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Gory Details

The bizarre side of science
Erika Engelhaupt

Gory Details

New Yorkers should relax about new roach species

Male (left) and female Japanese cockroaches have been found living under the boardwalk and in mulched areas of New York City’s elevated High Line park.

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A Japanese roach species has turned up in New York City’s High Line park, and from the headlines so far you’d think Godzilla had waded across the ocean. It’s the first time the roach has been spotted in the United States, having already invaded China and Russia. And unlike native house roaches, it may be able to survive outdoors in New York’s cold winters.

But fear not, New Yorkers. The invasion might even be a good thing. The new roaches have a few things going for them, including one upside I found that scary news reports have not mentioned: We might be less allergic to them.

Overall, “I don’t think any disaster is going to happen,” says Mark Stoeckle, who runs the National Cockroach Project at New York City’s Rockefeller University. “I think we’re going to be OK.”

The invaders turned up when an exterminator found some unusual-looking roaches around trees and under the boardwalk of New York City’s elevated High Line park. To identify the species, Rutgers University entomologist Jessica Ware and graduate student Dominic Evangelista used DNA barcoding to find short stretches of signature DNA. The newcomer turned out to be the Japanese cockroach, Periplaneta japonica.

My advice to Manhattanites is to get to know these new neighbors. Periplaneta japonica is slightly smaller and darker in color than the American cockroach, P. americana, which you might know as “the big ones.” The other common house roach found in the United States is the German cockroach (“the little ones”). There are also various roach species that live outdoors, which works out fine for everyone: We can pretend they don’t exist, and they can avoid being killed by a shoe.

As in Ware’s lab, Stoeckle and his team of students use DNA barcoding on roaches sent to them from around the country to see how U.S. roaches differ regionally or within a city. They’ve found that New York City’s roaches form genetically distinct groups, each sticking to its own neighborhood. “They do coexist within the city, but they’re quite segregated,” he says.

So far, Japanese roaches have only been found outside. But if they do move indoors, there’s a chance they might ease our allergies a bit. Cockroach allergies are one of the most common allergy types, and contact with roaches directly or through their feces or saliva can trigger symptoms or worsen asthma. But here’s the good news: A Japanese study of asthmatic children found that a smaller percentage of the kids were allergic to the Japanese species compared with the two most common American roach species (about 16 percent for the Japanese roach compared with 29 percent for the German and 20 percent for the American).

The researchers who identified the High Line roaches write in their paper, published in the December Journal of Economic Entomology, that the new roaches “may not contribute as greatly to degradation of indoor air quality and the transmission of surface pathogens as other species that are more restricted to the indoors.”                                                                      

And a little competition among roach species might not be a bad thing, either. On one hand, the greater cold tolerance of the Japanese roach might allow it to occupy a somewhat different niche than American or German roaches, so the three species may be able to coexist. But Ware also notes in a Rutgers press release that the invader will have to duke it out for food and space on American roaches’ home turf if it moves indoors. “Their combined numbers inside buildings could actually fall because more time and energy spent competing means less time and energy to devote to reproduction,” she said.

As for the roaches’ cold tolerance making them superbugs, I’m not convinced. The roaches that already invade American houses seem to do just fine despite relying on human heat sources during cold weather. P. japonica’s cold tolerance may just mean it tends to stay outside where it has the competitive advantage in winter. It would still be an invasive species, and I’m not saying invasive species are good, but it’s likely that if the new roach stays outdoors, humans would just ignore it.

We’ll have to keep an eye on the newcomers to see what they do. In the meantime, if any of you are lucky enough to find one (as I’m sure the High Line will now be crawling with people looking for roaches), you may get to see another reason to appreciate these new roaches. According to a study in 1980, Japanese roaches produce a viscous secretion that they use to fend off attacks from aggressive ants. The roaches shake their butts to fling droplets of the fluid onto the ants. The secretion “appears to contain no noxious component,” the Japanese researchers reported, but the ants “were rendered helpless.”

Come on now, New Yorkers, that’s cool.

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