To most people, the buds and sprouts of April are welcome heralds of spring. But to some farmers and scientists in the southeastern corner of Pennsylvania, these signs mark the beginning of a long season of dread.
Their worry is Lycorma delicatula, the spotted lanternfly. It is an invasive pest with a voracious appetite and remarkable reproductive talents.
Native to Asia, lanternflies first appeared in Pennsylvania in 2014. Despite a quarantine effort, they have also been discovered in small numbers in New York, Delaware and Virginia.
In their native range, lanternflies feed primarily on one type of tree — Ailanthus, the tree of heaven. The trees are an invasive species, too, common across the continental United States, and so entomologists fear lanternflies one day may spread to far-flung corners of the country.
A nationwide outbreak would be something of a disaster, some scientists believe. Among the lanternfly’s more alarming qualities is an ability to feed on a huge range of plants, including many of commercial value.
Lanternflies are believed to use at least forty species of native plants in the United States as hosts. They are particularly fond of grapevines, apple and stone fruit trees as well as a number of hardwood trees, like black walnut and maple.
“We’ve seen it in hops, we’ve seen it in some of the grain crops that are out there, soybean and what have you,” said Fred R. Strathmeyer Jr., Pennsylvania’s deputy secretary of agriculture. “It’s able to feed on many, many different things.”
While it is too soon to gauge how much damage lanternflies might cause in the long-term, they can easily decimate certain crops in a single season.
“They’ve been appearing in grapes, and we have reports from growers last year of a 90 percent loss,” said Julie Urban, a senior research associate at Penn State.
Then there is the lanternfly’s unusual ability to lay eggs on almost any surface. While other species tend to deposit eggs on a living plant or in soil nearby, lanternflies can place a bundle of eggs nearly anywhere — wheel wells, train cars, shipping containers.
Agricultural inspectors in Pennsylvania have even started checking beehives for lanternfly eggs.
“Most pests deposit their eggs on their host plant, or very close, so they already have food available,” said Surendra Dara, an adviser at the University of California Cooperative Extension.
“Those that have the advantage of being able to lay eggs on non-plant material obviously have a better chance of surviving and spreading,” he added.
To try to contain lanternflies, regulators have set up a quarantine zone in Pennsylvania that now spans over 3,000 square miles (up from 174 in 2016) and includes 13 counties, as well as Philadelphia.
The state prohibits the moving of certain items within the zone, including firewood, outdoor furniture and construction debris. Officials also have launched a permit program for companies shipping goods out of the area.
“It’s not just an agriculture problem, this is truly an across-the-board commerce problem, because we are trying not to move it,” said Mr. Strathmeyer. “This is everyday people, this is the trucking company, the U.P.S. driver, the delivery guy.”
In February, the federal Agriculture Department stepped in as well, setting aside $17.5 million in emergency funding to finance research and help the quarantine effort.
Many scientists who have studied lanternflies fear that the pace at which populations have grown so far suggests an uphill battle ahead.
“It’s unbelievably eruptive in terms of its population,” said Michael Saunders, a professor emeritus of entomology at Penn State. “The very first year we went out, in 2015, you had to really hunt for egg masses, and then over the next two years it was just spectacularly exponential in its growth.”
“I’ve been through a few waves of invasive species, and this is far and away the most incredible thing I’ve ever seen,” he said.
South Korea is the only other country in which the spotted lanternfly is an introduced pest. It was first observed in 2004, and its impact on agriculture there has become a cautionary tale.
“It spread across the whole country in three years,” said Dr. Urban. “It’s still a problem there.”
Like aphids, lanternflies feed on plant sap and excrete most of the carbohydrates they consume in the form of honeydew — a sticky, syrupy liquid. The honeydew promotes the growth of mold, which can ruin produce and cover leaves, blocking out sunlight and killing plants.
In residential areas, honeydew can coat yards and porches, and its sugary consistency attracts gnats, bees and other unwanted insects.
“I’ve actually seen stalagmites of hardened honeydew on the ground,” said Dr. Saunders. “If you’re an entomologist, it’s spectacular, but if you’re a homeowner and you have these in your yard, it’s a nightmare.”
Lanternflies have mostly been contained in Pennsylvania so far, so some experts hope that they may still be eradicated through traditional means.
A variety of insecticides are being tested. In March, lawmakers in Maryland even tabled a bill to ban chlorpyrifos, a pesticide deemed unsafe by the Environmental Protection Agency some years ago, in anticipation of needing it to combat lanternflies in coming months.
Researchers have also begun studying the insect’s natural predators in Asia, with an eye to possibly releasing them in the United States. Several species of parasitic wasps are under consideration as a method of biological control, though this strategy typically only becomes practical once an invasive species becomes established.
“Biocontrol is an option that you would take up after eradication has been ruled out,” said Kim Hoelmer, a research entomologist at the Agriculture Department.
Scientists are pondering more experimental solutions as well.
A team of researchers at the University of Kentucky is exploring using RNA interference, or RNAi, to develop a novel insecticide. The technology works by silencing the expression of genes that are critical for vital functions like movement, but are also unique to a given species of insect.
Last year, the E.P.A. approved the first RNAi-based insecticides for use against another pest, corn rootworm.
“RNAi is one of the ways to control insects in a target-specific manner with precision, without harming the environment,” said Subba Reddy Palli, a professor of entomology at the University of Kentucky.
While RNAi has proved ineffective against other types of insects, notably many species of butterflies and moths, early indications are that the spotted lanternfly may be susceptible.
With more sophisticated solutions still years away, however, many of those working to halt the advance of lanternflies in the field are staying focused on the present.
If trends continue, this season is expected to be an important predictor of how severe the problem could become.
“2018 is going to be a critical year for us to know whether we’ll be able to really effectively contain, suppress and ultimately eradicate this pest or not,” said Osama El-Lissy, a deputy administrator of plant protection and quarantine at the Agriculture Department.
“It is pivotal, this spring.”
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