PHILADELPHIA—When you have bedbugs (Cimex lectularius), less interesting is the question of how they got there than the conundrum of how best to get them out. Ridding homes and businesses of these pests has become a multimillion dollar industry in many cities in the U.S. and throughout the world.

A few scientists, however, are now asking just how these populations have been spreading from town to town and from headboard to headboard. Answering that question might lead to better ways of controlling their spread into the future.

Researchers are using genetics to try to trace bedbug lineages in the U.S. as well as those in individual apartment buildings. "It's actually kind of a forensics question," Coby Schal, an entomologist at North Carolina State University in Raleigh, said at the American Society of Tropical Medicine and Hygiene's annual meeting in Philadelphia on Tuesday.

Schal and others have analyzed bugs collected up and down the U.S. east coast—and across the country to see whether the vermin have emerged from a few foreign entries, from local animal populations or whether they are repeatedly imported from abroad and then spread throughout the country. In more finite searches of regional apartment buildings, the researchers also found some dark secrets about bedbug pairing practices that help to explain how they can infest an area so quickly.

Crying fowl
Bedbugs have a cozy history with humans; there is evidence they plagued ancient Egyptians some 3,500 years ago. And now, with so many people living in cities across the globe, "we've created the perfect habitat," Rajeev Vaidyanathan, associate director of vector biology and zoonotic disease at the research institute SRI International, said here Tuesday.

But humans are not the only animals on whose blood bedbugs feast—they seem to have a taste for chickens' as well, Vaidyanathan noted. And we have conveniently created massive poultry operations in which the bugs can thrive. In fact, "you can collect them by the bucket off the walls of a poultry house," he says. Because of this, some scientists have argued that these reservoirs of bugs might be to blame for their reemergence.

In a poultry house, however, a bedbug would not be exposed to the same insecticides as one living among humans. Further, the insects rapidly develop resistance to common pesticides, so the prevalence of insecticide-resistant bedbugs in homes suggests that the bugs have not simply come crawling in from the henhouse, Schal pointed out. The populations are more likely to have come from farther afield.

Global hitchhikers
Even before bedbugs made their resurgence in the U.S., they were already biting many more people in Australia and Canada. And they have been a persistent problem in other, less developed countries.

If the bugs arrived from just a few travelers several years ago and had mostly been spreading in the U.S. since then, containment efforts might have been more effective than if they were recurrently entering the country.

A genetic survey across the U.S. found that among towns, bedbugs have great genetic variation. That diversity suggests that, rather than having been brought into the country only a few times, the parasites crossed the borders many times—and are likely continuing to do so. These founder bugs go on to create larger populations. Even in well-connected and highly populated cities on the Interstate 95 corridor along the east coast, bedbug populations remained relatively distinct from one another.

7 Comments

1. 1. Wulfrano Ruiz Sainz 01:15 AM 12/8/11

   Bedbugs are horrid creatures, worse than roaches. Women, out of primeval fear, scream at roaches, but are unmoved by bedbugs. This feminine reaction doesn't make sense because roaches don't suck your blood while bedbugs do.

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2. 2. ASHIK 10:36 AM 12/8/11

   Growing bed bugs in poultry farm does not make sense.They are so tiny and diverse that it is difficult to make out whether any of distinct species goes extinct or not.

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3. 3. Wulfrano Ruiz Sainz 01:21 AM 12/9/11

   The bedbugs I'm worried about are those which infest the Vatican.

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4. 4. genny 06:15 AM 12/14/11

   Take it easy! If you are lucky to see one or more bedbugs, without hesitation, just raise your one of feet and then step them on!!!!

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5. 5. Wulfrano Ruiz Sainz 01:45 AM 12/15/11

   When I was in Mexico City a bedbug sucked my blood. On the following morning I was sore, swollen and itchy. Then I saw it! It was so full of my blood that instead of staying flat it was round like a dark-red-brownish marble.

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6. 6. bucketofsquid 05:32 PM 1/4/12

   From what I've read the best way to combat bedbugs isn't pesticides. It is better to do a floor to ceiling cleaning and launder everything. If I remember correctly you also need to replace your matress and clean or replace any couch or chair cusions too.

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7. 7. Wulfrano Ruiz Sainz 01:26 AM 1/5/12

   Sorry for my mistake. I clicked on the wrong key. Anyway, what I want to say is that bedbugs remind me of certain in-laws of mine who do not work but come over to my house just to freeload at the expense of my wife's stupid... oops!... sorry... at the expense of her good-hearted generosity.

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