Tough Bugger

Fearless cockroach hunter Coby Schal investigates how insects communicate via chemical cues, then subverts those signals for pest control.

By | March 1, 2013

Blanton J. Whitmire Distinguished Professor
of Structural Pest Management
North Carolina State University
Coby Schal’s first attempt at fieldwork was short-lived. In 1978, as a graduate student at the University of Kansas, he arrived in Costa Rica to observe cockroach aggression in the wild. Unfortunately, the first place he looked for his subjects was at the bottom of hollow trees packed with bats, which required picking through piles of moist guano where cockroaches feed.

“I got really sick,” says Schal. “I got a massive fungus infection in my lungs.” He spent the rest of his first 2 weeks in Costa Rica in the hospital, then was transferred to New York University Langone Medical Center, where he spent months recovering, including nightly treatments with an experimental antifungal drug. “It was just awful,” says Schal. “And that was my initial experience with biology.”

But the illness wasn’t enough to scare him away. “I went right back, and subsequently spent 3∏ years in Costa Rica,” says Schal, now an entomologist at North Carolina State University (NC State). “But I was not going back into those trees.” Instead, Schal watched cockroaches out in the fresh air, perched in the forest foliage during the night. There, with just a headlamp, pencil, and paper, he made two discoveries about cockroach pheromones and mating behavior that put him in the pages of Science in 1982, twice.

Not long after, Schal changed his field-study venue from the dense, infested forests of the tropics to the dense, infested apartments of cities, where he has pioneered the study of chemical communication by pests such as cockroaches, bed bugs, and more, and applied that knowledge to pest-elimination strategies, from baiting cockroaches in North Carolina to killing dengue-carrying mosquitoes in Peru.

“With cockroaches, I actually like going into homes and tracking them down. It’s like forensics—trying to think like a cockroach.”

Here, Schal shares some of his best cocktail party stories, including what male cockroaches give to their lady loves (hint: it’s not a box of chocolates), how to design killer insect traps, and where to check for bed bugs in a hotel room.

Schal from the start

Faint of heart. In 1972, Schal enrolled at the State University of New York at Albany as a varsity soccer athlete and premed major. “I did terrible in college. I thought I was invincible because I did so well in high school,” he says. “At the end of the first semester—and I’ll never forget this number—my grade point average was 1.87. I was put on probation and had to hunker down second semester to pull it up or else get kicked out. That was very embarrassing. It was also a check on my aspirations. I questioned why I was doing what I was doing. I realized premed was turning me off. I reached a conclusive decision on my first day of volunteering at a local hospital: they had me assist on a spinal tap, and I fainted. At that point, I decided to look at other options.”

Lovebug. Schal caught the entomology bug during his last summer of college, which he spent at the Cranberry Lake Biological Station in Upstate New York. “A single professor, Gerald Lanier, a forest entomologist and chemical ecologist, had a huge influence on me. He would take us out into the field, hiking in the Adirondacks, and show us all the insects around us.” But though Schal then decided to go for a graduate degree in entomology, he faced a major barrier. “Because of my first year in college, I could not pull up my GPA, so it was difficult to get into grad school. Although I applied to a bunch of grad schools, I didn’t get into a single one.” His girlfriend got into the entomology program at the University of Kansas, though, so Schal followed her there. “When I arrived, I talked to the department head, and he was great. He accepted me on probation and gave me an opportunity. And that’s all I needed. I went all the way through graduate school without financial support, but proved to them and myself that I was capable of doing the work.”

Bee aggressive. At Kansas, Schal hoped to study bees or wasps with entomologist Orley “Chip” Taylor, but cockroach researcher William Bell was looking for someone to study the insects in the tropics. “At that time, cockroaches were a very useful model system to study aggression, and I liked the idea of doing something unique in a remote place,” Schal says. But within a week of arriving in Costa Rica, he came down with that dangerous Histoplasmosis lung infection that sent him to New York for treatment. When he returned to Costa Rica, Schal made the observations that garnered him two papers in Science while still a PhD student: First, male cockroaches perch higher in the foliage than females as a way to detect female pheromones that rise with warm air; and second, after copulation, females feed on a nitrogen-rich excretion from their mating partner, a post-mating gift of a limited tropical resource. “But the Science editor told me that while he was interested in publishing [the first one], there was a problem. For several of the species, I didn’t know what the species were, and just called them species A, B, and so on. He said, ‘For us to publish it, you have to find names for these cockroaches.’ So I hooked up with a taxonomist and described four [new] species. I actually named one Epilampra belli after my professor, Bill Bell.”

Urban sprawl. After a postdoctoral stint studying gypsy moth pheromones at the University of Massachusetts, Amherst, Schal took a position at Rutgers University as an urban entomologist. “When I was looking for faculty positions, I had no idea there was a field called urban entomology. But Rutgers had an opening for someone to work in urban entomology; I got the position and became an urban entomologist. It’s a huge switch from nature and an open environment to working in people’s homes, the most artificial environment you can imagine. But it was a job, and at that time I thought it would be a stepping stone to being a tropical biologist.”

Cockroach chemistry. But soon Schal was committed to urban pests. Over the years, he and his collaborators have identified several previously unknown pheromones that cockroaches use to communicate with each other. “Cockroaches are amazing chemists. They make such diverse compounds,” says Schal. In 2012, his team published the discovery of an unusual long-distance sex pheromone produced by North American wood cockroaches. “It’s a laborious, difficult undertaking, because they produce really tiny amounts of these chemicals, and since the chemicals are new to science, they are very difficult to identify. In some cases, we’ve had to develop new approaches to be able to identify these chemicals.”

Stalking bloodsuckers. “About 5 years ago, very few researchers were interested in bed bugs; the bed bug problem was just beginning. At that time, we were doing work on population genetics of cockroaches, asking questions about the distribution and genetic connectedness of cockroaches. We thought similar types of questions could be asked about bed bugs.” Schal began collecting bed bugs, and now has more than 40 strains, kept alive with a rabbit-blood feeding system. In 2012, Schal and NC State colleague Ed Vargo genotyped groups of bed bugs within individual buildings to determine the dynamics of a bed bug infestation. “We can very convincingly show that in most cases, it’s a single infestation event that starts in a building. And because bed bugs are so resilient to inbreeding, you can have an infestation start from a single mated female and spread through the whole building. In other words, if you go to a thrift shop and pick up a chair, and don’t realize there are a few bed bug eggs attached to the underside of the chair, and you bring the chair home, as long as there are both males and females emerging from those eggs, you now have an infestation.”


Schal steps up

Calling all cockroaches. “Since 1984, I’ve been really interested in combining fundamental biology and applied biology. I always want to see what part of a project we can apply to pest control. Blattellaquinone, the pheromone we identified for the German cockroach in a 2005 Science paper, is an effective way to entice cockroaches into traps. You simply put the pheromone into a trap, and you can attract more cockroaches than if you had nothing or a food bait in a trap.”

Seducing skeeters. “A number of years ago, Charlie Apperson here at NC State and I started wondering what attracts female mosquitoes to lay eggs in specific places. We worked on the [dengue-carrying] yellow-fever mosquito, Aedes aegypti. It lays its eggs in small containers, and it’s selective about which containers it prefers. We started with a basic chemical ecology project with these mosquitoes, funded by the NIH, and now we’ve taken it to Peru, funded by the Bill & Melinda Gates Foundation, where we are using patented oviposition pots. In collaboration with Dawn Wesson from Tulane University, we place chemical attractants in these pots to attract female mosquitoes, and the pot contains insecticides on the inside, so the eggs and the mosquito are killed. In hundreds of homes in Iquitos now, we’ve been able to show a dengue reduction.” (For more on dengue fever, see “Bedeviled by Dengue.”)

With great power . . .“I get contacted by the public a tremendous amount, and it can make things very difficult. In my field, there is a tight connection between what we do in the lab and in public. When people call and say they have a bed bug problem, it’s difficult to say, ‘I don’t have time for you.’ I feel that it’s my responsibility to help because of the field that I’m in.”

Cockroach consultant. “We don’t only deal with the public, we also deal with the pest-control industry. I consult with a lot of companies, but I’ve made it a policy of mine that I don’t consult for a fee—I don’t charge companies so that I don’t have any conflicts of interest.” Schal consults, free of charge, for local and national pest-control companies, the Environmental Protection Agency, and the US Department of Housing and Urban Development. “Being at a state university that serves the taxpayers of North Carolina, I feel that it is part of our responsibility to do that.”

Bringing work home. “With cockroaches, I actually like going into homes and tracking them down. It’s like forensics—trying to think like a cockroach. You don’t have to worry about cockroaches coming home with you. With bed bugs, it’s tricky. Some of the places we go into, there are literally thousands and thousands of bed bugs. The walls are just crawling with them. And in those situations, it’s very easy to pick them up. There are a lot of hungry bed bugs, and after a blood meal, they can go into your pocket or the cuff of your pants. We have to be very careful.”

Angry coworkers. “We work in a building with lots of people, and raise lots of bed bugs, so there’s always the concern that bed bugs will get out from our rearing operation. If anyone in our building ends up getting bed bugs in their home, they’re likely to blame us. Of course, we have our genotyping approaches, so we could genotype their bed bugs and ours to prove that it’s not our fault.”


Schal of the wild

Roasted ants. “Unlike most entomologists, as a kid I don’t remember being infatuated with insects. I loved biology and nature and hiking, but I remember burning ants with magnifying lenses. That’s about the extent of my early interest in entomology.”

Science savvy. Born in Poland in 1954, Schal moved with his family first to Israel, then to New York City, where he attended public high school. “I came to the U.S. not knowing a single word of English. So it took a lot of effort to learn the language. But—and this says something about the Israeli education system—when I came here I was so far ahead in the sciences, I spent a whole year doing almost nothing but learning English and I did not fall behind in trigonometry, biology, chemistry, or things like that. I hate to say this, but the American science high school system wasn’t very good, and I don’t think it has improved a whole lot.”

Hotel heebie-jeebies. “Tomorrow, I’ll be staying at a hotel in Annapolis. I’ll have a little flashlight with me and a dental mirror—a tiny mirror on a stick. If I’m able to remove the headboard, I’ll actually lay it on the bed and look behind it. If I can’t, I reach back there with my mirror and light. I haven’t had a problem with bed bugs so far, but I always check. A few colleagues have found them.”

Working vacation. “My wife and I really enjoy traveling and nature hiking. When I’m in China, or anywhere in the Far East, I spend a lot of time looking for cockroaches. The center for diversity of the genus Blattella, which the German cockroach belongs to, is southeast Asia. When I was in Taiwan, we went hiking up to a Buddhist temple, and on the hike, every once in a while I would just stop and look in the leaf litter for cockroaches. I just like to find them. My wife bears with me. Sometimes she helps.”

Greatest Hits
• As a graduate student, discovered four new species of cockroaches and described two novel
cockroach mating behaviors
• Over 25 years, has isolated and described the chemical structure of several novel
cockroach pheromones
• Identified and tested a strategy to eliminate cockroach-produced allergens from homes
with asthmatic children
• Using DNA sequencing, described the dynamics of bed bugs infestation patterns
• Co-led a project testing the use of chemical attractants to lure and kill dengue-carrying
mosquitoes in Peru
• Assists government organizations and private companies to develop environmentally friendly approaches to pest control

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