Evidence of 'zombie' Parasite in Fossil

EXETER, England, Aug. 18 (UPI) — Parasites that control their hosts and turn them into “zombies” may have learned their macabre trick almost 50 million years ago, U.K. researchers say.

Scientists at the University of Exeter say a fossilized leaf has revealed the oldest known evidence of the phenomenon, and gives clues to where and when such parasites evolved, a university release said Wednesday.

“This leaf shows clear signs of one well-documented form of zombie-parasite, a fungus which infects ants and then manipulates their behavior,” Dr. David Hughes of Exeter’s School of Biosciences said.

The fungus, called Ophiocordyceps unilateralis, makes ants leave their colonies and head for a leaf that provides the ideal conditions for the parasite to reproduce.

When the “zombie” ant gets there, it bites down hard on the major vein of the leaf in a “death grip,” so when the ant dies its body remains, giving the fungus time to grow and release spores to infect other ants.

The death grip bite leaves a very distinct scar on the leaves, the researchers say, and they found clear evidence of it on a 48-million-year-old fossilized leaf specimen from Germany.

“The evidence we found mirrors very closely the type of leaf scars that we find today, showing that the parasite has been working in the same way for a very long time,” Hughes said.

“This is, as far as we know, the oldest evidence of parasites manipulating the behavior of their hosts and it shows this parasitic association with ants is relatively ancient and not a recent development.”

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