Community of Bark and Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae and Platypodinae) in Agricultural and Forest Ecosystems with Laurel Wilt

SIMPLE SUMMARY: Redbay ambrosia beetle (RAB), a wood-borer native to Southeast Asia, was first detected in North America in 2002 in Georgia, USA. The beetle carries a fungal symbiont that causes laurel wilt, a lethal disease of trees in the family Lauraceae. RAB is now established in 12 southeastern states where laurel wilt has caused widespread mortality of native forest trees, including redbay, swampbay, and silkbay. In Florida, laurel wilt also impacts avocado, but in contrast to the situation in forests, RAB is detected at very low levels in affected groves. Other species of ambrosia beetle have now acquired the fungal pathogen and contribute to the spread of laurel wilt. To better understand the beetle communities in different ecosystems exhibiting laurel wilt, parallel trapping tests were conducted in an avocado grove and a swampbay forest in Florida. Traps were baited with ethanol lures (the best general attractant for ambrosia beetles), essential oil lures (the best attractants for RAB), and combinations of these lures, resulting in captures of 20 species. This study (1) documents differences in beetle diversity and population levels at the two sites, and (2) identifies the best lures or lure combinations for detection of different beetle species. ABSTRACT: Redbay ambrosia beetle, Xyleborus glabratus, is an invasive wood-boring pest first detected in the USA in 2002 in Georgia. The beetle’s dominant fungal symbiont, Harringtonia lauricola, causes laurel wilt, a lethal disease of trees in the Lauraceae. Over the past 20 years, X. glabratus and laurel wilt have spread to twelve southeastern states, resulting in high mortality of native Persea species, including redbay (P. borbonia), swampbay (P. palustris), and silkbay (P. humilis). Laurel wilt also threatens 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. Moreover, other species of ambrosia beetle have acquired H. lauricola and now 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. Sampling utilized ethanol lures (the best general attractant for ambrosia beetles) and essential oil lures (the best attractants for X. glabratus), alone and in combination, resulting in detection of 20 species. This study documents host-related differences in beetle diversity and population levels, and species-specific differences in chemical ecology, as reflected in efficacy of lures and lure combinations.