Bedbugs are blood-sucking parasites in the family Cimicidae. A multinational research team led by University of Sheffield, the University Museum Bergen and Dresden University has compared the DNA of dozens of bedbug species and discovered that bedbugs are 50 million years older than bats — a mammal that scientists had previously believed to be their first host 50-65 million years ago.
“To think that the pests that live in our beds today evolved more than 100 million years ago (Cretaceous period) and were walking the Earth side by side with dinosaurs, was a revelation,” said University of Sheffield’s Professor Mike Siva-Jothy, co-author of the study.
“It shows that the evolutionary history of bed bugs is far more complex than we previously thought.”
Professor Siva-Jothy and colleagues spent 15 years collecting samples from wild sites and museums around the world, dodging bats and buffaloes in African caves infected with Ebola and climbing cliffs to collect from bird nests in South East Asia.
“The first big surprise we found was that bedbugs are much older than bats, which everyone assumed to be their first host,” said co-lead author Dr. Steffen Roth, a researcher at the University Museum Bergen.
“It was also unexpected to see that evolutionary older bedbugs were already specialized on a single host type, even though we don’t know what the host was at the time when T. rex walked the Earth.”
The scientists found that a new species of bedbug conquers humans about every half a million years: moreover that when bedbugs changed hosts, they didn’t always become specialized on that new host and maintained the ability to jump back to their original host.
This demonstrates that while some bedbugs become specialized, some remain generalists, jumping from host to host.
“These species are the ones we can reasonably expect to be the next ones drinking our blood, and it may not even take half a million years, given that many more humans, livestock and pets that live on earth now provide lots more opportunities,” said co-lead author Professor Klaus Reinhardt, a bedbug researcher at Dresden University.
The team also found that the two major bedbug pests of humans — the common bedbug (Cimex lectularius) and the tropical bedbug (Cimex hemipterus) — diverged approximately 47 million years ago and are much older than humans.
This finding clearly rejects so-called Ashford’s hypothesis, which predicts a divergence that coincides with the split between Homo sapiens and Homo erectus lineages around 1.6 million years ago.
“The findings will help us better understand how bedbugs evolved the traits that make them effective pests — that will also help us find new ways of controlling them,” Professor Siva-Jothy said.
The results were published online this week in the journal Current Biology.
Steffen Roth et al. Bedbugs evolved before their bat hosts and did not co-speciate with ancient humans. Current Biology, published online May 16, 2019; doi: 10.1016/j.cub.2019.04.048