“There are at least a billion ash trees in Minnesota. We have to use everything we can to stop this insect.”
With those words, Robert Blanchette lays bare the magnitude of the task before our state if we are to control the emerald ash borer.
A professor in the Department of Plant Pathology and researcher in the Minnesota Invasive Terrestrial Plants and Pests Center, Blanchette, along with his research team, is perfecting biological means to defeat this half-inch-long pest.
Life cycle of the emerald ash borer
- Female ash borers lay 40+ eggs in the bark of an ash tree.
- Eggs hatch in two weeks. Larvae emerge, then feed below the bark for 1–2 years, creating S-shaped “galleries”—this is the most destructive stage.
- Larvae then pupate, after which they turn into adults.
- Adults emerge through D-shaped holes in the bark.
- The adults mate, find another tree, and start the process over.
- The host tree will likely be dead in three to five years.
Marshaling microbes
The emerald ash borer, or EAB, can be stopped by removing ash trees from a vicinity in advance and planting other species. This method is costly in time, money and, often, emotions. Enlisting armies of biological agents to attack the insect will avoid these drawbacks.
But even if infestation and tree loss or removal looks inevitable, “We want to develop another tool for land managers to slow EAB down so they can have a smoother transition,” Blanchette says.
In Blanchette’s lab, graduate student Colin Peters researches fungi that infect insects. His work is geared to protecting black ash, a tree that forms an immense forest in northern Minnesota. The black ash is central to several Indigenous cultures, to whom it is important for making baskets or as a spiritual resource and source of medicine.
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