Now here’s a headache of historic proportions: An ancient ant with a mite attached to its head has been found preserved in amber, a new study says.
The unlucky ant and its likely parasitic hitchhiker were trapped in tree resin, which eventually fossilized into amber, about 45 million years ago. The discovery is the oldest evidence of a mite attacking a social insect, according to the study, published September 9 in the journal Biology Letters.A picture of the fossil shows the mite attached to the ant’s head. Photograph by Jason Dunlop
The parasite is called a mesostigmatid mite, a kind of small, eyeless arachnid found in soil and leaf litter. Study leader Jason Dunlop said you’re most likely to encounter one of these mites when gardening: “They are tiny, fast-moving, often orange-colored mites that run around skittishly in the earth.” (Also see “Speedy Mite Is World’s Fastest Land Animal (Relative to Size).”)
Though mites are common—there are more than 11,400 species alive today—finding fossilized mites is unusual, probably because the soil-living creatures are quickly consumed by scavengers after they die.
“In this case, we had a piece of good fortune in that the mite was being carried by a larger and more mobile animal—an ant—which somehow got itself caught in the sticky tree resin and brought the mite with it,” said Dunlop, an arachnid expert at the Leibniz Institute for Evolution and Biodiversity Science in Berlin.
Paul Selden, an expert on fossil arachnids at the University of Kansas who was not involved in the study, added: “There a lot of interspecies interactions found in amber, including parasitism, but this find is nice because mesostigmatid mites are rather rare in the fossil record.”
The researchers discovered the fossil in the natural history collection of Joerg Wunderlich, a German paleontologist. It’s not known exactly where or when the fossil was found, but similar amber fossils have come from the Baltic coast of Russia. (Also see “Triassic Mites Join World’s Oldest Amber Animal Finds [Pictures].”)
Dunlop and his colleagues studied the specimen under a microscope and created images of what they saw. The results reveal the mite belongs to a family whose living species are thought to parasitize ants, and the ant is of the species Ctenobethylus goepperti.
Mites are often found living with ants, though scientists don’t know exactly what the mites do to the ants. But the discovery offers a new clue by showing that the phenomenon has occurred for at least 45 million years—much longer than thought.
“The technical term for an animal that lives among ants is myrmecophilous, which is Latin for ‘ant-loving,'” Dunlop said.
“For the ant, however, these mites are presumably a nuisance, and perhaps even dangerous. This ancient ant was almost certainly not enjoying carrying the mite around with it.” (See “‘Vampire’ Parasite Found Entombed in Amber.”)
The mites attach themselves to the back of an ant’s head using sucker-like pads on the ends of their stubby legs. It’s unknown what the mites would get out of this association.
Fossil Could Help Honeybees?
Figuring out when mites evolved to parasitize social insects could help modern scientists, too.
For instance, Varroa mites, which are related to the mite found in amber, are a major pest of honeybees and cause considerable economic damage—and may play a role in colony collapse disorder. (Related: “The Plight of the Honeybee.”)
This fossil shows not just two creatures trapped in amber together, but also some clues about what their relationship in life was like, added David Penney, a paleontologist from the U.K.’s University of Manchester who wasn’t involved in the new study.
“Understanding when and how different behaviors evolved is part of the process paleontologists go through when studying fossils,” he said.
“Unique and remarkable fossils like this one are extremely important in piecing together the jigsaw puzzle.”