A tiny creature is proving to be a big foe for a non-native plant. Leaf beetle species called "Cella" beetles feed on the shoots and leaves of the aquatic invasive purple loosestrife.
The DNR, UW-Extension and citizen volunteers have been introducing these natural enemies of purple loosestrife in Wisconsin since 1994.
John Bie, Woodruff, has been volunteering time toward the bio-control effort since 1998.
"It's nature against nature," Bie said. "They actually brought the beetle in ... from its native area." The beetles, like the purple loosestrife, hail from Europe.
Studies were done for a number of years at the University of Minnesota, Bie said. Research included putting various different kinds of plants with the purple loosestrife beetles to see what else they might eat.
"They wanted to make sure they weren't going to have a pandemic of beetles that eat everything in sight," Bie said. But the beetles are fussy eaters.
"They're a very, very selective animal. They will feed on just the loosestrife," Bie said.
Bie started out working with Cathy Cleland, who was a water resources specialist with the DNR. Back then, Bie had a little funding from the state.
"It'd buy the potting soil for the plants, and maybe a little fertilizer, and that was about it," Bie recalled. "Almost everything else I did on my own."
In the absence of that help, Bie has continued anyway.
"I just believe in the program that much," he said. "It's not running me hundreds or thousands of dollars, or anything like that. I get four or five bags of soil for a couple bucks a piece ... 10-15 bucks for a little bag of fertilizer, and I'm off and running. But there's time involved."
One thing Bie got from the state was netting. The netting gets pulled over the host plants, forming a tent and keeping the beetles in and the predators out.
"They had somebody who was making them, so I got a bunch of those," Bie said. "And I guard them jealously - I really take care of them. I've had them all these years and they've held up."
Bie said he and others were ranging as far south as Marathon County and as far north as Trout River with Cleland.
"A lot of times it involved dragging boats through a lot of muck and pushing upstream, and wading up streams to get to the loosestrife," he said. "They are a wetland plant. They grow on shorelines, but the wet, wet shorelines."
Bie described the Minocqua thoroughfare as his "nursery."
"I go down there in the spring, after I've picked up my plants and gotten them going. Once the plants are in the netting and growing ... I go get the beetles."
It's a fairly laborious process. The temporary holding container is usually a pop bottle with its top cut off and inverted, forming a funnel-like entrance. The two pieces are taped securely. Beetles are tapped into the makeshift container. Bie said he puts a few leaves in the bottom of his. A wad of cotton secures the opening.
Care is taken. The beetles are wary.
"If they sense danger, they'll drop, and then you can't find them," Bie said.
Once enough beetles are captured, they are distributed to their host plants. Bie said "it can be hell-on-wheels, when you take that tape off and you've got 200 beetles coming up."
He cools the beetles down before releasing them from their container, which slows them down and makes them easier to transfer. Bie dumps the beetles out in a cooler and divides them.
He uses a specialized tool. It's a small jar with a rubber stopper. The stopper has two short plastic tubes passing through it, with a length of flexible rubber tubing affixed to one. The "operator" holds the flexible hose over a beetle, and sucks in through the other tube, pulling the beetle into the jar. A piece of mesh assures that a beetle won't come up through the mouthpiece.
After about 10 beetles are gathered in the jar, they're transferred to a tent, which is closed securely at its top. Several hundred offspring are likely in each tent.
"When those larvae come out, those little guys just destroy the plant," Bie said. Sometimes he adds other plants he has grown separately.
The plants are raised in plastic wading pools, and the water isn't allowed to get too high, because somewhat dryer soil is needed near the surface to help the beetles proliferate. After a certain point, they're moved to the site of a purple loosestrife infestation.
"My own area of concentration has been the Minocqua Chain," Bie said.
Purple loosestrife can be controlled, but it can't be eradicated, Bie noted.
"People need to understand that this will never be gone," he said. "Loosestrife will never disappear unless we do something with genetics on plants ... We'll always have loosestrife, but we won't have it to the point where it destroys our wetlands."
He pointed out the Minocqua thoroughfare, which he says has been subject to the bio-control for a number of years.
"You still have your cattails, your sedges, your arrowroots are still there. If we had not done anything, they would not be there. It would be all loosestrife."
Loosestrife root systems can go down two or three feet, Bie said.
"You can't just go in there and say, 'I'll just pull'em out.' You'll pull'em out ... but the roots are there, and they'll come right back."
Bie said anyone pulling loosestrife plants by hand should shake them to loosen the beetles.
"They can fly, and they'll travel to search for food," he said.
Bie lauded recent efforts by inmates at the McNaughton correctional facility in rearing the beetles.
"The guys down there are real enthusiastic about it, so I'm pretty happy," he said.
Craig Turk may be reached at firstname.lastname@example.org.
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