Genome secrets of the bedbug may help you sleep tight

February 03, 2016

Have you ever checked into a questionable motel room where the threat of bedbugs leaves you tossing and turning all night? Well, thanks to a group of scientists who have successfully decoded the insect’s DNA, there may be new ways to exterminate the blood-sucking parasite, and in turn, help you to rest peacefully.

The results may also help researchers map bedbug (Cimex lectularius) activity across entire cities, simply by analyzing the DNA the bugs leave behind in public places, such as subway stations, the researchers said in a recent article.

"Bedbugs are one of New York City's most iconic living fossils, along with cockroaches, meaning that their outward appearance has hardly changed throughout their long lineage," study co-author George Amato, said in the article. "But despite their static look, we know that they continue to evolve, mostly in ways that make it harder for humans to dissociate with them."

Bedbugs have fed on the blood of humans for at least 3,000 years. But there's been a recent uptick in infestations, especially in urban areas, with the advent of heated homes and global air travel. Moreover, it's thought that bedbugs have developed resistance to certain pesticides, which may explain the insects' resurgence in the 1990s.

"Bedbugs all but vanished from human lives in the 1940s because of the widespread use of [the insecticide] DDT, but, unfortunately, overuse contributed to resistance issues quite soon after that, in bedbugs and other insect pests," study co-author Louis Sorkin said in the article. "Today, a very high percentage of bedbugs have genetic mutations that make them resistant to the insecticides that were commonly used to battle these urban pests."

However, in this new study, researchers are working on understanding the bedbug's basic biology and figure out how to kill them.

For instance, the researchers found that the bedbug's gene expression changes after the pest slurps up its first blood meal. Some of these genes code for optimal methods to detoxify and for growing thicker skin, among other features for insecticide resistance. So, perhaps the best time to target bedbugs is during the first nymph stage (there are five total nymph stages), before the bug takes its first blood meal, the researchers explained.

To decode the bug's genome, DNA and RNA from both preserved and living collections were examined. The scientists also collected RNA samples from males and females during the bedbug's different life stages to see how gene expression — for example, expression related to blood feeding, insecticide resistance and other vital functions — changed over time.

The article explains that the researchers also studied the bedbug's bacteria, or microbiome. In all, the microbiome contained more than 400 bacterial species, with more than 1,500 genes, suggesting that these bacteria are essential for the bug's growth and reproduction. Perhaps antibiotics that target these bacteria could complement other methods of insect control, the researchers noted.

After analyzing the bug's genome, the researchers canvassed New York City, looking for evidence of different bedbug communities. The scientists looked at more than 1,400 locations across the city, including every subway station.

Intriguingly (and disturbingly), the scientists found the city is blooming with bedbug diversity. Bedbug genetic makeup differs widely in different parts of the city, with distinct populations in different boroughs. Researchers said they hope to continue the search, which may help them map bedbug-migration patterns in new environments.

In the other study, researchers found 187 potential genes that encode blood-digesting enzymes, along with an array of salivary proteins that help bedbugs feed on people without causing pain. The scientists also identified genes associated with insecticide resistance, including those that encode enzymes that can detoxify insecticides.

The scientists involved in these two studies are now collaborating to map the mitochondrial DNA (genetic data passed down by females) in bedbugs and will also put together a map to understand the relatedness of different populations.

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Category: Genomics