Monitoring for infestations of German cockroaches (Blattella germanica) in homes and buildings is hindered by a lack of effective and practical attractants, but researchers at Rutgers University say a mix of extracts from apple and blueberry has proven highly effective in lab and field settings and could lead to more successful cockroach integrated pest management programs. (Photo by Martin Grimm, via iNaturalist, CC BY-NC 4.0)

By Edward Ricciuti

Ed Ricciuti

If building a better mouse trap will bring the world to your door, engineering one for cockroaches that works where others don’t could well draw crowds from throughout the galaxy. Assuming life exists in the great beyond, it conceivably includes cockroaches, preeminent survival experts most noxious, and they probably are as detested out there as they are here. They spread disease, contamination, stench, allergies, and other unpleasantries, so news that scientists have pinpointed a brew they say conclusively attracts cockroaches to traps is bound to draw the attention of people who battle the ubiquitous insects.

The research, published this month in the Journal of Economic Entomology, was oriented toward novel food-based attractants that could be used with sticky traps to monitor cockroaches for evaluating and planning control programs. Says Changlu Wang, Ph.D., of Rutgers University, “The findings can be immediately applied by professionals as well as consumers for better monitoring cockroach infestations. The lures may be used in combination with traps to detect cockroaches and evaluate the effectiveness of IPM [integrated pest management] programs.” Wang worked on the project, headed by Salehe Abbar, Ph.D., of Kansas State University, who was then his postdoctoral research associate.

The target species of the research was the introduced German cockroach (Blattella germanica), the most common species of cockroach in the world and arguably the worst pest of the bunch. At present, few if any workable attractants are commercially marketed for German cockroaches. Currently, highly effective and economical cockroach attractants are not available, according to the authors. Simply put, cockroach lures in general leave lots to be desired. The U.S. Environmental Protection Agency does not require independent research data certifying the effectiveness of many pest control products, so claims of manufacturers as to their effectiveness can be iffy, says Wang.

To evaluate various attractants for German cockroaches (Blattella germanica), researchers at Rutgers University tested traps baited with attractants in both the laboratory (shown here) and in homes and buildings. This lab setup contains baited and unbaited traps, two German cockroach harborages, and water and food sources. (Photo courtesy of Changlu Wang, Ph.D.)

Effective control of an insect pest infestation depends on an accurate assessment of its numbers in the target area, which in turn depends on monitoring and extrapolation of a resident population from individuals caught in traps. Counting cockroaches by eye seldom works because they are excellent at escape and evasion, easily hiding in cracks and crevices. The problem as far as German cockroaches is concerned is that the standard way of catching them is pretty much hit or miss, since the type of sticky trap used to do the job is not equipped with attractant. “Sticky traps are standard tools for monitoring German cockroaches,” say the authors. “However, because they lack an attractant, their ability to catch cockroaches is by chance and largely dependent upon the location of placement and length of time they are left in place.”

Food-based attractants like those in the study not only can make monitoring more effective but also might be incorporated into baits used to lure cockroaches to their doom. Potentially, says Wang, these concoctions can “be used to combine with existing cockroach baits to increase the palatability of cockroach baits, which is the most effective method to control German cockroaches. But we need to do tests about this concept.”

A variety of food-based baits are used in traps to kill cockroaches, including bread and beer, dog food, cockroach feces, apple, yeast, and peanut butter. These can present problems, such as foul odors and, in the case of peanut butter, endangering people with a peanut allergy. Attractants such as peanut butter and beer-soaked bread, moreover, are not compatible with sticky traps, typical of which is a gooey glue board. Instead of the food itself, the study employed food-derived extracts or volatiles.

To evaluate various attractants for German cockroaches (Blattella germanica), researchers at Rutgers University tested traps baited with attractants in both the laboratory and in homes and buildings, shown here. (Photo courtesy of Changlu Wang, Ph.D.)

Rutgers University’s Changlu Wang, Ph.D. (picutred here) and postdoctoral associate Salehe Abbar, Ph.D., now at Kansas State University, studied various attractants for German cockroaches (Blattella germanica), reporting their results in a new paper in the Journal of Economic Entomology. After tests in both lab and onsite in homes and buildings, they say a mix of extracts from apple and blueberry has proven highly effective and could lead to more successful cockroach integrated pest management programs. (Photo courtesy of Changlu Wang, Ph.D.)

The hottest lure, tried during experiments both in the laboratory and in the field at affordable housing apartments in New Jersey, was a mix of apple and blueberry oils and a commercial roach lure in tablet form, according to the researchers. Adding a dash of bacon extract worked well in field studies, too.

According to the paper, laboratory results showed that sticky traps containing attractants such as apple oil, blueberry oil, orange oil, fish oil, peanut butter, bacon extract, and Catchmaster roach lure tablet “had significantly higher trap catch compared to those traps that do not contain an attractant. … Both apple plus blueberry oil and roach lure tablet increased the trap catch by more than 103 percent compared to unbaited traps in the field studies.”

“The attractiveness of apple plus blueberry oil was similar to roach lure tablet in the field studies,” they write. However, in laboratory studies, apple plus blueberry oil was significantly more attractive to German cockroaches than roach lure tablet.

The attractants studied have great potential as highly sensitive detection tools in environments such as hospitals, hotels, and restaurants, where zero tolerance for cockroaches is essential, say the researchers.

Ed Ricciuti is a journalist, author, and naturalist who has been writing for more than a half century. His latest book is called Bears in the Backyard: Big Animals, Sprawling Suburbs, and the New Urban Jungle (Countryman Press, June 2014). His assignments have taken him around the world. He specializes in nature, science, conservation issues, and law enforcement. A former curator at the New York Zoological Society, and now at the Wildlife Conservation Society, he may be the only man ever bitten by a coatimundi on Manhattan’s 57th Street.