Attack of the Invaders: Using Exotic Wasps to Counter Emerald Ash Borers

The first wave of an invasion was observed in the Detroit area in 2002. Ash trees were dying everywhere in the region. The cause – a tiny metallic green beetle called the Emerald Ash Borer (abbreviated as EAB) which was likely introduced from Asia along with wooden shipping materials. By 2010, 20 million ash trees in southeastern Michigan, northern Ohio and Indiana were dead, with nearly 100% mortality. By that time, the infestation had spread to 13 states and two Canadian provinces, and the beetles continue to spread.

Ash trees make up about 12 percent of all forest land in Ohio, and are particularly abundant in swamp forests. The devastation was so heavy that one of the Toledo Metro Parks with a lot of ash was closed for an extended time while workers came in to cut down and burn the trees in a combined effort to protect the public from falling trees and to attempt to halt the spread of more beetles.

At OHS we became concerned about the potential affect of EAB at Cedar Bog Nature Preserve in Champaign County. Cedar Bog is a complex of various wetland habitats surrounded by drier buffer areas. The most critical habitats are the sedge meadows and their surrounding evergreen swamp forests composed of Northern White Cedar. However, a large area of the preserve is a hardwood swamp forest, where Black Ash, Green Ash, White Ash and Pumpkin Ash abound. In the wettest areas of the swamp forest, ash trees are as much as 60 to 80 percent of all the trees. Several uncommon or rare species thrive in the swamp forest, including the state endangered Small Purple Fringed Orchid (Plantanthera psycodes).

How do you protect ash trees from an exotic, invasive animal like the EAB? While there are chemical pesticides that are effective against the EAB, they are somewhat costly and impractical for anything beyond single, residential landscape trees. Further, the potential impact on other beetles and insects in a nature preserve quickly eliminated this type of approach at Cedar Bog. As early as 2003, researchers with the USDA started looking for natural predators of the EAB back in Asia where the EAB is native. They found three species of tiny, non-stinging wasps that are parasitic on the eggs and larvae of EAB. Experiments showed that they parasitize no other insects beyond the EAB, or if really stressed some other borers in the same genus as the EAB. After extensive studies to confirm their safety, the USDA approved them for release to help control EAB infestations. The staff at OHS put together a proposal to introduce these parasitic wasps at Cedar Bog and submitted it to the Ohio Department of Natural Resources for approval – a step required by Cedar Bog’s status as a Dedicated State Nature Preserve. The ODNR fully endorsed our plan, and commended us for taking a pro-active step to protect this unique nature preserve.

After several years of monitoring the site, in October of 2011 the first adult EAB showed up in the purple pheromone traps at Cedar Bog. Only two each of the EABs in each of two traps. In past wasp introductions, this would not have been sufficient evidence to start introducing the wasps – as the wasps are difficult and expensive to rear and the USDA wanted to make sure that releases took place at sites that had significant infestations of EAB. However, EAB may be established for a year or two already before they start showing signs of infestation, and many previous introductions were too little, too late. After several discussions, the staff at the USDA lab in Brighton, Michigan agreed that it was time to experiment with a more aggressive introduction of these parasitoid wasps. Yes!

On Friday, May 25, 2012 Dr. Avraham (Avi) Eitam of the USDA office in Reynoldsburg, Ohio brought out our first round of parasitoid wasps. Site manager Eric Doerzbacher and myself assisted him in locating the best spot for our introduction and then releasing the wasps. We selected a central point, and then divided the area around it into quadrants. Releases would take place on three ash trees in each of four adjacent quadrants to the central point. Since additional releases are planned, and monitoring of the effectiveness of the introduction is important, each tree used was marked with a numbered metal tag to assure our introductions and monitoring will be consistent.

A total of more than 4,000 parasitic wasps were released; 1877 of Spathius agrili (a parasite on larval EAB), 1088 Tetrastrichus planipennisi (another parasite on larvae) and 1452 Oobius agrili (a parasite on EAB eggs).

Some people have expressed concern over the introduction of wasps – might they not attack and sting visitors? The answer to that is a resounding “NO.” These wasps are very, very tiny – the largest (Spathius) measuring only about 5 mm long (about 3/16 inch).

The wasps were shipped by over-night delivery from Brighton, Michigan where they are reared to Dr. Eitam’s lab in Reynoldsburg inside of coolers. Friday, when Avi arrived with the coolers of wasps at Cedar Bog, we unpacked the small plastic containers which held the wasps – and proceeded to open each up on the specified trees. The two species of larval parasitic wasps were shipped as adults – so as we started releasing them, they flew and crawled not only on the ash trees, but also on our arms. It was sort of interesting, trying to ignore a few mosquitoes landing on us, so as not inadvertently swat one of these valuable wasps!

The egg-parasitic wasps (Oobius agrili) were shipped in the same plastic containers, but on eggs of EAB which they had already parasitized, and in which the wasp larvae were waiting to hatch and emerge. Instead of opening a container and letting the wasps fly away, these containers were tacked onto the trees upside down, with a layer of fine cloth netting sealing off the bottom. When the wasps emerge, they can easily crawl through the netting, and search the ash trees for more EAB eggs to parasitize.

There is no guarantee that the introduction of these three species of parasitic wasps will eliminate or even control the Emerald Ash Borers. That is certainly the hope – at least that they minimize the destruction of the ash trees and develop a balanced population of EAB and the parasites. That type of balance exists in many native wood boring insects and their parasites or predators. That is also the type of balance that exists now with other examples of biological control of pests, such as the weevil that feeds upon Purple Loosestrife which a couple of decades ago had taken over much of our Lake Erie marshes. Today, Purple Loosestrife has been greatly reduced by the weevils and is no longer a major threat to the marshes. So if this introduction of parasitoid wasps works, we might loose some ash trees, we will see some EAB surviving, but the parasitic wasps will keep the EAB from becoming so numerous that they wipe out all of our ash trees. All I can say is “Go wasps!”

Bob Glotzhober

Senior Curator, Natural History

RETRIEVING LOST STORIES – “USEFUL” OR NOT?

The Daily Beast, “a smart, speedy take on the news from around the world, combined with the depth and investigative power of Newsweek Magazine,” recently listed archaeology as one of the 13 “most useless” college majors.

I think the word “useless,” in this context, is unfortunate and wholly inappropriate. What the compilers of the list actually meant is that the job market for archaeologists isn’t exactly booming (true enough) and archaeologists, when we get jobs, don’t tend to make tons of money (also generally true). Does that really mean that archaeology is a “useless” college major?

In my latest column in the Columbus Dispatch, I responded to the Daily Beast’s bizarre characterization of archaeology as a “useless” major by focusing on the useful knowledge that it can provide. For example, by learning about the mistakes made by past civilizations, perhaps we can avoid repeating them.

Here I consider the less tangible rewards of majoring in archaeology.

Although I argue in my Dispatch column that archaeology could save the world -- or at least our civilization's precarious hold on it, I freely confess that I did not become an archaeologist to save the world. Nor did I choose this career because I thought I’d make buckets of money.

In fact, I chose to become an archaeologist because I was fascinated by the wonders of the past and the prospect of making new discoveries that would shed light on how we came to be what we are seemed to me to be a noble thing to which I could dedicate my life’s work. After thirty or so years of doing archaeology, I still believe I’m following a calling more than a career path.

In the course of my archaeological field school, I was the first person to put my hand in an 800-year-old handprint impressed in clay in the wall of a room in an Anasazi pueblo my team was excavating. I felt an electric connection with that long vanished person – as if our fingers actually had touched across the centuries. I feel something similar each time I lift an ancient stone tool or broken fragment of pottery from the earth. I am engaged in making connections with ancient people who have lost their voice and it is my privilege to bring their stories to life again.

The Princess of Pure Reason, in Norton Juster’s brilliant book The Phantom Tollbooth, tells the hero “whenever you learn something new, the whole world becomes that much richer.” (And she didn’t mean monetarily!)

I believe the world is richer for the retrieval of lost stories made possible by the science of archaeology. It’s sad that The Daily Beast, despite having all the “investigative power of Newsweek Magazine” at its disposal, doesn’t get that. I would bet that, unless archaeologists start getting better salaries, even if some of those stories lead to insights that end up saving the world, The Daily Beast still will be listing archaeology as a "useless major."

Don’t you believe it!

Brad Lepper

HENRY SHETRONE RECALLS THE EXCAVATION OF THE TREMPER CACHE OF EFFIGY PIPES

In the twilight of his career, Henry Shetrone, former Curator of Archaeology for the Ohio Historical Society and later its Director, reflected on "one-third of a century's inquiry into Ohio's prehistory." The manuscript, entitled Ohio Archaeology and Archaeologists, unfortunately was never published, but it is preserved in the archives of the Ohio Historical Society.

The following excerpts are from Shetrone's account of the excavation of the Tremper Mound where he "takes the liberty of reminiscing informally about ... an outstanding experience of which he was very much a part."

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It was the early summer of 1915... Shipment of camping equipment, tools and personal belongings by slow freight to the nearest railroad station; hiring a farmer to "haul" the outfit to the Tremper farm; setting up camp in a nearby grove; wives of the Curator and his assistant; a young surveyor and a college student, comprising the exploration party... Then followed the rainiest season on record for the locality... clothing, cots, shoes, everything damp and moldy for weeks, but spirits unflagging, sustained by pleasurable anticipations of things to come!

No time was lost in assembling a force of laborers and beginning exploration. ...

While some sort of "finds" were expected daily, three long weeks passed with nothing more than ... post-molds, stretches of carefully prepared floor, and two small deposits of cremated human remains, without artifacts! This, together with continuous rains and flooded trenches was not conducive to cheerful attitudes, either of the explorers or of the ladies back at camp, who struggled valiantly to keep the home fires burning and food prepared for weary workers...

Came a day when a workman called, "Hey, Boss, here's a lot of funny looking burnt stuff and stones." The author hurried to the spot with trowel and whisk broom, and in a few minutes uncovered a beautiful platform tobacco pipe, fashioned in the image of the quail -- Bob White! During the remainder of the afternoon several additional effigy pipes were removed, with still others in view. That evening, until after midnight, the assistant curator, the surveyor and the college student kept silent and awesome watch lest intruders disturb this ancient treasure. All of the next day was required to remove the more than 500 artifacts from the "cache," 136 of which were tobacco pipes.

The ceremonial or sacrificial offering occupied a space on the mound floor approximately six feet across... Most of the specimens had been intentionally broken... Fortunately, with few exceptions, all parts were recovered and afterwards restored by the museum technician. ...

The artistry displayed in fashioning these pipes is not surpassed in any prehistoric culture north of Mexico.

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The magnificent Tremper pipes can be viewed at the Ohio Historical Society's exhibit "Following in Ancient Footsteps."

AAA MAGAZINE "JOURNEYS" FEATURES ANCIENT OHIO TRAIL

The Cincinnati edition of the AAA travel magazine Journeys includes an article about Ohio's remarkable ancient earthworks!

Writer Sarah Jaquay features the Newark Earthworks, Fort Ancient, and Serpent Mound in her review of Ohio's "Sacred Grounds" in the May/June issue of this popular publication.

"The significance and allure of these sites is becoming apparent to visitors of all ages who want to know more about the ancient cultures that thrived here and built colossal architecture out of soil and stone, creating enourmous geometric figures, miles of paralell embankments, animal effigy mounds and hilltop enclosures."

Check it out!  And then take your own trip along the Ancient Ohio Trail.

ADENA EFFIGY PIPE INSPIRES ARTISTS

I recently received a package from Tracy Kessler and Charlotte Stiverson, teachers at the Columbus School for Girls, including letters written by the students who are working hard to have the Adena Effigy Pipe recognized as Ohio's official State Artifact. All of the letters expressed gratitude for their recent tour of the OHS archaeology exhibits and most listed the artifacts that had made the strongest impression on them. Not surprisingly, the Adena Effigy Pipe was mentioned most frequently and three of the letters included drawings of the pipe, which I am pleased to share.

The Adena Effigy Pipe is a powerful, iconic object and visitors to the exhibits frequently mention it as a highlight of the displays.

It would be hard to choose a more appropriate single object to represent Ohio's ancient American Indian cultures!

When the Cincinnati artist Charley Harper created a collage of the Ohio's Historical Society's archaeological masterpieces, he wisely placed the Adena Effigy Pipe at the center of the composition.

Come and visit the exhibit and experience the power of this remarkable sculpture for yourself!

And support House Bill 501 that would recognize it as Ohio's State Artifact!

Brad Lepper

ADENA EFFIGY PIPE MAY BECOME OHIO'S STATE ARTIFACT!

Last year, Charlotte Stiverson and Tracy Kessler, two teachers from the Columbus School for Girls, and their fourth grade classes began the process of having Ohio's General Assembly recognize the Adena Effigy Pipe as Ohio's official State Artifact. Their efforts are continuing this year -- aided by the students of the current fourth grade classes and the fifth grade teachers of Charlotte's and Tracy's former students!

Thanks to their efforts State Representatives John Carney and Mike Duffey are co-sponsoring House Bill 501 to add this magnificent sculpture of an ancient American Indian dancer to the list of iconic symbols that help to define our State!

It would hard to find a more appropriate artifact for this purpose!

The Adena Effigy Pipe is the oldest known rendering of a human in Ohio's corpus of indigenous art. And human effigies allow us to make an immediate and special connection with the people of the past.

It was found in the Adena Mound, which was located on the Chillicothe estate of Thomas Worthington, Ohio's sixth governor and one of its two first senators. The pipe has become a hallmark of the Adena culture (circa 800 B.C. - A.D. 100), which was named for the mound.

The Adena Effigy Pipe is one of the most famous artifacts in the collections of the Ohio Historical Society and is, perhaps, the artifact that is most often illustrated to represent the ancient American Indian cultures of eastern North America.

Listing the Adena Effigy Pipe as Ohio's State Artifacts would honor our indigenous heritage by giving a face to the too often forgotten American Indian people who were the first Ohioans.

Please contact your legislators if you agree that Ohio's ancient indigenous cultures should be honored by listing this wonderful effigy pipe as Ohio's Official Artifact!

For more information about the Adena Effigy Pipe, check out my article in the January/March 2012 issue of Timeline magazine: "The Adena Pipe: Icon of Ancient Ohio."

EXPLORE THE FORT HILL EARTHWORKS

The Arc of Applachia, in cooperation with Hopewell Culture National Historical Park and the Heartland Earthworks Conservancy, is offering a guided tour of the Fort Hill Earthworks.

Immerse yourself in the enigmatic constructions of the people known as the Hopewell Culture with two experts in interpretation and archaeology. Join ranger Bruce Lombardo for a guided hike to the ancient earthen enclosure at the top of Fort Hill, and then to the almost unknown Circle Mound, tucked away off one of the preserve’s hiking trails.

Following this will be a presentation on the numerous geometric enclosures of the Hopewell Culture found in southern Ohio by Dr. Jarrod Burks, a leading researcher on these structures.

The Fort Hill Eathworks site is not just a monumental hilltop enclosure listed on the National Register of Historic Places, it's also a National Natural Landmark!

When: Sunday May 20, 2012 -- 9:30 AM-4:00 PM

Cost: $15 per person -- lunch included.

Space is limited. Please visit the Arc of Applachia's website for more details and registration information:

Arc of Appalachia Fort Ancient Tour

Fort Hill is managed by the Arc of Appalachia on behalf of the Ohio Historical Society