You can add one more pest to the ever-expanding list of insults to our native trees and forests.
A recent N.C. State University news release says imported ambrosia beetles have the potential to devastate tree crops in this country – particularly red bay, avocado, oaks and poplars.
The ambrosia beetle normally tunnels into the wood of dead trees. There it introduces a type of spore called a conidia, effectively seeding the tunnel with a fungus. The beetle farms this fungus as its food source.
Normally, this doesn’t create a problem since they are tunneling in dead wood. But imported beetles, perhaps brought in on shipping pallets or crates, are apparently confused when they encounter similar tree species in alien environments. They are using live trees to conduct their farming practices.
The infection triggers a tree’s immune system, which cuts off its water supply in an attempt to fight the fungus. The tree then dies of thirst.
“Only about 12 species of ambrosia beetle are creating problems so far, but there are thousands of other species in the world, many of which could be devastating to any number of tree species,” said Jiri Hulcr, a postdoctoral research associate at N.C. State and a lead author of a paper describing the research.
“Dutch elm disease is also caused by a fungus that is spread by beetles, and it ravaged the elm population in North America and Europe.”
The red bay ambrosia beetle from Southeast Asia was found in Bladen County in March. The beetle first turned up in Georgia in 2002 and has been spreading in the Southeast and along the Gulf coast.
The beetle introduces a fungus known as laurel wilt. The laurel family includes pondberry, pond spice, swamp bay, spicebush and sassafras. Mountain laurel is not included in this family. This beetle poses a significant threat to the avocado industry in Florida. The red bay is an important component of maritime forests.
Further study would indicate whether these beetles are the leading edge of a still-developing problem or if the worst damage has already been done.
The researchers say the insects pose enough of a worldwide threat to warrant study in a “global, biogeographically and phylogenetically explicit comparative framework.”
They cite the occurrence of ambrosia beetle species having affected oak trees in Japan, poplars in Argentina and Italy, and various other tree species in Korea, Israel, Thailand and the United States, from Ohio to Florida.
The beetles are typically spread through wood products such as crates or packing material and can be transported when moving dead wood from one area to another.
“Many of these species are transported in wooden shipping pallets that should be treated to kill insects but aren’t,” Hulcr said, adding that moving firewood contributes to the spread of these beetles.
The red bay joins a host of other trees threatened by the importation of alien insect pests and disease pathogens. These include the emerald ash borer in the north threatening ash trees, woolly adelgid preying on hemlock and fir species in the Southeast, thousand cankers decimating black walnuts and arriving from the west, and Asian longhorned beetles attacking maples in New York. And the list goes on.
Let’s hope these species don’t follow the Eastern elm and the American chestnut down the path to oblivion.
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