Bedbug War Continues; Scientists Study Bug Genome for Weaknesses

ABCNews.com
Thursday, January 20, 2011

As the war on bedbugs wears on, scientists try to understand the invasive pests so they can kill the suckers.

Now, Ohio State University researchers have conducted the first genetic study to identify pesticide-resistant genes the bugs carry. It may lead to new ways of controlling the bugs in the future.

"Right now, these studies are still preliminary and only scratching the surface of the bedbug genome," said Omprakash Mittapalli, Ph.D., assistant professor of entomology at Ohio Agricultural and Development Center and corresponding author of the study. "But bedbugs could be a lot more complicated than previously thought."

Mittapalli and his team analyzed laboratory-reared bedbugs vulnerable to insecticides, and compared them to pesticide-exposed bedbugs found in a local apartment in 2009 and 2010. Researchers identified more than 35,000 expressed sequence tags, tiny portions of a gene that can be used to help identify unknown genes and map their positions within the genome.

"The genetic bases for these genes could enable us to formulate newer development strategies that may be more effective than what we have right now," said Mittapalli. "But a lot more studies need to be done, not only to identify candidate genes, but also to get a better understanding of the biology of the insect."

The study, published in the journal PLoS ONE, found that there were differences in a gene, known as CYP9, between the bedbugs exposed to pesticides and the non-exposed bedbugs.

In other words, scientists say bedbugs may be genetically resistant to the pesticides currently used to get rid of them.

"If we can suppress the expression of that gene and see if bedbugs are still able to overcome the pesticide, then we'll be able to see that that gene is involved in overcoming pesticide resistance," said Mittapalli.

Jim Fredericks, director of technical services at the National Pest Management Association, said that the preliminary genetic findings are an important step in the total bedbug extermination process.

"Bedbug research came to a standstill about 40 years ago when people thought that bedbugs were gone, so the basic biology in terms of today's standards has never been investigated," said Fredericks. "By looking at the genomics of the bug, we start to get a better picture of how these things work, especially in terms of pesticide resistance."

And in a press release, Mittapalli said that pinpointing such defense mechanisms and the associated genes could lead to the development of novel methods of control that are more effective.

Bedbugs are flightless, nocturnal parasitic insects that were first noticed in the United States in the early 1700s. They afflicted Americans until World War II, when the extensive use of DDT wiped out most of the pests.

But when DDT was banned, the bedbugs came marching back in. Over the past decade, almost every continent has recorded bedbug infestation, with an estimated 100 to 500 percent annual increase. The bedbug plague has forced people to spend billions of dollars on treatments. And the pests have been known to resurface in homes and buildings weeks or months after extermination.

Scientists say the banning of DDT is just part of the reason. They also cite greater foreign travel, more frequent exchange of second-hand furniture and clothing and the bugs' increasing resistance to pesticides.

While the bugs do not transmit disease, people allergic to bedbug bites can experience itching, burning or dermatitis. A bedbug infestation can also cause anxiety, insomnia or worsen an existing mental health condition.

For now, Fredericks said that bedbug infestations are dealt with on a case-by-case basis, but the pest management can include fumigation, steaming and vacuuming infested areas, and a whole-room heat mechanism, in which the temperature in an infested room is raised above 120 degrees. That's lethal for the bugs and their eggs.

Missy Henriksen, vice president of public affairs for the NPMA, said that the overall risk of getting bedbugs is still small. And bedbug infestaton has nothing to do with social status.

"There is this social stigma incorrectly associated with bedbugs," said Henriksen. "Bedbugs will come into a clean environment just as easily as a dirty environment. And, while people should practice protective to avoid bedbugs, it's through no fault of their own if they get them."

While it's not the golden ticket, Henriksen said vigilance is key when trying to prevent bedbugs. She gave a few key recommendations to prevent bedbugs from living with you.

When trying on clothes in a store, be sure to inspect the clothes before putting them on, and place your purse and shopping bags on a hook, not the floor. Unfortunately for those who love a second-hand unique find, don't bring home furniture left curbside. If you do buy second-hand goods, make sure you know their origin.

When traveling, keep your suitcase off the floor, and when returning home, inspect and wash your clothes in hot water.

"It doesn't matter if it's a five-star resort, you have to be careful," said Henriksen.

And in the meantime, as we all try and prevent bedbugs from hitchhiking their way into our homes, scientists will continue to work to understand the inner workings of the insect.

"We're interested in effective and safe treatments that are approved by the EPA, along with continued research, basic biology and applied biology of bedbugs," said Fredericks. "In the meantime, vigilance is an important part of the process."