USDA-ARS Strategies to Address the Imminent Threat of Redbay Ambrosia Beetle and Laurel Wilt Disease to Florida Avocados

The Avocado Industries in the U.S. and Mexico – as well as the USDA avocado germplasm collection in Miami – are in danger of collapse due to laurel wilt. This deadly disease of avocado and other trees in the Laurel family (Lauraceae) is caused by a mycopathogen (Raffaelea lauricola) vectored by an exotic wood-boring insect, the redbay ambrosia beetle (Xyleborus glabratus Eichhoff). Impact of this pathogen/pest complex is potentially devastating. Once infected with Raffaelea, tree mortality can occur in as little as 6 weeks. First detected in the U.S. near Savannah, GA in 2002, the beetle and its obligate fungal symbiont have spread along the coast into South Carolina and Florida. Recently, laurel wilt has been confirmed in Martin County, ~70 miles north of Florida’s commercial avocado groves, estimated to be worth about $13 million annually. Xyleborus glabratus (Curculionidae: Scolytinae) is a cylindrical beetle about 2 mm long. Males are flightless and remain within the host tree. Mated females disperse and bore into new hosts, forming galleries where eggs are laid. The galleries are inoculated with Raffaelea spores (carried in mandibular mycangia), and the fungal growth (“ambrosia”) provides food for larvae and adults. The fungus continues to spread throughout the host’s vascular system, blocking water transport