worms plant ragweed seeds

http://www.sciencenews.org/view/generic/id/33699/title/Ecosystem_engineers

Led by weed ecologist Emilie Regnier of Ohio State University in Columbus, researchers conducted field experiments to determine how exotic European night crawlers, Lumbricus terrestris, affected the survival of the seeds of Ambrosia trifida, giant ragweed.

In addition to its powers as an allergen, ragweed is a major weed of soybean fields and cornfields in the Midwest, Regnier says. This fact has puzzled scientists because ragweed seeds are usually quickly eaten by birds, rodents and beetles.

Worms collected and buried more than 90 percent of ragweed seeds from the surface of the soil around their burrows, the team reports.

“The burrow is an environment that the worm is actively maintaining — that’s its universe,” comments soil and ecosystem ecologist Patrick Bohlen, director of the MacArthur Agro-ecology Research Center in Lake Placid, Fla. “Maybe it’s sweeping its front porch. We don’t really know. There isn’t a lot of evidence that they are eating the seeds, but clearly it’s creating an architecture.”

Do they plant other seeds too? We want to know.

Maybe worms like ragweed seeds as gizzard stones.

I was hoping this could be a deep-dyed plot between Lumbrici to spread the seeds, and trifid Ambrosia to... strangle competitor worms with its roots, or something. But ragweed is exotic to Europe.

ETA: sock puppets! mouth suction!