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‘Freaky’ vines slowly wrap around wasps and turn them into mummies, scientists say

Parasitic plant attacks parasitic insect on South Florida oak tree

Rice University evolutionary biologists have discovered a new trophic interaction -- the first example of a parasitic plant attacking a parasitic insect on a shared host plant. Cassytha filiformis, or love vine, is common on four continents.
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Rice University evolutionary biologists have discovered a new trophic interaction -- the first example of a parasitic plant attacking a parasitic insect on a shared host plant. Cassytha filiformis, or love vine, is common on four continents.

It may be called the “love vine,” but this creeping vine has a sinister secret — and no love for the wasps that buzz around its habitat in the trees.

The vine, whose official name is Cassytha filiformis, can’t survive on its own, so it attached itself to trees, snakes its tendrils into their tissues and absorbs their nutrients, Popular Science reported.

But that’s only the beginning.

Now scientists from Rice University say the parasitic plant appears to find, ensnare and slowly mummify certain species of wasps by sucking out their nutrients before they’re able to escape — leaving them dried out as mummified husks.

“I had never seen this,” evolutionary biologist Scott Egan said in a news release.. “But the fact that no one, as far as we know, had ever documented this was incredible because biologists have studied each of these — the vines and the insects — for more than a century.”

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Cassytha filiformis, commonly known as love vine, is a parasitic plant that’s common on four continents. S. Egan/Rice University

The wasps in question are gall wasps, so named because they land on trees and form small, hard balls of “gall” out of the bark. These balls act as tiny fortress cocoons for their young, providing the developing wasps with nutrients and shelter as they develop.

“The larva secrete an enzyme that cause the tree to grow a tumor around it. The gall is actually part of the tree. It is as if you had cancer,” Guy Sternber, author of Native Trees for American Landscapes, told the Southern Illinoisan.

“The wasps induce them to grow at the site where they lay their eggs, but the galls are part of the tree. The cells there have the same DNA as any other cell in the tree. They’ve just been reprogrammed to grow and behave in a way that is ultimately harmful to the tree,” Egan wrote in a news release.

This is the first time scientists have seen a different parasite — and a plant one at that — preying on the wasps inside the gall. “Basically, you have a parasitic plant attacking a parasitic insect inside of another host, a host they share,” Egan said in the release.

In the study, published in the journal Current Biology, the scientists explain how the vines seem to attach themselves to the gall and suck out nutrients from inside. When they dissected those gall balls, they found 23 “‘mummified’ wasps inside.

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Rice University bioscientists found that love vines attach themselves to galls, extracting energy from the nurseries at the expense of the young wasps inside. Biologists found dead, mummified wasps in almost half of the attacked galls they opened. Mattheau Comerford/Rice University

“If we can find out how the vines identify the galls, how they zero in on them, it could potentially provide new clues for targeting and fighting cancer,” Egan said in the news release.

Graham Stone, a biologist at the University of Edinburgh, called the discovery “really good fun” but also “pretty freaky,” according to The Atlantic.

“I think this is a fascinating new interaction … a new facet of all the possible interactions galls can have,” Karsten Schönrogge, an ecologist, also told the magazine.

In the study, the scientists said the discovery could have “global” implications, with thousands of parasitic plants possibly preying on some of the 13,000 insects known to form gall around the world.

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