After World War II, bedbugs ravaged the world, but in the 1950s they were almost completely eradicated with the insecticide dichlorodiphenyltrichloroethane (DDT). This chemical was later banned. Since then, this urban pest has made a comeback worldwide and has developed resistance to many insecticides used to control them.
A study published in the Journal of Medical Entomology details how a research team from Virginia Tech, led by urban entomologist Warren Booth, discovered a gene mutation that can lead to pesticide resistance.
These findings were the result of a study Booth designed for graduate student Camille Block to develop her skills in molecular research.
”It was purely a fishing expedition,” said Booth, an associate professor of urban entomology in the Joseph R. and Mary W. Wilson College of Agriculture and Life Sciences.
Booth, an urban pest specialist, already knew about a gene mutation in the nerve cells of German cockroaches and whiteflies that conferred pesticide resistance. Booth suggested Brooke analyze one sample of bed bugs from each of the 134 different populations collected by a North American pest control company between 2008 and 2022 to determine whether they carried the same cellular mutation. The results showed that two bed bugs from two different populations carried the mutation.
”This (discovery) was actually made based on my last 24 specimens,” said Block, who studies entomology and is a member of the Invasive Species Collaboration. “I’ve never done molecular biology before, so learning these skills is crucial for me.”
Because bedbug populations are genetically very homogeneous, primarily due to inbreeding, one sample from each population is usually sufficient to represent the entire group. However, to verify that Brock had indeed discovered the mutation, Booth tested all samples from the two identified populations.
”When we retested several individuals in both populations, we found that they all carried this mutation,” Booth said. “So they became established as carriers of these mutations, and these mutations are the same ones we found in German cockroaches.”
Through his research on German cockroaches, Booth learned that their resistance to pesticides was due to gene mutations in the cells of their nervous system, and that these mechanisms were dependent on the environment.
”There’s a gene called the Rdl gene. It’s been found in many other pest species and is associated with resistance to the insecticide dieldrin,” said Booth, a researcher at the Fralin Institute of Life Sciences. “This mutation is present in all German cockroaches. Surprisingly, we haven’t found a single population that doesn’t carry this mutation.”
According to Booth, fipronil and dieldrin—both insecticides proven effective against bedbugs in laboratory studies—have the same mechanism of action, so theoretically, this mutation could lead to the development of resistance to both drugs. Dieldrin has been banned since the 1990s, but fipronil is still used for topical flea treatment on dogs and cats, not for bedbug control.
Booth suspects that many pet owners who use fipronil drops to treat their pets allow their cats and dogs to sleep with them, exposing their bedding to fipronil residue. If bed bugs enter such an environment, they may unintentionally come into contact with fipronil and become predisposed to the proliferation of this variant within the population.
”We don’t know whether this mutation is new, whether it appeared later, during that period, or whether it was already present in the population 100 years ago,” Booth said.
The next step will be to expand the search to detect these mutations worldwide, especially in Europe, and in museum exhibits from different periods, as bed bugs have been around for over a million years.
In November 2024, Booth Labs became the first laboratory to successfully sequence the entire genome of the common bed bug.
”This is the first time the genome of this insect has been sequenced,” Booth said. “Now that we have the genome sequence, we can study these museum specimens.”
Booth notes that the problem with museum DNA is that it breaks down into small fragments very quickly, but researchers now have chromosome-level templates that allow them to extract these fragments and align them with these chromosomes to reconstruct genes and genomes.
Booth notes that his lab collaborates with pest control companies, so their gene sequencing work could help them better understand the global spread of bed bugs and ways to eradicate them.
Now that Brock has honed her skills in molecular biology, she is excited to continue her research into urban evolution.
”I love evolution. I find it very interesting,” Block said. “People feel a great connection to these urban species, and I think it’s easier to get people interested in bed bugs because they’ve probably encountered them firsthand.”
Lindsay Myers is a postdoctoral research fellow in the Department of Entomology and another member of Booth’s research group at Virginia Tech.
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Post time: Dec-12-2025