An Agricultural Research Service (ARS) researcher has developed a new tool to help Florida avocado producers concerned about a disease that is killing their trees. It's a lure that makes it easier to detect and control the invasive pest that spreads the disease.
Laurel wilt disease is spread by the redbay ambrosia beetle (RAB), which bores into the tree, deposits a fungus (Raffaelea lauricola), and triggers a defensive response that blocks the flow of water to the upper tree and limbs. Once infected, a tree can wilt and die within two months.
The Florida Department of Agriculture monitors for RAB with traps containing cubeb oil lures. But ARS entomologist Paul Kendra and his partners at Synergy Semiochemicals Corp. have developed an improved lure that emits higher levels of a key attractant. The compound, known as a-copaene, is found in the wood of avocado and other laurel trees. Kendra is based at the ARS Subtropical Horticulture Research Station in Miami, Florida.
The efforts have implications far beyond Florida's $23-million avocado industry. The disease was first detected in Miami-Dade County groves in 2012 and has since spread to nine other southeastern states. It could wipe out the $468-million avocado crop in California and the $1.2-billion avocado industry in Mexico if left unchecked.
Kendra and his colleagues distilled cubeb oil, separating out its chemical compounds for analysis, and exposed RAB to some of the most promising compounds to determine which ones were the most attractive. Based on study results, they developed two prototype lures and compared how well the two prototypes and the current cubeb lure attracted RABs during a three-month field trial.
The experimental lure with 50-percent a-copaene captured two to three times more beetles and could detect beetles even when they were in low numbers in avocado groves. The "high octane" lure also attracted RABs during the entire three-month trial. Synergy Semiochemicals, based in British Columbia, Canada, is now producing the lure for forestry and agricultural use.
Read more about this research in the November 2016 AgResearch.