American sweetgum tree

UF Scientists Prepare for Devastating Pest in China Before it Makes its Way to U.S.

Dan Forestry, Industry News Release

American sweetgum tree

The foliage of a sweetgum tree. Trees, leaves, fall, cellulosic ethanol production.
(UF/IFAS Photo by Tyler Jones.)

A previously unrecognized pest is making a name for itself devastating American sweetgum trees in China. Now, University of Florida researchers fear the insect will make its way to the United States and devastate its sweetgum trees.

The bug was so obscure it recently had no scientific name until researchers realized it was responsible for the death of thousands of American sweetgum in China. China has its own native species of sweetgum but began importing and cultivating American sweetgum as an exotic ornamental plant. It is prized for its colorful autumn foliage.

Unfortunately, it is not only landscape artists who find the tree attractive.

A Chinese bark beetle called the “sweetgum inscriber” is wreaking havoc on the trees, according to UF Institute of Food and Agricultural Sciences researchers. The beetles use pheromones to call other beetles to swarm a tree, said Jiri Hulcr, a UF/IFAS School of Forest Resources and Conservation assistant professor. The tree inevitably exhausts its resources trying to bar the pests from boring into its bark and dies. The pest has a 100 percent lethality rate.

“Our colleagues in Shanghai discovered if they put up American sweetgum, they get hammered,” Hulcr said. “Thousands and thousands of dead sweetgum.”

The team is concerned trade between the U.S. and China means the pest will make its way to the U.S. where it could devastate sweetgum populations.

Sweetgum contributes 11 percent of the hardwood timber volume in the South. An infestation could mean a loss of $4.6 million each year for growers, according to UF/IFAS assistant research scientist Andres Susaeta.

The tree is also a significant feature of urban forests, where it provides ecological, social and economic benefits to around 80 percent of the U.S. population, Susaeta said.

“We want to be ready before it shows up,” Hulcr said, “which is in line with our whole philosophy of proactive management of emerging threats to forests.”

UF/IFAS researchers are working to learn all they can about the sweetgum inscriber to prepare authorities to take action should it arrive in the U.S.

“We’re doing two things: estimating the potential damages that the beetles can do if it was to be introduced to the United States, and studying its biology more in China so that we can potentially have some kinds of ideas about management in case it shows up,” Hulcr said.

The team is investigating whether the pest is limited by climate, and what natural enemies it may have, among other questions, Hulcr said.

The likelihood of the pest entering the U.S. is very low, Hulcr said. However, we are not willing to take any chances, he said.

by Beverly James, University of Florida Institute of Food and Agricultural Sciences

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