likely to occur and more fungal morphotypes occurred in wood with galleries than wood without galleries during the first 6 months. Potentially, alterations to forest characteristics influence ambrosia beetle abundance and thus indirectly affect early microbe community formation in wood.