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<p>If you have roaches, you can put down a small plastic trap to control their spread. But there are no such traps for bedbugs … yet.
By Rose Hoban
There’s a distinctive smell to bedbugs. It’s hard to describe, kind of musty, kind of sickly sweet, kind of spicy.
Walk onto the third floor of Gardner Hall in the middle of the NC State University campus and you can get a good whiff of that smell, and others. That’s where a group of entomologists studies household pests in rooms stacked with vials of bedbugs and boxes of roaches.
Don’t visit if you’re squeamish.
Those scientists are on a surprisingly difficult quest – for a cheap, effective and relatively nontoxic-to-humans way to get rid of bedbugs.
Essentially, they’re seeking the equivalent of the “roach motel.” But it turns out bedbugs are not as cooperative as roaches.
In the past 15 years, bedbugs – those little critters that live in beds and bedrooms and couches and behind baseboards – have made a resurgence. There are websites dedicated to tracking reports of bedbugs in hotels and apartment complexes. There’s bumper business for dogs to track their presence (using that distinctive smell), and there’s plenty of pricey work for exterminators to kill them, either with chemicals or heat, or both.
But the technology for killing them hasn’t advanced much since bedbugs reappeared on the scene, said Angela Sierras, a doctoral student in entomology at NC State.
“I formerly was a pest-control tech in North Carolina. We were just seeing these huge increases in infestations, and the inability to manage them was frustrating,” Sierras said during a break at the annual meeting of the Southeastern Branch of the Entomological Society of America, held in Raleigh earlier this month.
“We would spend four or five hours in a place, spraying, dusting, doing everything we could to try to control an infestation, and we just could not do it,” she said. “It was ridiculous the amount of callbacks we were getting.”
Recognizing the need for a better way is what drove Sierras back to school to research creating a “bedbug motel,” something similar to bait traps used to control roach infestations.
She found kindred spirits at NC State, where there’s been an active bedbug research lab for years.
There are three components to making an effective bedbug bait, said Zach DeVries, another NC State entomology doctoral student.
“We have to have an attractant, something to get the bug to the bait; a feeding stimulant, something to induce feeding once they arrive; and an active ingredient, something to actually kill them or to stop them from laying eggs or to stop those eggs from hatching,” DeVries said.
Roaches’ lack of discretion in what they’ll eat makes them an easy target for bait traps. Put out a goo that smells right, add an insecticide, and the roaches “check in, but they don’t check out.”
But bedbugs are more complicated. They’re very picky eaters.
“If you put a dot of blood on a plate, they won’t feed on it freely,” DeVries said. They want to stick their proboscis through something. “It would have to be a membrane, but what it would be, we don’t know.”
In the lab, the entomologists had been using a manufactured membrane called Nescofilm, but the manufacturer stopped making it, and they’re down to one last box of the stuff. They recently figured out that grafting tape that’s stretched out will work to feed all their bedbugs the half liter of rabbit blood they suck up during a given week.
Another question needing an answer was what, exactly, attracts the bugs? It turns out they’re attracted to adenosine triphosphate, or ATP, the molecule that powers cellular activity in most animals, including humans.
“You can get bugs to feed extremely well by having simply saline with ATP in it, and that’s all they need to get them to feed,” DeVries said.
“To grow a bug … that’s a question that we don’t know. How to get them to molt and lay eggs – we don’t know what would be a solid artificial diet.”
The final problem is finding the right chemical to kill the bedbug, one that won’t turn off a bedbug’s sensitive taste buds.
“Then we have to think about, ‘OK, how do we make this realistic, and last out in the field, and last for more than a few hours,’” DeVries said.
One problem with bedbugs is that they’re not really a problem, medically speaking.
In the past, there was a lot of research to see if bedbugs can transmit disease. And by current estimations, the answer to that question is no, said Mike Fisher, a graduate entomologist at NC State who studies what grows in the guts of bedbugs.
“They still have not largely been associated with a disease or pathogen,” Fisher said. “They maybe never will, because the epidemiology of disease vector complex is so unique to them. Unlike mosquitoes, that can spread around and easily move around, bedbugs largely stay in the same place.”
That lack of disease transmission has meant there’s little money for medical research; most research grants come out of the pest-control industry, Sierras said.
Some “proof of concept” studies have shown bedbugs could, under the right circumstances, transmit Bartonella or Chagas disease, a deadly problem concentrated in Central and South America, said DeVries.
Disease transmission has not yet been documented, DeVries and Fisher made clear, but the fact that diseases could be transmitted indicates there is probably more cause for concern. They said, for example, diseases could be spread after a bedbug poops onto a human host, the human scratches and bacteria in the feces gets rubbed into broken skin.
“There are tons of things out there that are pathogenic to humans,” DeVries said. “We have no idea of their capability of transmitting some of these other viruses, partly because no one has investigated these.
“So there’s a possibility that they’re transmitting all kinds of things.”