Emerald Ash Borer May Become a Problem for Olive Growers

In October 2014, researchers at Wright State University discovered that an invasive insect called the emerald ash borer (EAB) was attacking white fringetrees (Chionanthus virginicus) in addition to ash trees. This was big news at the time. The EAB had already killed tens of millions of ash trees, and the fact that it could harm another species made it even more devastating.

Now the same researchers have found that the EAB can also successfully complete development on olive trees. Professor Don Cipollini has found that the invasive green beetle can feed and successfully develop into adulthood on stems of the Manzanilla olive tree, a Spanish variety that yields green table olives and is grown widely around the world.

“We are showing in this experiment that emerald ash borer indeed can complete development on olive,” said Cipollini. “It would add a potential pest to the olive cultivation industry. If we see this happening in nature, it could be a huge deal.”

Native to Asia, emerald ash borer was first found in the United States near Detroit in 2002. It is believed to have been in ash wood used to stabilize crates during shipping and may have arrived without notice a decade earlier. It is estimated that the borer will have caused $10 billion (AU$13.14 billion) in economic damage by 2019.

The borers attack trees by laying their eggs on the bark. The serpentine feeding galleries of the larvae inside the bark disrupt the flow of nutrients and water and starve the tree.

Cipollini acquired a stem of the Manzanilla olive tree from collaborators in California and inoculated it with emerald ash borer eggs. Eggs were placed on the stem in February, and the larvae were allowed to feed on it for about two months. Beginning in April, Cipollini and Donnie Peterson, an environmental sciences Ph.D. student from Black River Falls, Wisconsin, exposed them to cooler temperatures for two months to simulate winter in order to facilitate their development. More