A tiny green insect is killing hundreds of millions of ash trees throughout the United States and Canada, and hordes of them are heading to Vassar. Biology prof. Margaret Ronsheim and biology major Tim Veit ’16 say they know they can’t stop the emerald ash borer from doing a lot of damage, but they’re devising a strategy to save a few of the ash trees on the campus.
Working under the auspices of the college’s Undergraduate Research Summer Institute URSI), Veit is deploying a wasp that has proven to be an effective predator of the ash borer. He is attaching small capsules containing pupae of the Oobius agrili wasp on the trunks of 12 ash trees. The wasps will hatch in late July, about the time the infestation is expected to arrive.
There are several hundred ash trees on the Vassar campus and Ecological Preserve, far too many to be able to save them all, Ronsheim says. One goal of the URSI project is to protect a dozen trees so seeds can be harvested and more trees can be planted after the infestation wanes, she says.
Veit, a pre-med major from Fairfield, CT, says he knew “virtually nothing” about the ash borer infestation before he began working on the project in June. He says it’s gratifying to be able to help some ash trees on the Vassar campus fight back. “I like being on the front lines in a real-life situation where what we do here can make a real difference,” he says.
Scientists believe the ash borer came to the United States in packing crates made of untreated wood that were used on ships delivering Asian goods to Michigan in 2001 or 2002. The infestation spread quickly, killing virtually all ash trees in the Detroit area. “Most ash trees in the state of Michigan are dead,” Ronsheim says. The infestation has already reached parts of Ulster County, just across the Hudson River from Poughkeepsie, and some of the insects have been spotted in northern Dutchess County, less than six miles away, Ronsheim says.
Ronsheim says saving at least some of the ash trees is vitally important. “If all them die, many species insects and other organisms that rely on the ash tree will die with them,” she says. “That would be a significant loss to the ecosystem.”
Losing all of the ash trees in the ecological preserve -- would be particularly devastating, Ronsheim says. “Ash trees provide more than 10 percent of the tree canopy for the preserve,” she explains. “Losing them would cause a ripple effect – it would spur growth of invasive vines that would choke other plants.”
Because Vassar is being pro-active, preparing to combat the infestation before it arrives, the federal government is interested in the outcome. The college is the first institution in the country to take remedial action before the ash borer actually arrives. If the measures being tested here are successful, Ronsheim says, they may be used elsewhere. “We’re working with the U.S. Department of Agriculture on this,” she says. “The government is helping us because we’re a little ahead of the curve, and the more trees we save, the more seeds we can preserve so we can do some planting when the infestation is over.”
Ronsheim and Veit credit another member of the biology faculty, lecturer and lab coordinator Mary Ellen Czesak, with devising an effective way to deploy the wasp pupae. Czesak places enough pupae to hatch about 100 Oobius agrili wasps in small plastic containers -- she’s dubbed them “oobinators” – that Veit can attach to the trunks of the trees.
Veit says he’s optimistic that deploying these oobinators will mitigate some of the damage to at least some of the ash trees on campus. “Using these wasps has a proven track record in Michigan, where the emerald ash borer originally appeared,” he says.
In addition to deploying the wasps, Veit is also injecting some trees with a substance called azadiracthin, derived from the Indian neem plant, which has been shown to discourage the ash borer from feeding.
He says he’s anxious to see how effective the URSI team’s fight against the emerald ash borer will be. “This infestation is a relatively new phenomenon – only about a decade old – so it’s exciting to be doing something that may have a real impact,” Veit says. “We’ve done the diagnosis and we have a prognosis, but we’re still unsure about the treatment. We don’t know the outcome, but it’s exciting to be part of this – to see science in action. If this works, we will save a lot of trees”
EAB images courtesy of bugwood.org