Bed bugs boom tracked using DNA fingerprinting

Bed bugs in the crevice of a sofa The bugs hide in any available crevice in household furniture and are extremely difficult to eradicate

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Biologist Toby Fountain is fascinated by bed bugs.

He was originally intrigued by their "traumatic" reproductive behaviour; males injecting sperm directly into females' abdomens.

But Toby is now leading a study to find out why the infamous insects have spread so much in the last decade.

He and his colleagues are using DNA fingerprinting techniques in an effort to track down the origin of the great bed bug boom.

He discussed his project at the First Joint Congress for Evolutionary Biology in Ottawa.

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The global surge in bed bugs, Toby explained, was first documented just after the 2000 Sydney Olympics.

"It's been getting more and more prevalent since then," says the scientist.

The cost of the spread has been exorbitant, although the exact figure is difficult to estimate, it has been placed in the tens of millions.

Primarily, this cost comes from law suits against hotels that are accused of being infested and leaving their guests badly bitten.

Other law suits have been taken out against pest controllers who, if and when a bed bug infestation returns, are accused by customers of failing to do their job properly.

This is where the University of Sheffield study could ultimately settle some expensive arguments.

Tracking 'pests'

The team's genetic techniques are pinpointing "signatures" in a bed bug's DNA that reveal which particular infestation a bug has come from.

Close up of a bed bug The wingless insects "hitch a ride" in people's clothing and baggage

"If you've picked up bed bugs from a hotel, you could look at the genetic markers of that bed bug and be fairly sure that they came from that place," Toby explains.

"And if every pest controller keeps a [sample and a] record of any infestation, we'll eventually be able find out whether any repeat infestations came from the same place, and whether that pest controller has done his job properly."

Currently, this prospective bed bug tracing tool is in the very early stages of development.

Toby is still in the process of gathering his bug DNA evidence, joining pest control teams across London to gather samples and trace the spread of the insects around the capital.

He says London is a "bed bug hotspot" and the psychological trauma the bugs cause is palpable.

"People in infested properties get extremely distressed," he explains.

There is even a condition, known as delusory parasitosis, in which people can actually break out in a bite-like rash, apparently caused by the stress of worrying about bed bugs.

"I've been to places in London and you can see it spreading through entire council blocks.

Bed bug bites on a human hand They are voracious blood-suckers, and one human can provide for an almost unlimited number of bugs

"The effect it has on people is terrible.

"I didn't realise how bad it could be until I went into some of these properties," Toby says.

Toby showed images of bed bugs, taken during his pest control trips, which revealed hundreds or even thousands of bugs crowded into crevices between sofa cushions.

He recalls one man in particular, in a badly infested London council flat.

"He sat in one chair and the bed bugs were all living in the other chair, so they would emerge in a line, walk over to his chair, feed on him and then go back home."

Hitching on humans

Despite all the discomfort, cost and upset they cause, Toby is clearly quite impressed by the sheer hardiness and capabilities of the bugs.

The fact that they have been able to spread throughout the globe in such a short time is remarkable.

The blood-sucking insects cannot fly and, since a single human can provide essentially an unlimited amount of food for a colony, finding a new home does not make much sense for their survival.

Leaving the comfort of their sofa crevice is actually quite risky. But it seems that bed bugs instinctively search for new places to hide and reproduce.

Toby Fountain did not believe how bad infestations could be until he witnessed it for himself.

"They have this horrible little habit of sneaking into your clothes or your bags whenever you stay at an affected property.

Bed bugs living in the crevice of a sofa Toby Fountain did not believe how bad infestations could be until he witnessed it himself

"So that means that the next time you step on a train or a plane they can suddenly move thousands of miles in one go.

"And this is quite a new thing, because it's only fairly recently that global air travel has become accessible to the general public."

This could explain the link between an Olympic year and a bed bug boom.

The genetic techniques Toby is using are just starting to get to the core of how global travel affects bed bug biology; how they are mutating, adapting and surviving.

One thing he has discovered is that they seem to be untroubled by the genetic effects of inbreeding, so they can just keep reproducing within their colonies.

To solve the mystery of bed bugs' worldwide success, Toby and his colleagues are now starting to work outside of the UK, primarily in Kenya, taking samples from homes in towns around Nairobi, and some smaller villages.

"In Kenya, bed bugs have always been there. So one theory is that that's where [the UK's bug resurgence] came from," explains Toby.

"Another theory is that they've always been in the UK, but in little, tiny pockets, and for some reason they've exploded out of these pockets in the last 10 years."

If Toby and his team find a genetic link between Kenya's bed bugs and those of the UK, they might be able to solve that part of the puzzle once and for all.

"I think we're getting closer," the scientist says.

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