Study finds bed bugs may be genetically re-wiring to resist insecticides
Researchers have found a gene mutation in bed bugs that mirrors one known to cause insecticide resistance in German cockroaches and whiteflies.
Bed bugs appear to have developed a genetic resistance to some insecticides designed to kill them, according to a recent study published in the Journal of Medical Entomology. It's an evolution that may have been decades in the making, triggered by early attempts to curb bed bug population booms.
A history of infestation and control
In the 1950s, increasing international travel and immigration helped fuel a global bed bug infestation. In the U.S. alone, as many as 30 per cent of houses were infested.
The problem was successfully controlled with dichloro-diphenyl-trichloroethane, or DDT. However, by the 1970s, manufacturers phased out DDT usage due to associated environmental and health concerns. Today, DDT is banned for most uses worldwide.
The bed bugs plot their return
In the recent paper, the authors argue that since DDT has been banned, bed bugs have steadily re-gained ground globally and display “resistance to an array of insecticides used for their control.”
The study, led by Virginia Tech urban entomologist Warren Booth and graduate student Camille Block, identifies a gene mutation in bed bugs that mirrors one known to cause insecticide resistance in German cockroaches and whiteflies.
Tracing the mutation
Using data from North American pest control collections from 2008 to 2022, Block analyzed a bed bug from each of 134 distinct populations. Two samples from different locations presented the nerve cell mutation observed in other insecticide-resistant insects.
Because bed bug populations are typically highly inbred, one individual is generally a fair representation of its entire infestation. But to be sure, the team screened all specimens from the two affected populations.
“When we went back and screened multiple individuals from the two populations, every one of them had the mutations,” Booth said in a statement.
“So they were fixed for these mutations, and it’s the same mutation that we find in German cockroaches.”
The role of Rdl
The mutated gene is known as Rdl, and it has been documented in several pest species. It is associated with dieldrin, a chemical belonging to the same group of organochlorines as DDT. Dieldrin was banned in the 1990s, but Fipronil—an insecticide with the same mechanism of action—is still in use today.
According to the study’s authors, because Fipronil shares this mechanism, the gene mutation should, in theory, allow bed bugs to gain resistance to both pesticides. Fipronil is typically used as a flea treatment for cats and dogs and has been proven effective against bed bugs in lab tests, alongside the now-banned dieldrin.
Booth suspects the way some pet owners interact with their animals may be driving this mutation.
“Many pet owners let their dogs or cats sleep in bed with them,” he said.
“If those animals have been treated with Fipronil, it could leave residue in the bedding, inadvertently exposing any bed bugs present and selecting for this mutation.”
Booth says the next step is to expand upon the findings and search for the gene mutation in bed bugs in other parts of the world, as well as in different eras. That includes museum specimens—because bed bugs have scurried about Earth for millions of years.
Bed bugs and the weather
Sandy Smith, a forestry professor at the University of Toronto, told The Weather Network in 2023 bed bugs will always be near humans because they need our blood to survive.
"Like all organisms, in all insects, they have an optimal range. Our household temperatures are about right for them," she said.
Adult bedbugs usually live around ten months, though they can extend their longevity to a year or even more inside a hospitable home with temperatures between 21°C and 28°C.
Bed bugs can tolerate the cold, but if exposed to below-freezing temperatures for several days, they will die.
"We're blessed in Canada with a really cold winter," Sandy said, adding that putting your mattress outside for five days during a cold spell will kill them.
They don't do well in warmer temperatures, which can cause them to become dehydrated.
Bed bug FAQ
How do bed bugs get into my home? Bed bugs are master hitchhikers. They can enter your home through clothing or backpacks, luggage, or purses placed on upholstered surfaces. They can also come into the home through infected furniture, according to the New York Department of Health.
How do I reduce the risk of bringing bedbugs home? Keep your bags or suitcases on stands when at hotels. When you return home, wash your clothes and place them in a hot dryer.
How do I confirm a bed bug infestation? You can see the bugs. You may also visit their droppings, eggs, or shed skin on your living spaces.
What do I do if I have bed bugs? Contact a reputable specialist with a proven track record of successful bedbug removal. Bed bug infestations can be challenging to eradicate, and professional assistance is often necessary for adequate control.
*Header image credit: Piotr Naskrecki. File photo via Wikimedia, public domain. *
