A species of cockroach, never before seen in the United States, has now been identified within Manhattan, New York. The hardy insect can not only survive the warm temperatures of indoor areas, but is also tolerant to the inhospitably freezing temperatures of winter climates.
The cockroach species in question, Periplaneta japonica, is common across many parts of Asia. The japonica species had not been observed in the U.S. until insect biologists at Rutgers University, New Jersey, documented their existence in a study published in the latest issue of the Journal of Economic Entomology.
The Hitchhiking Cockroach
Researchers Dominic Evangelista and Jessica Ware conducted the investigation after the predominately Asian species was initially sighted by a New York exterminator, during 2012. The exterminator was performing duties on the High Line – a former New York Central Railroad branch, redesigned as an aerial greenway – situated on Manhattan’s West Side when, much to his surprise, he stumbled across an unusual looking roach. With great forethought, he acquired the cockroach’s carcass and dispatched it to the University of Florida for further inspection.
Study co-author Lyle Buss was the first recipient of the roach remains. Buss contacted the Smithsonian who, in turn, sought the expert opinion of Ware, since she had previously published a number of papers on cockroaches.
Operating in Ware’s lab, Evangelista commenced barcoding studies to determine the genetic characteristics of the species. After the team’s thorough analysis was successfully completed, they came to the conclusion that Periplaneta japonica cockroaches inhabited Manhattan’s High Line.
Ware and Evangelista tentatively posit a connection between the cockroach’s arrival and the vegetation that scours the makeshift linear park. The pair explain that some of the plant nurseries throughout the U.S., where a variety of plants are propagated and grown, often import non-native flora; in doing so, it is conceivable that some of the roaches arrived in the soils of the plants, which were then used to adorn the High Line.
Periplaneta japonica Tolerant to Winter Temperatures
Ware, who is assistant professor of biological sciences at Rutgers University, explains how the cockroach’s tolerance to the harsh, winter temperatures was studied by colleagues in Japan, some 20 years ago:
“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.”
Adults are between 2.5 and 3.5 centimeters in length and have a glossy, black/brown body. Adult males and females can be differentiated by the variation in wingspan length; males’ wingspans exceed their body length, whereas females wingspans are usually only half their overall body length.
The nymphs of the durable species can hibernate at sub-freezing temperatures. A paper published in 1971, entitled Outdoor hibernation of Periplaneta japonica (Blattaria : Blattidae) in snowy area, established that the cockroaches concealed themselves in between the splits of decayed wood, amidst the heavy snowfall in the Japanese city of Japan, Kashiwazaki. The nymph were capable of surviving the winter period at sub-zero temperatures, typically lasting a two month spell.
Similar studies have also revealed that the nymphs can survive lab-based supercooling experiments, where researchers had subjected them to tissue freezing for up to 12 hours.
In addressing the implications for New York citizens, the Rutgers researchers do not believe they represent any serious concern. Elaborating on this thought, Evangelista explains the cockroaches to be relatively similar to the extant cockroaches that are already scurrying around the urban environment. If anything, Ware theorizes that the increased competition between the different species of cockroaches could confer beneficial effects, as they vie for scant resources:
“… their combined numbers inside buildings could actually fall because more time and energy spent competing means less time and energy to devote to reproduction.”
The researchers suggest that the “dirty New York snow” could also serve a purpose in stifling population numbers of japonica. Interbreeding between the different species of cockroach is thought to be highly unlikely too, an important factor that ensures their limited dissemination; the male and female genitalia are said to fit together like a lock and key, which differs between species.
Ware offers some informative advice to those New Yorkers hoping to keep the roaches at bay. She recommends clearing food debris from floors and other household surfaces, as well as using a dehumidifier; the resulting dry air will negatively impact egg cases of Periplaneta japonica, impeding the winter-tolerant cockroach’s ability to reproduce.
By James Fenner