Since some entrepreneurial bedbugs came out of a bat and joined a Neanderthal who left a cave 60,000 years ago, bed bugs have enjoyed a prosperous relationship with their human hosts.
It is not so for the little adventurous bed bugs that stayed with the bats: their populations have continued to decrease since the last glacial maximum, also known as the ice age, which was about 20,000 years ago.
A team led by two technological researchers in Virginia recently compared the entire genome sequence of these two genetically different lineages of bed bug. Posted in Biology letters On Tuesday, May 28, its findings indicate that the lineage associated with humans followed a demographic pattern similar to that of humans and can be the first true urban plague.
“We wanted to analyze the changes in the effective size of the population, which is the number of reproductive people who contribute to the next generation, because that can tell him what has been happening in his past,” said Lindsay Miles, principal author and postdoctoral scholarship in the department of Entomology.
According to researchers, the historical and evolutionary symbiotic relationship between humans and bedbugs will report models that predict the spread of pests and diseases under the expansion of the urban population.
By directly linking human global expansion to the appearance and evolution of urban pests such as bed bugs, researchers can identify traits that evolved together in both humans and pests during urban expansion.
A staircase graph (on the left) shows that the patterns of the bedside demography genome reflect the global human expansion, courtesy of the Biology Letters 21: 20250061. The image of the bed bugs is courtesy of Warren Booth.
“Initially with both populations, we saw a general decrease that is consistent with the last glacial maximum; the lineage associated with the bat never recovered, and is still decreasing in size,” said Miles, an affiliate from Falin Life Sciences Institute. “The really exciting part is that the lineage associated with humans recovered and its effective population increased.”
Miles points to the early establishment of great human settlements that expanded to cities like Mesopotamia about 12,000 years ago.
“That makes sense because modern humans moved from the caves about 60,000 years ago,” said Warren Booth, an associate professor of urban entomology at Joseph R. and Mary W. Wilson. “There were bedbugs who lived in the caves with these humans, and when they moved they took a subset of the population with them, so there is less genetic diversity in that lineage associated with humans.”
As humans increased the size of their population and continued to live in expanded communities and cities, the lineage associated with the humans of the bedbugs saw an exponential growth in their effective population size.
By using complete genome data, researchers now have a basis for a subsequent study of this 245,000 year old lineage division. Since the two lineages have genetic differences but not enough to have evolved in two different species, researchers are interested in focusing on the evolutionary alterations of the lineage associated with humans compared to the lineage associated with BAT that have been carried out more recently.
“What will be interesting is to look at what is happening in the last 100 to 120 years,” said Booth. “Bunts were quite common in the old world, but once DDT [dichloro-diphenyl-trichloroethane] It was introduced for pest control, the populations crashed. It was thought that they were essentially eradicated, but in five years they began to reappear and resisted pesticide. “
Booth, Miles and the graduated student Camille Block have already discovered a genetic mutation that could contribute to that resistance of insecticides in a previous study, and are considering even more the genomic evolution of bed bugs and the relevance for the resistance to the insecticides of the plague.
Booth said the project is a good example of what happens when researchers “follow science”, which give it the space to do thanks in part to the endowment of Joseph R. and Mary W. Wilson that supports the position of their faculty.
“It’s a great resource to have,” said Booth. “We are using it for the work that investigates the evolution of the resistance to insecticides and the spread of species using museum samples collected from 120 years ago to our current samples.” I am very lucky to have that freedom to explore. “