NEWARK, N.J. -- With winter's arrival comes the kind of news that may give New Yorkers the creeps. A species of cockroach never found in the United States before has been positively identified in Manhattan.
Unlike the roaches that New York residents have known and hated for years, this variety can survive not just indoors where it's warm, but also outdoors in freezing temperatures. The species Periplaneta japonica is well documented in Asia but was never confirmed in the United States until Rutgers insect biologists Jessica Ware and Dominic Evangelista documented its presence in a study just published by the Journal of Economic Entomology.
"About 20 years ago colleagues of ours in Japan reared nymphs of this species and measured their tolerance to being able to survive in snow," says Ware, who is an assistant professor of biological sciences at Rutgers-Newark. "As the species has invaded Korea and China, there has been some confirmation that it does very well in cold climates, so it is very conceivable that it could live outdoors during winter in New York. That is in addition to its being well suited to live indoors alongside the species that already are here."
The Asian species was first spotted in New York in 2012 by an exterminator working on the High Line, an elevated walkway and park on Manhattan's West Side. These cockroaches looked different to him from what usually crawls around New York, so he sent the carcasses to the University of Florida for analysis. The recipient, study co-author Lyle Buss, contacted the Smithsonian, which in turn brought in Ware because she had published several papers on cockroaches in the past. Evangelista, who is working toward a doctorate in Ware's lab, performed barcoding, an analysis of the species' genetic characteristics. That and other scientific methods he used confirmed what he and Ware suspected – the roach traps on the High Line had captured Periplaneta japonica.
How it arrived is not absolutely certain, but Ware and Evangelista suspect that one or more of the ornamental plants that adorn the High Line arrived in soil that contained the new pest. "Many nurseries in the United States have some native plants and some imported plants," Ware says, "so it's not a far stretch to picture that that is the source." Evangelista adds, "If we discover more populations in the U.S., we could trace their genes back to try to figure out their exact sources." But they agree that could be a very difficult detective job.
What New Yorkers probably really want to know isn't so much the source of the new species but the implications of its arrival. It is too soon to predict with real confidence, though the Rutgers researchers say there probably is no reason for alarm. "Because this species is very similar to cockroach species that already exist in the urban environment," says Evangelista, "they likely will compete with each other for space and for food." And as they compete, says Ware, "their combined numbers inside buildings could actually fall because more time and energy spent competing means less time and energy to devote to reproduction."
As for potential roach sightings on sidewalks and in parks during the dead of winter, encounters like that appear to be possible. "I could imagine japonica being outside and walking around," says Ware, "though I don't know how well it would do in dirty New York snow. The Asian researchers tested driven snow."
There also is little likelihood that the different species could interbreed and create a hybrid super-roach because their genitalia don't match. "The male and female genitalia fit together like a lock and key and that differs by species," Evangelista says. "So we assume that one won't fit the other."
Still, having a new six-legged neighbor could be unsettling. Ware has advice for New Yorkers who want to see fewer roaches, whatever the species. Some tips are obvious – sweep and vacuum so that food is not on the floor, and reduce clutter – while one suggestion may not be. Ware says using a dehumidifier could cut their numbers, because very dry air harms the cockroaches' egg cases and reduces their ability to reproduce.
New Jerseyans, being right across the river, also have a more than casual interest in the new species. So far, Ware says, there have been no documented New Jersey sightings, but "they do very well as hitchhikers."
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