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While the saying “Sleep tight, don’t let the bed bugs bite” is centuries old, the insects were not common in developed countries mere decades ago. Now, the parasites have infested expensive hotel rooms, college dorms and pristine homes like never before, greeting waking humans with telltale red welts. Looking for progress towards a means of eradicating the pests, two teams of scientists conducted studies that show the genetic makeup of bed bugs and how they have adapted to become a persistent problem.
The common bed bug, Cimex lectularius, has been proliferating for the past two decades. The pest feed on blood from people and animals. The researchers show, by mapping the bed bug’s genome, how the hardy insect adapted and became so resistant to insecticides. Whole genome sequences, which are essentially maps of the particular organism’s DNA, help decipher how it looks, functions and deals with its environment. The eventual goal for this particular effort is to find a way to control the bugs and keep them out of beds in the future.
The bed bug’s genetic makeup shows which genes that help it feed. According to data published in Nature Communications by two independent teams of researchers from 36 institutions, the parasitic bugs have relatively few genes associated with smell and vision to help them from their victims. However, they seem to have no problem finding sources of food. Then, their genes that make salivary proteins allow them to take multiple bites during one feeding (leaving a series of red welts) without the blood clotting. Jeffrey Rosenfeld, a bioinformatics expert at Rutgers University and the American Museum of Natural History who coauthored one of the journal pieces, commented on the bed bug, “It’s a complicated genome. They’re just weird creatures.”
The two teams did not realize they were competing in their bed bugs genetic progress study efforts, which they undertook for different reasons. One team decided to use bed bugs in a project they began in 2012 as well as other urban pests such as the German cockroach and agricultural pests such as the Colorado potato beetle. The second group of scientists chose the bed bug as a pilot for sequencing full genomes at the American Museum of Natural History in New York City. This group opted for bed bugs because they consider them to be a “living fossil.” Given the recent widespread outbreaks, particularly in hotels, they have also become iconic NYC pests.
Initially, the two teams were unaware that they inaugurated similar genome studies. Once they became aware, they realized they were both far along and keep the projects separate.
To put a genome together, scientists take DNA from cells and use machines to analyze its chemical makeup. These two groups took slightly different tacks to sequence the genome.
Employing a traditional approach, one team focused on the genome, aiming to cover it thoroughly. Starting with a computer analysis, they then did some manual annotation. One area they looked at is related to insecticide resistance. Some genes protect the bug’s nervous system, help them detoxify the chemicals, and thicken the bed bug’s exoskeleton to prevent pesticides from penetrating.
The other group of scientists looking to show the pests’ genetic progress also sequenced bed bugs’ genome with fewer manual annotations. They put emphasis in looking at how the bug’s genes function and how the pest interacts with its environment. The team examined the six stages of the insect’s life cycle and noted increased genetic activity after the bug gets its first taste of blood. They also looked at bug DNA gathered in subway stations that showed different strains of bed bugs existed in different regions of the city.
Written and edited by Dyanne Weiss
University of Cincinnati: International genome research partnership uncovers bed bug resistance to pesticides
Newsweek: Map Of Bed Bug Genome Explains Ick Factor And Some Mysteries
Popular Science: The Bugs Behind The Bed Bug Genome
Photo courtesy of U.S. Centers for Disease Control and Prevention (Public Domain)