Aarian Marshall is a transportation reporter at WIRED and former CityLab contributor. She lives in San Francisco.
Go out and hug a scientist: They’ve sequenced our enemy’s genome.
In an all-too-rare win for humanity, a team of researchers from the American Museum of Natural History and Weill Cornell Medicine have sequenced the bedbug genome. It is the first step, they say, in finding the chinks in the armor of these little, sneaky bloodsuckers, and insecticide-ing them into eternity.
Bedbugs are miraculously hardy little beings, says Chris Mason, a geneticist at Weill Cornell and senior author on the research published this week in the journal Nature Communications. They’ve gone pretty unchanged for thousands of years or so, making them what scientists sometimes call “living fossils” (though researchers don’t quite have enough ancient bedbug DNA to confirm the moniker, Mason says). And as the research demonstrated, bedbugs have developed an unusually strong resistance to modern pesticides. “This makes the control of bedbugs extremely labor intensive,” the AMNH invertebrate specialist Louis Sorkin said in the understatement of this fresh, new year.
By sequencing bedbugs’ genome, however, scientists were able to discover a few unusual bedbug properties—ones that could point toward new and, Lord willing, devastatingly effective killing strategies. The first is the radical change in gene expression that occurs just after a bedbug has had a blood meal, or chowed down on your naked and vulnerable skin.
When any organism is growing and developing, different genes are expressed in different ways, Mason explains—that’s why a 10-year-old boy looks and smells different than the same boy when he becomes a 16-year-old teenager, and why a 16-year-old female teenager looks different from a similarly aged male. But there is more variation in gene expression in bedbugs before and after a blood meal than there is between male and female bedbugs. Put more simply: crazy stuff happens in bedbugs’ bodies when they’re engorged with human blood.
For the bug-fearing city dweller, this is the vital part: That post-meal gene expression is linked to insecticide resistance. This suggests that a more effective bedbug insecticide would target bedbugs when they’re babies, or “nymphs”—before they’ve had literally life-altering blood meals.
The second big discovery is delightfully New York-specific: Just like your friend who refuses to come to Brooklyn on the weekends, the researchers discovered that bedbugs are loath to leave their respective boroughs. The scientists used DNA data collected from 1,447 locations—including 465 subway stations, every gosh darn one in the system—to analyze the genomic profiles of different populations of bedbugs. Don’t freak out: This does not mean, Mason emphasized, that scientists went out and found a bedbug in every subway station. Rather, they used DNA swabs, many already taken for a well-publicized 2015 study on the microbiome of the subway, and analyzed them for traces of bedbug DNA.
In the end, the scientists discovered that bedbug populations differ, genetically, by borough, though north-south populations—Brooklyn and Queens, for example—are more related than east-west ones—Queens and Manhattan. Eventually, Mason says, scientists may be able to look at your couch’s bedbug infestation and know from “the differences in bedbugs themselves—their different cuticle genes, their effectively different resistance from antibiotics or insecticides—where [they] came from in the city.” One day, researchers may be able to use these clues about bedbug “migration” to trace infestations and stamp them out.
Sequencing the genome is only a small step, says Mason, but he and his team of researchers will continue to collaborate with others to learn more about the bedbug. That includes a group of scientists from the i5K Project, which hopes to sequence the genome of 5,000 insect species and just happened to publish a similar paper on the bedbug genome in the same journal on the same day as the AMNH/Weill Cornell team.
And if you doubt these scientists’ dedication to the bedbug cause, consider the tale of Sorkin, the AMNH specialist, who has been raising the population of bedbugs used in this study since the early 1970s. “I feed them about once a month,” he told the New York Times in 2009. “I invert the jars on my arm and the bugs feed through the screening. It doesn’t hurt. The swelling goes down in an hour or two.”