Release the bugs: biocontrol in action

Flea beetles are released on leafy spurge before they lay eggs. The larvae attack the weeds’ roots.  |  William DeKay photo

The beetles sounded like popcorn popping as they jumped around in their holding bags.

The more than 20,000 leafy spurge flea beetles were part of a recent effort to use biocontrol options rather than herbicides to stop the spread of a devastating weed.

The Meewasin Valley Authority, which manages the South Saskatchewan River Valley in and near Saskatoon, released the insects into two of its seven monitored leafy spurge sites late last month.

The Fred Heal Conservation Area and Chief Whitecap Park are covered in more than six acres of the invasive bright yellow weed.

Both sites are on a flood plain, which makes biocontrol the most viable solution.

Renny Grilz, a resource management officer with Meewasin, said integrated management practices are the solution, but some areas require more diligence.

“We’re a little more leery on spraying. We will be doing some spraying there, but it will be more small patches,” he said.

Grilz and his team collected their beetles at a collection site in the Besant Campground near Moose Jaw, Sask.

The provincial agriculture ministry arranged the collection, and Grilz said there’s only a small window in which to catch the beetles.

“It’s a week long collection (from) the last week of June to the first week of July,” said Grilz.

Eryn Tomlinson, a resource management technician with the authority, said the beetles start reproducing by mid-July, so it’s important to collect them before then.

“It’s actually the larvae that do the most damage, so we want to get to the beetles before they lay eggs,” she said.

“We want them on our sites (to) lay eggs so the larvae will actually mine out the roots of the plant. That’s really what does the most damage.”

Hot sunny days are great for collecting as the beetles rise to the top of the plant and are more visible, said Tomlinson.

“We would just sweep back and forth and then once we had a significant amount in our nets, we just sort of tipped them upside down into the paper bag and then duct taped the bag up,” she said.

The net sweeping is labour intensive, but transport and release are simple once the insects are caught.

The team places the beetles on ice in a cooler to put them into a dormant stage and keep them cool so they don’t die during the trip.

Grilz chooses and documents the best release sites once the beetles arrive on site.

“We do a lot of partnership work with the ministry of agriculture and the Saskatchewan Conservation Data Centre,” he said.

“We’re mapping all our invasive species, and we’re mapping our management activities.”

Grilz, who sits on the Invasive Species Council’s board of directors, said they are trying to create more public awareness of biodiversity and invasive species control.

The program Play Clean Go creates awareness about the transference of weeds in the United States, and Grilz hopes the council will partner with it next year.

“We’re hoping to get funding to use that program and signage to create awareness that talks about hikers, quadders (and) dog walkers,” he said.

Ruth Gosselin owns a pasture in the South Saskatchewan River Valley on which leafy spurge beetles have been used for a few years.

“Where there was spurge and we placed the (beetles), its gone back to grazeable land,” she said.

A Brandon University study found that a 40 percent infestation of leafy spurge decreases the carrying capacity of cattle by 50 percent.

“We’re going to keep doing it,” Gosselin said.

“I don’t think we have another option unless we want to spray, and we don’t want to spray.”

The beetles are not a quick fix and it takes years before they’re effective, but it’s less expensive than spraying and healthier, said Gosselin.

“I think going with the beetles is the long-term solution.”

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