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Most people hope to never put their eyes on a bedbug. However, a team of researchers has spent 15 years researching specimens of bedbugs in guano-filled caves, nests at the edge of the cliffs and museum archives likely to clarify the troubled natural history of this parasite worldwide. hated.
The team's findings, published Thursday in Current Biology, confirm that bedbugs appeared at least 100 million years ago, when dinosaurs roamed the Earth. The discovery goes against the established chronology of bedbug evolution and could help anticipate the next actions of the pest in the era of climate change and the multiplication of human activities.
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The research team also found that the main varieties of human-related bedbugs had evolved 47 million years ago. As they are tens of millions of years older than humans, their origins should not be related to the emergence of Homo sapiens, as suggested by previous studies.
To reconstruct the complex evolutionary history of bedbugs – a family of insects known as Cimicidae – the team analyzed the DNA of 34 species from 62 sites.
In addition to asking specimens from hundreds of researchers, the authors of the study personally collected bed bugs from around the world. In Texas, the team braved bat stools to their knees, donning masks when the carbon dioxide concentration became too high. In a Kenyan cave, they took care to avoid contamination by the deadly Marburg virus, which can be transmitted to humans by bats.
"The caves are still a bit of an adventure," said Klaus Reinhardt, bed bug expert at the University of Dresden in Germany and one of the leaders in the study.
Information about bed bugs came from other surprising sources, such as Hopi Folklore. "They have a pretty strong cultural heritage related to bed bugs," especially with a species that infests eagles and other birds, Dr. Reinhardt said. "The Hopi had to have a lot of contacts with this bug, otherwise they would not have several stories about it."
The team's efforts, which began in 2002, resulted in a sprawling family tree of Cimicidae whose roots date back to the deepest Cretaceous period. Their data corroborate the fossil evidence of an ancestor of the bedbug, Quasicimex eilapinastes, preserved in 100 million year old amber, identified for the first time by Michael Engel, entomologist of the University of Kansas, in 2008.
"The fossil was the first direct evidence that the family Cimicidae was anterior to the origin of bats," said Dr. Engel, who did not participate in the new study.
Bats have long been presumed to have been the first hosts of bed bugs. It is now clear that the parasites were maintained at the age of dinosaurs by older animals. But the identity of the previous host, or hosts, remains a tempting mystery, as fossil evidence is scarce, said Dr. Reinhardt.
Beyond this glimpse of the distant past of bed bugs, the team explained how the pests seized the parasitic opportunities that eventually led them into our beds.
While most bedbugs specialize in a single host species, human-related lineages are generalists who seek new hosts while retaining the ability to return to old favorites. Even though bed bugs are infested by humans, we are for them a little job. This fact could prove useful for predicting creatures that could colonize our homes, our beds and our bodies.
"In order to be able to predict the next species that will jump on humans, we will have to look at the species that were originally specialists, but who then began to expand their portfolio of hosts," he said. said Dr. Reinhardt.
Such predictions could help prevent or contain new outbreaks of bed bugs during times of climate change and increased mobility.
Wild animals migrate beyond their range due to rising global temperatures, while domestic animals are marketed and shipped to new locations and ecosystems. If these animals carry other species of bed bugs, the pests "will suddenly encounter animals that they have never seen before," Dr. Reinhardt said.
So sleep well and agree that bedbugs continue to bite. They have been sucking blood since T. rex and triceratops traveled the world, and they will not give up this habit anytime soon.
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