Scientists have uncovered the fossil of a 52-million-year old beetle which lived alongside ants and preyed on their eggs.
The fossil, encased in a piece of amber from India, is the oldest-known example of this kind of social parasitism known as myrmecophily.
The research, published in the journal Current Biology, also shows the diversification of these stealth beetles, which infiltrate ant nests around the world today, correlates with the ecological rise of modern ants.
“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,” says Joseph Parker, a research associate at the American Museum of Natural History and postdoctoral researcher at Columbia University.
“This tells us something not just about the beetles, but also about the ants—their nests were big enough and resource-rich enough to be worthy of exploitation by these super-specialized insects. And when ants exploded ecologically and began to dominate, these beetles exploded with them.”
Today, there are about 370 described species belonging to Clavigeritae, a group of myrmecophilous or ant-loving beetles about 1–3 millimetres in length.
Remarkable adaptations enable these beetles to bypass the fortress-like security of ant nests which employd a pheromone code of recognition which ants use to identify and then dismember and consume intruders.
Through ways that scientists are still trying to understand, Clavigeritae beetles pass through these defenses and integrate seamlessly into colony life.
Adopting this lifestyle brings benefits.
These beetles live in a climate-controlled nest well protected against predators and they have access to a great deal of food including the ants’ eggs and liquid food regurgitated directly to their mouths by the worker ants themselves
The new beetle has been named Protoclaviger trichodens.