They call the nighttime home. They’re bloodsuckers. And their ancient relationship with humans can be charted back some 3,000 years.
During World War II, their numbers dwindled, as chemical usage increased in economically and politically stable countries. But small populations waited in the wings, feeding on bats, chickens, and other animals; biding their time.
Then, something happened. As international travel became a norm, they hitched rides around the world. In the last 20 years, their numbers have grown significantly, as has their resistance to insecticides.
Some of the aforementioned descriptions may sound like they’re about vampires, but they’re actually about pesky bed bugs. And the world’s got a problem. These things are everywhere. Save for Antarctica, bed bugs have laid claim to every continent. In Australia, infestations have increased by 4,500%, and in the U.S., no state is untouched.
A team of international researchers recently sequenced the genome of the common bed bug Cimex lectularius, illuminating the genetics that may be responsible for their increased resistance.
“Resistance can result from multiple mechanisms that include target-site mutations, differential gene expression, alterations in the permeability of the cuticle or digestive tract and behavioral changes,” the researchers write in Nature Communications. “Transcriptomic evidence supports the presences of multiple resistance mechanisms in bed bug populations.”
Among the findings, the researchers report that mutations in sodium channel genes have resulted in a high percentage of pyrethroid—an insecticide—resistance in U.S. and European bed bug populations.
“Resistance to insecticides has become widespread and pyrethroid resistance has reached levels 10,000-fold higher than in susceptible bed bug populations,” the researchers write.
Additionally, the researchers found the studied bed bugs significantly reduced their chemosensory genes, and expanded their genes associated with blood digestion.
Further complicating the issue is the fact that bed bugs can go months without a blood meal, which is their main source of nutrition and water.
“The sequencing, assembly, annotation and manual analyses of the C. lectularius genome provide an important and timely resource for understanding the biology of this human ectoparasite,” the researchers write. “It also will serve as a gateway for the discovery of new targets for control of bed bug populations.”