Ambrosia beetle communities in forest and agricultural ecosystems with laurel wilt disease

The invasive redbay ambrosia beetle, Xyleborus glabratus, is an exotic wood-boring pest first detected in 2002 near Savannah, Georgia.  The beetle’s dominant fungal symbiont, Raffaelea lauricola, is the pathogen that causes laurel wilt, a lethal disease of trees in the family Lauraceae. Redbay ambrosia beetle and laurel wilt have since spread to seven states in the southeastern U.S., resulting in high mortality of native Persea species, including redbay (P. borbonia), swampbay (P. palustris), and silkbay (P. humilis).  Laurel wilt now threatens commercial avocado (P. americana) in south Florida, but in contrast to the situation in forests, X. glabratus is detected at very low levels in affected groves.  There is evidence that avocado is a poor reproductive host for X. glabratus, and that other species of ambrosia beetle may acquire R. lauricola and potentially function as secondary vectors.  To better understand the beetle communities in different ecosystems exhibiting laurel wilt, parallel field tests were conducted in an avocado grove in Miami-Dade County and a swampbay forest in Highlands County, FL.  Both sites contained a mixture of healthy trees and trees symptomatic for various stages of laurel wilt.  Treatments included ethanol lures (the best general attractant for ambrosia beetles) and essential oil lures (the best attractants for X. glabratus).  This presentation summarizes the numbers and diversity of ambrosia beetles captured in field tests, as well as data on the species which could reproduce successfully on host material collected from the two sites.