Cities may help spotted lanternflies spread faster

New genetic research suggests spotted lanternflies (Lycorma delicatula) may be winning their invasion partly because cities mirror the urban environments where the insects’ traits evolved. Scientists studying their DNA connect a chain of bottlenecks and toxin-

For years, spotted lanternflies have arrived in mid-Atlantic cities in eye-catching waves—polka-dotted wings, sudden swarms, and the kind of visibility that makes an invasion feel personal.

In the U.S., the insect is often described as a bigger economic threat in the countryside, especially for grapevines. But new research argues that the city story isn’t random. The way human-built landscapes reshape the world may be doing something more than providing a convenient ride—it may be selecting for traits that let these bugs take hold more easily in one urban place after another.

Kristin Winchell. an evolutionary ecologist at New York University. saw her own entry point into the question when the spotted lanternfly reached New York City in July 2020. She wanted to test a hypothesis with a long name—anthropogenically induced adaptation to invade. The idea is simple: cities. as extreme examples of landscapes humans have reshaped worldwide. can be ecologically more alike than natural ecosystems. In that case, a species adapted to local urban conditions might invade a different city with less friction.

The timing mattered for the broader detective work. In the U.S., spotted lanternflies were first detected about an hour’s drive from downtown Philadelphia in 2014. Since then. their spread has tracked a web of cities from Greensboro. N.C. to as far north as Boston and as far west as Detroit. with sightings scattered as far as Chicago. Cincinnati. Nashville and Atlanta.

To see whether urban success had a genetic basis. Winchell and her colleagues collected spotted lanternflies from across the invaded territory. along with samples from urban and rural locations in their native Shanghai. They then dug into the insects’ genes. Their results, published in the Proceedings of the Royal Society B, supported what researchers had suspected: the U.S. population of spotted lanternflies stems from a single introduction. That origin created a distinctive “bottleneck” in the species’ genetic diversity.

But the genetics didn’t stop there. The scientists also detected signatures of two previous bottlenecks in the population that went on to spread in the U.S.—one about a decade earlier. likely triggered by the lanternfly’s original invasion of South Korea. and another about 170 years ago. That older bottleneck coincided with Shanghai’s urbanization.

The researchers found something else that pointed toward an urban head start. They identified key genes related to toxins in modern Shanghai lanternflies collected in urban areas. but not in those from natural forests. The implication was stark: those genes might have helped the bugs develop a foothold in urban environments long before any arrived in the U.S.

Winchell put the city-route advantage into everyday terms. “The fact that they landed in the largest contiguous metropolitan region in the U.S. was probably really important to their rapid spread here,” she said. She explained that if you travel from Baltimore up to Boston by train. you pass through many places where you could hop off and still remain in cities. “It gives them a lot more opportunities to disperse into habitats that they are adapted to.”.

Other work suggests the invasion may be self-accelerating. Urban spotted lanternflies in the U.S. are growing larger than rural ones. which could allow them to travel farther thanks to relatively larger energy stores. produce more offspring—or better withstand hot temperatures. The implication, from that line of research, is that the evolution of the insect in cities may be continuing.

Those findings land with urgency in cities that already look conquered. Julie Urban. an evolutionary biologist at Pennsylvania State University who was not involved in the genetic analysis. said the spotted lanternfly’s story is a warning for biologists to pay attention to what’s happening in cities and other heavily human-shaped places before an invasion starts.

Urban studies plant hoppers, the broader group that includes spotted lanternflies. She is one of the few researchers in the U.S. who knew about these insects before they arrived. Her familiarity is built on more than professional curiosity—she has spent more than a decade watching plant hoppers surge into fame and spread into places they didn’t used to be.

In her telling, the sheer oddness of plant hoppers makes them easy to underestimate until they show up everywhere. She described more than 12. 000 described species worldwide. including insects that grow a cluster of tail-like wax spikes out their rear. and others with heads shaped like a cashew nut or a shrew’s long. button-tipped nose. She also pointed to a particularly unusual feature of the spotted lanternfly: she said females can rearrange their internal anatomy to pass their microbiome on to their eggs.

Urban compared the invisibility of many plant hoppers in the wild with what cities have become since the spotted lanternfly arrived. “In the wild, plant hoppers are usually hard to find,” she said. Even in hotspots, she noted, you might find only a few individuals of a few species. That scarcity doesn’t match the crowded reality of urban sightings. where adult lanternflies are unmissable once their numbers take off.

Her personal reaction carries its own weight. “It’s been very strange, but I think that’s why I feel a sense of obligation to help,” Urban said. “This is my first invasive.”

New York City offers a reminder that invasions don’t wait for the spotlight to arrive. A decade before New York City hosted spotted lanternflies in earnest, another invasive insect landed there. Nicknamed the ManhattAnt—eventually identified as the European Lasius emarginatus—the ant now lays claim to three in every four ant colonies in the city. according to Ellen van Wilgenburg. a behavioral ecologist at Fordham University.

The ManhattAnt’s success, van Wilgenburg said, depends on traits that fit city life. It moves fast, climbs high, and can tolerate hot city streets. Those advantages have helped it outcompete the city’s native ants without most residents noticing. “They don’t get any attention, because no one cares about ants,” she said. Even scientists. she added. are not keeping up—only a handful of papers examine the species. compared with dozens about spotted lanternflies in the U.S.

That imbalance is where the spotlight may turn into something useful. Winchell suggested the spotted lanternfly’s celebrity status could become a boon for understanding how invasions proceed over time—how they become endemic and how they interact with native environments.

“I think it could become a model system for really understanding how invasions proceed over time, how they become endemic and how they interact with the native environments,” she said.

For now, the evidence is pointing toward a hard lesson for urban ecology: cities may not just provide a pathway for newcomers. They may also offer the conditions—down to the genetic level—for an invasion to succeed faster than many expect.

spotted lanternfly Lycorma delicatula invasive species cities urban ecology anthropogenically induced adaptation genetic bottlenecks toxin genes Shanghai urbanization South Korea invasion Proceedings of the Royal Society B New York City ManhattAnt Lasius emarginatus