WEDNESDAY, Jan. 19 (HealthDay News) -- Scientists studying the genetics of bedbugs believe they know how the critters become resistant to pesticides, and the finding could someday help drive them from homes, stores and offices across the United States.

"We are starting to scratch the genetic makeup of the bedbug," said lead researcher Omprakash Mittapalli, an assistant professor of entomology at the university's Ohio Agricultural Research and Development Center in Wooster. "This will give us a better understanding of the biology of the insect."

It was thought that a DNA mutation made bedbugs resistant to many pesticides, Mittapalli said. But these new findings suggest many genes have helped the insect adapt to commonly used pesticides, such as pyrethroids.

"Pesticide resistance is more complicated than we thought," Mittapalli said. It's possible that changes in the gene structure plus expression of other genes are responsible for pesticide resistance, he explained.

Exposure to pesticides actually may trigger genes to react in defense, leading to a new and dominant strain of pesticide-resistant bedbugs. This type of evolutionary adaptation occurs throughout the insect world, and is not unique to bedbugs, he said.

Their findings won't have an immediate impact in the fight against the blood-feeding insects, Mittapalli said, "but the genetic basis of some of these genes could be used in new control strategies."

Widespread use of DDT and other long-lasting insecticides helped to control bedbugs after World War II, but over the past decade their numbers have increased as much as 500 percent in North America and other parts of the world, according to background information in the study.

These infestations cost homeowners and businesses billions of dollars a year and require the use of large amounts of pesticides, many of them ineffective, Mittapalli noted.

For the study, published online Jan. 19 in the journal PLoS ONE, Mittapalli's team studied the DNA and RNA of laboratory-raised bedbugs that are susceptible to insecticides and bedbugs previously exposed to pesticides from an apartment in Columbus, Ohio.

The researchers identified 35,646 expressed sequence tags -- many more than previously known -- which are vital in gene discovery and sequencing. These tags reflect the bugs' diverse genetic abilities, Mittapalli said. "These are the RNA molecules being expressed after a good meal of blood," he said.

Bedbug expert Jerome Goddard said "one of the big problems is that we can't seem to kill them [bedbugs] very well."

The bugs are resistant to the pyrethroid insecticides most pest controllers use, and "these scientists are trying to figure out which genes play a role in that insecticide resistance. I guess to maybe someday manipulate that resistance," said Goddard, an associate extension professor of medical and veterinary entomology at Mississippi State University, in Starksville.

Missy Henriksen, a spokeswoman for the National Pest Management Association, said that any research being done to further understanding of bedbugs in terms of eradicating them "is all good."

The current bedbug scourge has its roots in the ease of modern-day travel, Henriksen said. "Bedbugs need humans for their very survival," she said. Picking up bedbugs and bringing them home is the number one way infestations start, she noted.

Growing pesticide resistance means that "a product that may be effective in killing bedbugs in Kentucky may not be as effective in killing bedbugs in Ohio," she said.

For now, Henriksen advised calling a professional to rid your house of bedbugs if you have them.

To prevent them from taking hold in the first place, inspect furniture or clothing before bringing them into your home, she said. When you travel, inspect your hotel room for bedbugs and keep bags off the floor and off the bed, she added.

After traveling, wash the clothes you took on your trip in hot water or use a hot dryer to prevent any bedbugs from lodging in your home, Henriksen said. Similarly, because bedbugs have been found in retail stores, she suggested washing new clothing or bedding before using it.

More information

For more information on bedbugs, visit the U.S. National Library of Medicine.