One is the Deadliest Number

 

laurel_wilt_fungal_staining_AMayfield_Bugwood.jpgWhen the redbay ambrosia beetle, native to Asia, was first detected in coastal Georgia in 2002, it didn’t set off any alarm bells. All ambrosia beetles carry fungi that serve as a food source for adults and larvae living in tunnels under the bark of host trees and shrubs. Usually, these fungi aren’t harmful, but the Raffaelea lauricola fungus carried by the redbay ambrosia beetle is one major exception. It causes laurel wilt, a swift killer that has spread to nine states and killed as many as 300 million redbay trees since it was identified in 2004. But how did the epidemic start, and why does that matter so much now? Eastern Threat Center research ecologist Frank Koch is among university and Forest Service researchers who provide some hindsight in a study that was recently published in Biological Invasions. They hypothesized that the tiny beetle and its companion fungus began their rampage after a single introduction, likely near the Port of Savannah. Between 2000 and 2012, the researchers collected 14 female beetles in baited traps places in infested redbay stands in Florida, Georgia, Louisiana, and South Carolina. They also collected 57 fungal samples in these same states between 2004 and 2010. After extracting and sequencing DNA, they discovered that all the beetle samples were genetically the same, indicating they shared a common ancestor. Researchers also found that 95% of the fungal samples had identical genes, further supporting their hypothesis that a single introduction of a redbay ambrosia beetle carrying the R. lauricola fungus was all it took to set off the laurel wilt epidemic in the United States. Read more in CompassLive...

Pictured: A redbay stem shows vascular staining from R. lauricola. The fungus chokes off the movement of water within a tree, resulting in wilt and death within weeks or months. Photo by Bud Mayfield, U.S. Forest Service, Bugwood.org.

 

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