Researchers study biology of bedbugs

 Most people would probably prefer not to think about the possibility of tiny critters infesting their cozy beds; however, Coby Schal, a professor of entomology, along with other researchers at N.C. State, said they developed a curiosity in bedbugs and took one for the team by performing a ground-breaking study on these pesky pests. 

“Bedbugs drew us into it,” Schal said. “My group has worked on cockroaches for eons, and we tend to work on things that the public is concerned about in homes especially. About 15 years ago, no one cared about bedbugs, but now this massive, global resurgence that’s taking place is really the reason why we started working on them.” 

Schal explained that working with and studying bedbugs is a tedious and time-consuming procedure. He said roaches are much easier to maintain because, unlike bedbugs, they do not need blood to survive.

“When I say we started working on them, the first step is to rear them,” Schal said. “Bedbugs are difficult to raise. Bedbugs suck blood like mosquitos do, except there is a huge difference between the two. First of all, with mosquitos, the babies are larvae, they live in water and they don’t bite. Also, only the female portion of the population bites. With bedbugs, every single member of that population bites so as the population grows, every single one becomes problematic.” 

This demand for blood caused a bump in the road for Schal and his team. They needed to figure out how they were going to supply the bedbugs with their source of nutrition. Schal said bedbugs have to be fed about every seven days. 

“This problem with bedbugs drew us into studying them,” Schal said. “The first obstacle is to develop a process where we can raise bedbugs.” 

Schal and his team responded to this problem with a trial and error approach. He said they concluded that ultimately there are three ways to feed and raise bedbugs. First, Schal said he volunteered himself as the main feeding source by actually placing the bedbugs on his own flesh for them to attack. He said this worked for about two weeks at which point his body started to develop an allergic reaction to the bites. 

The second approach Schal discussed was the possibility of bringing animals such as guinea pigs or rabbits into the lab and letting the bedbugs latch and feed off of them. 

“Using live animals can be controversial because there are so many law regulations and we don’t want vertebrate animals in our laboratory,” Schal said. “So that was the second approach that we never pursued.”

Schal and his teams’ third and final approach was putting together a system to feed them off blood that does not require animals. 

“We buy rabbit blood, and we put it into a sort of water-jacketed object, and we warm the water up,” Schal said. “To the bedbugs it’s like a human.”  

Schal said once he and his team found this to be successful, they could go on with their research and maintain and watch the bedbugs.

“It’s critical not only to maintain them but to have vast colonies,” Schal said. “We have 100s of 1,000s of bedbugs in the lab. We also collect bedbugs of peoples’ homes. We bring them into the lab and we culture them so that we can study their biology because bedbugs in different homes have different characteristics, even though they’re the same species.” 

Schal said most of he and his teams’ projects have to do with questioning and finding out about the origin of bedbugs. 

“We take what’s called a population genetics approach where we do genetic tests on bedbugs just like paternity tests for humans,” Schal said. “The beginning of our work was to try to understand why suddenly we have this huge inundation of bedbugs throughout society. We looked at the population genetics of bedbug collections from all over the United States. Our conclusion is they are coming in from other countries because the genetic diversity that we see in the U.S. is huge due to all the internationalization and travel going on in the world.”

Schal said while all this research was being discovered, his team was still culturing bedbugs in the laboratory, but before all this, he said they had done a lot of work with cockroaches which would help prep them for their encounter with the bedbugs. 

“With cockroaches, we had done this type of work for about two decades now, showing that cockroaches in groups grow faster than cockroaches in isolation,” Schal said. “So we hypothesized based on the cockroach work that the same thing would be the case for bedbugs. The idea was insects that live in groups should facilitate each other’s growth, whereas insects that live in isolation should not care much about being in a group.” 

Schal explained that insects like bedbugs and cockroaches tend to live in groups because they have aggregation pheromones. 

“Pheromones are these chemicals that promote communication within a species,” Schal said. “Aggregation pheromones attract members of the same species to an aggregation. The aggregation actually facilitates their development.”

Schal noted that all of this is actually the work of a graduate student at N.C. State. 

Schal said they hope to get a better understanding of the physiological pathway that is involved. 

“We want to know how the bedbug senses that it’s in a group,” Schal said. “Is it through chemicals that are produced in the group, is it through vision or is it through contact or a tactile type of stimulation? In cockroaches, we have solved that problem and we have shown that it is tactile.”