Why Are Bed Bugs So Hard To Kill? Scientists Uncover Genetic Survival Secrets

SciTechDaily ^ | December 28, 2024 | Hiroshima University

[george76]

Scientists mapped genomes of bed bug strains, identifying 729 mutations linked to insecticide resistance, offering insights for improved pest control.

Scientists have successfully mapped near-complete and highly accurate genomes for two strains of bed bugs: one highly susceptible to insecticides and another “superstrain” that is roughly 20,000 times more resistant. This achievement provides the most comprehensive view yet of the genetic mutations behind insecticide resistance. The findings were published in the journal Insects.

While bed bugs are not known to transmit diseases to humans, their bites can cause itchy rashes and secondary infections. Insecticide use, including the now-banned DDT, nearly eradicated bed bug populations by the 1960s, making infestations a rarity. However, over the past two decades, bed bugs have made a global resurgence, largely due to genetic mutations that have rendered them resistant to modern insecticides.

Resistance can develop through various mechanisms, such as producing detoxifying enzymes (metabolic resistance) or evolving thicker protective outer layers that block chemicals (penetration resistance). Previous studies have identified some of the genes and mutations involved in resistance, but the complete genetic picture remained unclear because no prior research had sequenced the entire genomes of resistant strains. This new study fills critical gaps, shedding light on the full spectrum of mutations driving their resilience.

..

A research team led by Hidemasa Bono, professor at Hiroshima University’s (HU) Graduate School of Integrated Sciences for Life, mapped genomes of susceptible and resistant bed bug strains from Japan to address this gap. They obtained susceptible strains descended from wild bed bugs (Cimex lectularius) collected 68 years ago in fields at Isahaya City, Nagasaki. Meanwhile, the resistant strains were bred from specimens collected from a Hiroshima City hotel in 2010. Their tests revealed that the resistant samples had 19,859-fold stronger resistance to pyrethroids — the most commonly used insecticide for bed bug control — exceeding levels seen in many previously identified superstrains. All the specimens were provided by Fumakilla Limited, a Japan-based chemical manufacturing company.

Piecing together the genome puzzle..

Sequencing a genome is like assembling a massive jigsaw puzzle, spanning anywhere from about 160,000 to 160 billion pieces. To map the most complete bed bug genomes to date, researchers used the breakthrough method of long-read sequencing, which captures longer stretches of DNA—akin to having entire sections of puzzle pieces put together. Traditional short-read sequencing, by contrast, only covers tiny snippets, often leading to frustrating gaps.

The researchers assembled a near-total picture of the two genomes with just about every piece precisely where it belonged, achieving 97.8% completeness and quality value (QV) of 57.0 for the susceptible strain and 94.9% completeness and QV of 56.9 for the resistant strain. A QV above 30 indicates high-quality sequences with less than 0.1% error rate. Both also surpassed the N50 value of the existing C. lectularius reference genome, Clec2.1, from a previous sequencing effort, meaning there were fewer gaps and more complete sections of the genome puzzle.

Known, new resistance mutations uncovered..

After fully sequencing the genomes, the team identified protein-coding genes, determined their functions, and assessed if they were active through transcriptional analysis. They uncovered 3,938 transcripts with amino acid mismatches. Of these, 729 mutated transcripts were linked to insecticide resistance.

“We determined the genome sequence of insecticide-resistant bed bugs, which exhibited 20,000-fold greater resistance compared to susceptible bed bugs. By comparing the amino acid sequences between the susceptible and resistant bed bugs, we identified 729 transcripts with resistance-specific mutations,” said study first author Kouhei Toga, postdoctoral researcher at the Laboratory of Genome Informatics of HU’s Graduate School of Integrated Sciences for Life.

“These transcripts included genes related to DNA damage response, cell cycle regulation, insulin metabolism, and lysosome functions. This suggests that these molecular pathways may play a role in the development of pyrethroid resistance in bed bugs.”

By drawing on previous insect studies, the researchers confirmed known resistance mutations and discovered new ones that could inform more targeted and effective pest control strategies.

“We identified a large number of genes likely involved in insecticide resistance, many of which have not been previously reported as being associated with resistance in bedbugs. Genome editing of these genes could provide valuable insights into the evolution and mechanisms of insecticide resistance,” Toga said.

“Additionally, this study expands the pool of target genes for monitoring allele distribution and frequency changes, which could contribute significantly to assessing resistance levels in wild populations. This work highlights the potential of genome-wide approaches in understanding insecticide resistance in bed bugs.”

[Delta 21]

A huge gigantic story outlining herculean efforts to irradicate bed bugs. And we still have bedbugs.

[TiGuy22]

Can they been seen? I’ve heard they’re as large as an apple seed, so I would assume yes?

[fso301]

I’ve heard they’re as large as an apple seed

Correct but they didn't hatch that size. By the time they are the size of an apple seed, they have been breeding and the dark appleseed color means they are full of someone's blood.

We never tried the diatomacheous earth. Montag813 reports good results using diatomaceous earth for their infestations. I considered it for our infestation but due to the widespread nature of our infestation, I opted for "do it yourself heat treatment".

To me, the juvenile bugs are the greater problem than the mature, easier to detect appleseed sized ones. The juvenile bugs are tiny like a grain of sand and can be difficult to detect. They may get on you while you are sitting on the couch. Then, when you get up from the couch, go into the bedroom, sit on the bed to take your shoes off they may hop off onto the bed. In this scenario, any traps the bed posts are sitting in will have been of no effect as the bed became (re)infested via human carrier.

For local treatment of items like mattresses and box springs, 70 percent rubbing alcohol kills them on contact. Use the $5 "pro grade" spray bottle from Home Depot. The $3 standard grade spray bottles don't last long with the alcohol. Be careful about not getting the alcohol on varnish... we made that mistake.

But heat really gets them. They can survive the washing machine but the 130+ degree temps in the dryer kill them. Summertime temps inside a parked car sitting in the sun can also kill them.

For our house infestation, I got a few portable electric heaters at a local thrift store along with some box fans, ordered about 6 inexpensive wireless thermometers on Amazon. Turned the household HVAC off. Unplugged electronic devices in the room being heated. Put the thermometers between mattresses and box springs, inside drawers, inside jacket pockets, on the floor, etc. Turned the heaters and fans on and waited for all thermometers to hit 130F or higher then waited a couple of hours. From time-to-time I went into the room to visually make sure everything was ok, reposition fans and/or thermometers. Repeated the process room, by room. For the larger common areas, I added a kerosene and propane torpedo heater to help get the space up to 130F and higher.

Heat treatment sounds scary at first but 130F-160F temps are far from flammable.

[fso301]

It's also important that everyone in the house understand what bedbugs are, how they spread and follow anti-bedbug protocol.

[Revel]

I believe that they came for south America this time around.

[woodbutcher1963]

Once a year I buy a big bag of DE a put it all around the fenced in yard where we keep the beagles.
DE kill ticks too.

[woodbutcher1963]

I got a few bites on me after staying in a pretty expensive hotel.
My wife who was in the same bed didn’t get any.

I NEVER unpack my luggage at any hotel ever anymore.
I always put the bag on a luggage rack off the floor.

When we got home I left the bags in the garage.
Took all the clothes and immediately into the washer then dryer on high heat.
Then the carry on bags went in the dryer too.
Plus a back pack I had brought went in the dryer.

I also called the hotel and spoke to the manager.

[TiGuy22]

Wow, thank you.

[SunkenCiv]

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• Smithsonian Preserves the World's Ticks [03/24/2003]

[equaviator]

Bedbugs are like the world’s tiniest squatters. You can’t live with them and you can’t kill them.

[SunkenCiv]

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  ---

• Israelites Came To Ancient Japan [03/27/2003]
  (an old topic that just got the refreshed GGG links msg)

[Ruy Dias de Bivar]

Bring back DDT. It worked wonders on bed bugs!

[fso301]

Bedbugs are like the world’s tiniest squatters. You can’t live with them and you can’t kill them.

You can kill them. See my post #23 above.

[MikelTackNailer]

True; even if the owners spray a lot. When I stayed at a long-term motel I learned to bag the mattresses and keep a cup of water on the night table to drown the super ones who overcame that. Despite all that pesticide resistance the bastards drown in less than a minute.

I believe the bed bugs, like previously eradicated diseases, have been spread by illegal aliens.

[equaviator]

I’m okay with being half right.