Researchers found an ant-loving beetle in a piece of 52-million-year old amber.
These ancient beetles were most likely able to live alongside ants undetected while feeding on their eggs. The specimen is the earliest-known example of this type of social parasitism known as "myrmecophily," the American Museum of Natural History reported. Similar beetles still infiltrate ant nests today.
"Although ants are an integral part of most terrestrial ecosystems today, at the time that this beetle was walking the Earth, ants were just beginning to take off, and these beetles were right there inside the ant colonies, deceiving them and exploiting them," said lead author Joseph Parker, a research associate at the American Museum of Natural History and postdoctoral researcher at Columbia University, who is a specialist on these beetles.
The findings suggest ancient ants built nests large enough to be exploited by the beetles, and once the ant population exploded they facilitated an increase in the beetle population as well.
Today there are about 370 described species of ant-loving beetles between one and three millimeters in length. Researchers are still trying to figure out how this family, dubbed Clavigeritae beetles, pass through the ants' line of defense and invade their colonies.
"Adopting this lifestyle brings lots of benefits. These beetles live in a climate- controlled nest that is well protected against predators, and they have access to a great deal of food, including the ants' eggs and brood, and, most remarkably, liquid food regurgitated directly to their mouths by the worker ants themselves," Parker said. "But pulling off this way of life means undergoing drastic morphological changes."
These beetles boast fusions of segments within the abdomen and antennae providing additional protection of ants, which often pick them up and carry them around the nest. They also have recessed mouth pieces that allow them to accept liquid food from worker ants. Glands cover the beetles' bodies with oily secretions and thick brushed of hair conduct chemical-containing secretions from nearby glands, which could be the secret behind why the ants "adopt" these beetles.
"If you watch one of these beetles interact inside an ant colony, you'll see the ants running up to it and licking those brush-like structures," Parker said.
The ancient specimen's body is very similar to that of modern Clavigeritae beetles, but also have some more primitive characteristics. Protoclaviger's (the 52-million-year old beetle) abdominal segments are still distinct, while modern insects possess more "armor."
The findings were published Oct. 2 in the journal Current Biology.
