Bed Bugs Are Most Likely the First Human Pest, New Research Shows

taylorvich writes:

https://phys.org/news/2025-05-bed-bugs-human-pest.html

Ever since a few enterprising bed bugs hopped off a bat and attached themselves to a Neanderthal walking out of a cave 60,000 years ago, bed bugs have enjoyed a thriving relationship with their human hosts.

Not so for the unadventurous bed bugs that stayed with the bats-their populations have continued to decline since the Last Glacial Maximum, also known as the ice age, which was about 20,000 years ago.

A team led by two Virginia Tech researchers recently compared the whole genome sequence of these two genetically distinct lineages of bed bugs. Published in Biology Letters, their findings indicate the human-associated lineage followed a similar demographic pattern as humans and may well be the first true urban pest.

"We wanted to look at changes in effective population size, which is the number of breeding individuals that are contributing to the next generation, because that can tell you what's been happening in their past," said Lindsay Miles, lead author and postdoctoral fellow in the Department of Entomology.

According to the researchers, the historical and evolutionary symbiotic relationship between humans and bed bugs will inform models that predict the spread of pests and diseases under urban population expansion.

By directly tying human global expansion to the emergence and evolution of urban pests like bed bugs, researchers may identify the traits that co-evolved in both humans and pests during urban expansion.

"Initially with both populations, we saw a general decline that is consistent with the Last Glacial Maximum; the bat-associated lineage never bounced back, and it is still decreasing in size," said Miles, an affiliate with the Fralin Life Sciences Institute. "The really exciting part is that the human-associated lineage did recover and their effective population increased."

Miles points to the early establishment of large human settlements that expanded into cities such as Mesopotamia about 12,000 years ago.
"That makes sense because modern humans moved out of caves about 60,000 years ago," said Warren Booth, the Joseph R. and Mary W. Wilson Urban Entomology Associate Professor.

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