bed bugs often live in bats, but these flying mammals are not insects' favorites.is more than just a blood-sucking bug that makes visitors suspicious of the size of apple seeds on hotel sheets. About 100 species of bed bugs afflict bats and birds, some of which live deep in caves rarely accessed by humans. Today, scientists use DNA from more than 30 bedbugs to create the first bedbug genealogy, which is full of surprises - for example, the pesky insect is much older than previously thought and dates back to the days of dinosaurs.
Though researchers are not sure exactly which creature became the first "lucky person" to be bitten by a bedbug, they now know that over time, at least three different bugs begin to fall in love with human blood.
recently made progress in detailing the evolutionary history of insects such as elephants, hedgehogs and hunting, said Christiane Weirauch, a systems entomologist at the University of California, Riverside, who was not involved in the study. But "we're not good enough for bed bugs."
insects are parasites in bats, and researchers have long believed that the mammals were their first victims. But bat bed bugs are hard to collect - many can only be found deep in the cave where bats live. "You don't know how hard it is to find these bed bugs." Weirauch said.
these difficulties didn't stop Klaus Reinhardt, an entomologist at the Technical University of Dresden in Germany, from writing two papers on bed bugs. To study the bedbug family tree, Reinhardt and his colleagues found bedbug specimens from museums and other researchers. But the rest of the bed bugs were found by researchers in civil war-torn areas and hot, dark caves, where they trekked through knee-deep bird droppings, all with all the permits needed to study endangered bats. After the researchers collected thousands of insects, they sequenced and compared the DNA of 34 species of bedbugs to build a family tree.
researchers used a 100 million-year-old fossil and an estimated mutation rate to calculate when bed bugs first appeared and when they began to diversify. Thomas Lilley, an ecophysiologist at the Finnish Museum of Natural History in Helsinki, said the study revealed that bed bugs "existed long before bats appeared."
Reinhardt and his colleagues report in the May 16 issue of Current Biology that the oldest known bat fossils are only 64 million years old, and according to the latest research, bed bugs date back 115 million years to the time of the dinosaurs.
"It's something people've been wondering about, but it's really good to write it down in black and white." Weirauch said. Moreover, it now appears that the earliest bed bugs evolved from the ancestors of an insect that had begun to suck blood -- a method that some researchers had thought evolved after bedbugs separated from their ancestors.
family tree has also upended perceptions of bed bugs and human relationships. There are two types of insects - bed bugs and tropical semi-winged bed bugs - that usually bite. Previously, researchers suggested that the two insects originated from a common ancestor and differentiated about 1.6 million years ago, when Homo erectus had just split from an ancient human, Homo erectus. But new research suggests that the two bed bugs separated 47 million years ago, meaning they both switched independently to human blood.
, reinhardt points out, since then, one or two more bugs have turned to human hosts. For example, a study of the Hopi legend convinced him that a bedbug known to infect eagles was beginning to feed on human blood. Meanwhile, as global bird dung production increases, a "human-loving" bug, Leptocimex boueti (which also likes bat blood and is likely to be its first host), may have turned to humans. Overall, Reinhardt said, the evidence suggests that "about every half a million years, a new bug conquers humans." He added that with increasing contact between humans, livestock and wildlife, "it may not take 500,000 years" for another new bug to start sucking human blood.
, a behavioral ecologist at North Carolina State University who was not involved in the study, said the fact that bed bugs have successfully changed owners shows that they are very good at adapting to new environments.
" bedbug population has adapted rapidly to global travel, other changes in human behavior and pesticides. And Schal predicts that they will continue to do so