The emerald ash borer is an invasive species of beetle that originated in Asia and was introduced to North America in 2002. In the time since, the beetle species has killed hundreds of millions of ash trees throughout the continent. Some researchers believe the emerald ash borer could eliminate the ash tree species.
Ash trees are greatly valued due to their strength and durability. These properties make the wood of the ash tree an important component in common items like tool handles and baseball bats. Many hunters also prefer bows made from ash wood due to the wood’s elasticity.
These trees also play a major part in the environment. For instance, their leaves and seeds provide nutrients to butterflies and caterpillars. So, the immense reduction of the ash tree population in North America could lead to harmful economic and ecological impacts.
How Do You Stop them?
Researchers, scientists, and foresters often resort to costly methods of chemical treatment to eradicate invasive species. However, the use of chemicals can harm other trees and introduce toxins into the environment that result in further ecological damage.
Biological control, or biocontrol, may lead to a more effective pursuit of removal. This process involves using native predators to feed on the emerald ash borer, thus reducing its growth and hopefully lowering the overall population of the invasive species. So far, researchers have found potential success in two groups of native predators.
Bark Foraging Birds
Woodpeckers, nuthatches, and other bark-foraging birds are often abundant in areas near the spread of the emerald ash borers. These birds pick at the bark of a tree to dislodge one of their preferred food sources: burrowing insects.
In small sample sizes, researchers found that bark-foraging birds through two response mechanisms: a functional response and a numerical one. With a functional response, woodpeckers and nuthatches change their own behavior to target the invasive species. That is, they’ve adapted to the emerald ash borer by realizing its potential as a new source of food. In fact, an extremely localized study found that in an area decimated by ash borers, woodpeckers were able to eat 85% of the invasive beetles in an infected tree.
The numerical response finds that as the population of the emerald ash borer grows, so does the population of its new predator. This match in growth can help bend the curve of the accelerated spread of emerald ash borers.
Neither response will save a tree once it’s been infected by the beetle. However, it can help mitigate its spread to a more manageable size.
Wasps
A group of four stingless wasp species may also help drive down the emerald ash borer population. Each of these wasp species is small, with the largest reaching the size of a mosquito. A benefit of these species is they are not attracted to humans or other animals, so they are not likely to cause harm to other animal populations in the area.
These wasps all attack emerald ash borers in similar, though slightly different ways. Generally, each makes its presence felt by injecting wasp eggs or larva near or next to the eggs or larva of the invasive beetle. As the wasps develop, they kill and feast on the eggs and larva of the emerald ash borer.
While these wasps won’t destroy the population of the invasive species by themselves, a recent study did show that they were killing between 20% and 80% of emerald ash borers in infected trees. As this lowers the reproduction rate of the emerald ash borer, these wasps have helped trees and forests begin to recover.
Contact Martin’s Tree Service Today
Caring for and maintaining your trees is of the utmost importance to your landscape, your property, and the surrounding environment. If you believe the ash trees on your property are showing signs of an emerald ash borer infection, reach out to us immediately so we can discuss treatment options.
Steve Martin
