An invasive insect has laid waste to an estimated 100 million ash trees across the U.S. Now Oregon foresters are taking pre-emptive steps to limit the bug’s impact.
The emerald ash borer is a metallic green beetle, and its larvae are destructive to ash trees. Upon hatching, they burrow through a tree’s cambium, essentially depriving it of nutrients and killing it.
Full body view of the emerald ash borer adult from above.
U.S. Geological Survey
Wyatt Williams is an invasive species specialist with the Oregon Department of Forestry. He says through a federal grant, crews are collecting ash tree seeds to preserve its genes.
“We can go anywhere in the state right now and collect seeds,” Williams told KLCC. “We have no restrictions. We don’t have any mortality from emerald ash borer. Our goal is to collect one million seeds from 30 populations across the state.”
Seeds will be stored at the Dorena Genetic Resource Center in Cottage Grove, and the USDA Seed Lab in Ft. Collins Colorado.
In a press release, the ODF quotes Richard Sniezko, Ph.D., stating that some seeds will be put in long-term storage while others will go to field research sites in the Midwest already infested with the emerald ash borer. Researchers in those affected areas will plant Oregon ash to see if any of the seedlings show natural resistance to the pest. If so, Sniezko said seeds from those same batches could be sown, with the resulting seedlings used to restore natural areas.
“The hope is that we might be able to have some resistant trees already growing in the landscape by the time emerald ash borer gets to Oregon,” said Sniezko.
In another scenario, if emerald ash borer wipes out Oregon ash and is then successfully controlled, the stored seeds could be used to reintroduce Oregon ash in the places it once grew. Or if the pest becomes entrenched, crosses could be made with the few resistant trees to build genetically diverse stocks of resistant trees.
“Since resistance is likely to be quite rare. there is a real danger that those few surviving trees won’t have the full range of genes a species has built up over hundreds of thousands or millions of years,” said Sniezko. “This effort is insurance against that kind of genetic loss.”
First detected in 2002 near Detroit, Michigan, the emerald ash borer has spread across the U.S., including the Colorado Rockies.
The emerald ash borer has yet to appear in Oregon, but once it does, the invasive beetle’s expected to cause great devastation to the state’s ash trees.
Williams says the insect is a formidable threat to forests, as the loss of trees would cause erosion, and make areas more prone to flooding.
“Emerald ash borer does not have any known native predators that keep the population in check,” added Williams. “That’s one of the reasons why we think it just runs rampant in the eastern United States.
“However, there’ve been about three or four introduced biological control agents. These are highly specialized parasitoids – mostly wasps but there are some flies - that only attack emerald ash borer at the rate of about 30% mortality. But that is not enough to slow down the expansion.”
The emerald ash borer is believed to have stowed away in wood shipments from Asia. Within the U.S., the bugs are believed to have spread inside firewood. It’s been found in roughly three dozen states.
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