Control of the Emerald Ash Borer May be on the Horizon at Last

I want to front load this information. If you have on your property, or know the location of healthy Ash trees there will be contact information at the end of the article. Report healthy trees. There are two ways that the battle to save America's ash trees is being fought. Cultivating resistant trees is one way. You can be part of the team that fights to control the Emerald Ash Borer by simply helping to locate trees which may have a degree of immunity. Scientists are working on a second front.

I used to build boats. For each one I built, I'd make four sets of oars, each oar ten foot long. My friend Todd Pascarella makes baseball bats in Fleischmanns for his team. For both of us the wood of choice is ash. For a hungry little beetle which came across the sea, most likely in the wood of shipping pallets around 1990, the food of choice is ash.

According to Jason Denham, Supervising Forester, Bureau of Invasive Species & Ecosystem Health, New York State Department of Environment Conservation, we in the Catskills live at ground zero, where the Emerald Ash Borer (EAB) began to destroy our nation's ash forests.

The limited use of insecticides has been a failure, with ash trees quickly falling victim to the EAB from one end of the continent to the other. Use of the poisons, emamectin benzoate, imidacloprid, dinotefuran, and azadirachtin cannot be a solution employed on a large scale, due to the danger of unintended fatal consequences to the pollinator community, which is presently under serious threat in the United States. The conditions under which insecticides can be absorbed and useful to trees are also limited in ways by which the infestations are not hampered.  

Jian J. Duan is a hero in this story. He traveled to the Russian Far East to Primorsky Krai to discover how ash thrives in an environment where the EAB lives and burrows into ash trees. He and his team found that there exist tiny wasps as small as pinheads, whose larva feeds on the larva of EAB. There are several species of these wasps, and the next important step in the fight to control this infestation, was to insure the wasps that were to be introduced to the fight, would not themselves set off an imbalance by feeding on anything our forests need.

I am greatly simplifying this story, My graduate studies are law and politics. My cousin, Eva Otway, however, studied bugs. So, for Eva, I will add the following from an abstract of a paper Jian and others in his field authored. He points out that three other wasps which feed on EAB were collected in China. "Shortly after the detection of EAB in North America, a classical biological control program was initiated by the U.S. Department of Agriculture against this invasive wood-boring beetle (Bauer et al., 2008). This program led to the introduction of three species of hymenopteran parasitoids from northeast China in 2007 and one additional species from the Russian Far East in 2015 (Register, 2007, Federal Register, 2015). The three biocontrol agents from China included the egg parasitoid Oobius agrili Zhang and Huang (Encyrtidae) and two larval parasitoids Tetrastichus planipennisi Yang (Eulophidae) and Spathius agrili Yang (Braconidae). The introduced agent from the Russian Far East is Spathius galinae Belokobylskij & Strazanac (Hymenoptera: Braconidae)." (Field parasitism and host specificity of Oobius primorskyensis (Hymenoptera: Encyrtidae), an egg parasitoid of the emerald ash borer (Coleoptera: Buprestidae) in the Russian Far EastJian J. Duan a,Jonathan M. Schmudea, Kristi M. Larson a, Roger W. Fuester a, Juli R. Gould b, Michael D. Ulyshen c)

A female Spathius Galinae or Spathius Agrili wasp feels the EAB larva drilling in the tree, through the bark with her sensitive feet. The wasps then drill down through the bark to the larva and then they lay their eggs in the beetle larva. By so doing, their larva consumes enough EAB larvae for the infected tree to survive.

What was needed, and what has stepped up to the challenge was a partnership between the Federal, State and local agencies to introduce these little environmental warriors to our forests and to monitor their success. I am happy to report that the results have been hopeful at the very least.

As much as I'd like to say that one day our ash forests will again cover our mountains and stretch from one coast to the other, Forester, Jason Denham cautions that "biological control is a very slow and uncertain process." Nature's models are not simple and we can never predict all the variables which may arise over the next decades it will take for young trees to be cultivated, grow and spread.

When asked if he may predict when we may see a successful outcome of the program to control EAB, Jason replies with an example. Decades ago, in the 1930s, when the Spongy Moth was still called the "Gypsy" Moth, (On behalf of my Romani mother, thank you Jason for using the current name) a program was commenced to employ a fungus, Entomophaga maimaiga and a virus, Nucleopolyhedrosis Virus to control outbreaks of the Spongy Moth. They were at first considered a failed effort. However, today this method is still used "to end outbreak cycles in the North East today." The moth has not been eradicated, but rather today is controlled by creating a balance that is tolerated by the natural environment.

We can't predict how the natural environment may change or even how future decisions by human society may impact the future of American forests. (cue the song Big Yellow Taxi, by Joni Mitchel.) Progress towards a future with ash trees takes a partnership with scientists of many kinds, with government and with people willing to make keeping our native forests thriving a priority.  

Jason does say that there is evidence that the wasps have "been establishing themselves in New York, in multiple locations." This means that they have been found to be present after three years, or a fourth generation is surviving to create next generations after the initial release. Should this continue they will become a natural part of the ecology here, and we may reach a balance between the destructive insect and the predator, all to the long term survival of the ash trees as host to both.

Besides EAB eating wasps, there is another front in this battle. Each of us should look for "lingering ash." If found, report them to MaMA.  Readers may find out how to do this through the MaMA webpage. The webpage titled "Monitoring and Managing Ash (MaMA) A citizen-science-driven program for conservation and mitigation," (https://www.monitoringash.org/) defines what they need to find as,"Lingering ash are those mature, native, untreated ash trees that persist in healthy condition significantly after the vast majority of mature, native, untreated ash in the same area have been killed by EAB. Research led by the USDA U.S. Forest Service has shown that selective breeding of ash trees derived from scion (twig samples) taken from lingering ash can yield highly EAB-resistant trees within two generations, offering tremendous hope for ash conservation. A compelling presentation on this project can be seen here."

It is important to go to the MaMA website. It offers hope and a strategy to help us to earn that hope. As the website states "The MaMA framework replaces the progression of hopelessness that typically characterizes EAB invasion with particular, constructive actions appropriate to each stage of EAB infestation:"

I'd like to close with thanks to Dana Ferine and Jason Denham for their time pointing me in the right direction and to absolve them of any blame in technical errors made by my lack of understanding of the materials presented.