Blue Ridge Naturalist: Here We Go Again— Emerald Ash Borer

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The United States Department of Agriculture started putting up purple boxes throughout Virginia in 2012 to detect the arrival of Emerald Ash Borers, a nonnative insect. These nondiscriminatory sticky boxes needlessly kill hundreds of innocent insects, including butterflies. Photo: Marlene A. Condon.

The Emerald Ash Borer, an Asian insect that was probably brought into the United States via cargo ships and airplanes carrying solid wood packing material, was first discovered in the Detroit area in 2002. From its initial occurrence, it has moved outward to 31 states and is expected to continue spreading throughout the country.

The adult beetle feeds on the foliage of an ash tree without causing any real harm. However, the immature beetle feeds on the inner bark where water and nutrients are transported throughout the tree. If there is an abundance of these larvae, they can kill the tree by interfering with its ability to get these essential liquids where they need to be.

The United States Depart-ment of Agriculture (USDA) has reported that the Emerald Ash Borer has killed hundreds of millions of ash trees in North America. Needless to say, and as is typical when a new foreign animal is found within the country, there is widespread panic. Municipalities, property owners, forest-products industries, and nursery operators are concerned about losing their ash trees.

In the beginning, the USDA behaved rationally, restricting and enforcing quarantines to prevent ash logs and firewood from potentially carrying Emerald Ash Borers into new areas. But as the insect’s spread continued unabated, the agency moved to pesticide usage.

Humans have become so used to the idea of employing poisons throughout the landscape that hardly anyone gives it much thought. Yet the consequences are profound.

A catastrophic result of treating trees with an injected pesticide (the main method of treating ash trees against the Emerald Ash Borer and hemlock trees for the Woolly Adelgid) is that those trees themselves become killing agents of non-targeted species as well as the targeted one. In these times of environmental consciousness, everyone knows that the wanton extermination of non-targeted species is an unsound practice.

Strangely, some environmentalists argue that we cannot afford to lose our native ash trees because they support native insects. However, there is no ecological value to keeping alive a poisoned ash tree that will attract and then snuff the life out of such critters as the caterpillars of Tiger Swallowtail and Hickory Hairstreak butterflies, among many others.

Imidacloprid, one of the commonly used pesticides suggested for use on ash trees, is already implicated in the decline of honeybees, and kills all kinds of insects and other kinds of invertebrates by interfering with the transmission of nerve impulses.

Proponents for the use of this pesticide always point to its safeness for use around people and their pets. But people and their pets are not the organisms that make the environment habitable for the rest of life on Earth, and therefore should not be seen as the only determinant for whether a pesticide is acceptably safe.

Although humans and pets would not, presumably, have much opportunity to eat this pesticide, the probability for other mammals, as well as birds, reptiles, and amphibians, is much higher. Employed systemically (injected into the tree), Imidiclopid moves easily throughout the entire plant, filling roots, leaves, pollen, nectar, and fruit with this toxic substance.

What this means is that any kind of animal making use of any part of a treated tree is susceptible to serious poisoning, whether it is a White-footed Mouse eating an ash seed or a Yellow-bellied Sapsucker getting sap. Does this matter? It certainly does when you consider that both of these species eat Gypsy Moths (an alien species brought to this country deliberately) and thus help to limit their numbers.

Although the United States government has spent millions of dollars trying to eradicate the Gypsy Moth from our forests via the use of pesticides, it is a battle that can never be won because pesticides simply breed resistance into the species, making it more of a problem for humans to deal with. 

It would be far more sensible to preserve ash seeds that could be planted after the borer populations have plummeted. Once large ash trees have been greatly reduced in number, the borers will starve for lack of a food source. A natural buildup of predator populations will take place and that will work to keep borer populations in check.

This scenario has already played out with the Brown Marmorated Stink Bug. Although populations of this nonnative insect (first detected in the US in 1998) were still noticeable in Virginia in 2017, its numbers were substantially reduced from previous years.

You might question my assessment, because for most folks, finding several dozen of these stink bugs around the house still counts as too many. However, just a few years ago there would be hundreds of them in the fall on house siding. In Shenandoah National Park, we couldn’t even exit the car because stink bugs were flying and landing everywhere! It was quite a phenomenon.  

Although my initial assessment of the population decrease was based upon what was happening in my yard throughout the 2017 growing season, I confirmed from bird-sighting and hawk-watch reports throughout the fall season that the population drop had occurred throughout the state. The complaints of stink bugs were very few and far between as compared to previous years! Lastly, a sure sign that numbers were way down was the absence of stink bug media coverage.

It’s strange that when some kinds of critters become problematic, the common and hysterical reaction of folks is, “We’ve got to do something!”, even if that “something” is to employ poisons that are harsh in their effect and non-selective in their action. No one considers that this demand for pesticides demands cruelty from researchers.

All pesticides are tested for toxicity by feeding them to animals and applying these substances directly onto their skin and/or into their eyes. Should people worry more about trees than about the inhumane treatment of animals, such as the bunnies and guinea pigs used in Imidacloprid testing?

If people would open their eyes to the big picture and learn more about all of the unseen but very real impacts of using pesticides, the world would be a much better place for us and the creatures that share it. Animals would no longer be subjected to immense physiological and psychological pain and suffering to test poisons, and our tax burden would be less because we wouldn’t be forced to support pesticide research and applications.

No species of organism has ever been eliminated by pesticides. Please reconsider your options the next time you think pesticides will solve your problems. 

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