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Bedbug Gene Mapping May Yield Critter's Secrets

Researchers find the insects have remarkable natural defenses

By Dennis Thompson
HealthDay Reporter

TUESDAY, Feb. 2, 2016 (HealthDay News) -- Bedbugs have been making humans' skin crawl for thousands of years as they creep out of their hiding places in bedding at night to feast on people's blood, leaving an itchy, tell-tale rash in their wake.

Now, a complete analysis of the pests' entire genetic structure has provided researchers with fresh insight into the hardy nature of bedbugs -- and also highlights some of the weaknesses that humans can exploit to better control the bugs.

Bedbugs have incredible natural defenses that protect them against pesticides, but they also appear to be particularly vulnerable at specific points during their life cycle, researchers report in a pair of studies published Feb. 2 in the journal Nature Communications.

Bedbugs have genes both inside their bodies and in their thick, armored skin that help detoxify insecticides and improve resistance to the pest-controlling chemicals, the researchers found.

But true to the vampiric nature of bedbugs, these protective genes don't appear to kick into effect until the pests have grown up and feasted on their first meal of human blood, said Christopher Mason. He is an assistant professor of physiology and biophysics at Weill Cornell Medicine in New York City, and senior author of one of the new studies.

"We found in the genetic code some hallmarks of insecticide resistance, and we found that some of those are more vulnerable during early development," Mason said. "A lot of genetic activity of the organism is really in its first stages of life, right as it's eating its first blood meal. This is potentially when it's most vulnerable to insecticides."

Bedbugs are flat insects ranging from 1 to 7 millimeters in size. Seven millimeters is roughly the size of Lincoln's head on a penny, according to the U.S. Centers of Disease Control and Prevention (CDC). Reddish-brown in color, bedbugs feed solely on the blood of people and animals while they sleep, the CDC noted.

During the past two decades, bedbugs have enjoyed a global resurgence in every continent except Antarctica. In Australia, infestations have increased a whopping 4,500 percent, authors from the second study reported.

To best these pests, dozens of researchers signed onto one of two separate efforts to break down the entire genetic structure of the bedbug.

The genetic examination of the bedbug revealed that the insects' armor-like outer shell serves as a barrier against pesticides in two ways, said co-author of the second study, Ameya Gondhalekar. He is an assistant professor of entomology at Purdue University in West Lafayette, Ind.

The shell itself is thick, which keeps insecticide from easily seeping into the bug, Gondhalekar said. But on top of that, the shell contains detoxification genes that help further break down insecticides as they pass through.

"When the pesticide is trying to penetrate into the insect body, it's getting degraded as soon as it enters it," he said.

A bedbug also flouts pesticides by relying on bacteria located on its skin and inside its body, Mason said. The main role of these bacteria is to help the bedbug break down blood for digestion, he added.

"One of the important characteristics of all blood-feeding insects is when they feed on blood, it's pretty difficult to digest and contains a lot of chemicals that can be toxic to the insects," Gondhalekar said. "They need to detoxify it, and at the same time also use it as a source of nutrition."

But these bacteria also appear to be helping bedbugs by breaking down life-threatening pesticides before the chemicals can do damage, Mason said.

By pounding away at the resistant pests with insecticide, humans may have unknowingly aided their surge in population, Mason said. That's because the insecticides are more likely to kill off cockroaches than bedbugs.

"Cockroaches are a natural predator for bedbugs," Mason said. "If you kill one, you might end up with more of the other."

From the genetic knowledge gathered by these research teams, pest control experts might be able to reformulate existing pesticides or develop new ones that would target bedbugs early in their life cycle, before resistance is strong, both Mason and Gondhalekar suggested.

Future pesticides might also feature some sort of antibiotic targeting the bacteria that aids bedbugs in their resistance, Mason added, noting that these bacteria don't serve a role in human health.

Jim Fredericks, chief entomologist and vice president of technical and regulatory affairs for National Pest Management Association, praised the efforts of the two research teams.

"This is important research despite the fact that the findings won't be immediately applicable in the field as part of bedbug management efforts," Fredericks said.

"Research like this is an integral part of the scientific process of elucidating the underlying genetic basis for bedbug biology and behavior. By identifying genes that are unique to bedbugs, research can continue toward identifying new, highly effective control methods that pest control professionals can employ against bedbugs," Fredericks added.

More information

For more about bedbugs, visit the U.S. Centers for Disease Control and Prevention.

SOURCES: Christopher Mason, Ph.D., assistant professor, physiology and biophysics, Weill Cornell Medicine, New York City; Ameya Gondhalekar, Ph.D., assistant professor, entomology, Purdue University, West Lafayette, Ind.; Jim Fredericks, Ph.D., chief entomologist, vice president of technical and regulatory affairs, National Pest Management Association; Feb. 2, 2016, Nature Communications

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