Serbian weevils being used to control weeds in Banff National Park

The weevils will only feed on Yellow Toadflax

Serbian Weevils will eat the Yellow Toadflax weed in Banff National Park. THE CANADIAN PRESS

BANFF, Alta. — Hundreds of tiny beetles have been released in Banff National Park to try to fight a weed.

Known as weevils, they are being used as a biological control agent to kill the Yellow Toadflax, an invasive species that’s taken root throughout the national park.

“A weevil is a very small insect that lays its eggs within the plant and reduces the plant’s distribution by stressing it out,” said Jane Park, a fire and vegetation specialist with Parks Canada.

A total of 350 weevils — each one the size of a grain of rice — were released last week into a small test site at an undisclosed location.

Park said it’s the first time they’ve used a biological control agent in Banff National Park to prevent the weeds from overtaking native plants.

Officials went through an environmental assessment and got help from Rosemarie De Clerck-Floate, a scientist with Agriculture and Agri-Food Canada in Lethbridge, Alta., before the weevils were released in the park.

“They are little weevils that come from Serbia,” De Clerck-Floate said. “They’ve co-evolved with their host plant, which happens to be this invasive weed that came from that area of the world.

“It’s a long process getting them over here.”

De Clerck-Floate said the weevils are regulated by both the Canadian Food Inspection Agency and the United States Food and Drug Administration.

She said she first received approval to use the weevils as a bio-control agent in 2014.

“I immediately started releasing them in different climatic areas in Alberta and British Columbia, both northern and southern,” she said. “They establish pretty well everywhere, which is really good, and they overwinter.”

De Clerck-Floate said their release in Banff National Park is her highest elevation at 1,400 metres above sea level.

“I have a feeling they’ll do OK,” she said.

She said the weevils will only feed on the Yellow Toadflax, hijacking its growth, and leave native plants alone.

“It helps prevent the spread of the weed,” said De Clerck-Floate. “It takes a lot of patience. It’s not like chemical control, where you can see the effects overnight.

“Sometimes it takes many years before you see a big effect, but the fact is in many of these cases you can’t be blanket spraying herbicides.”

Park said the pilot project will be monitored in the coming years and, if it works, could become a bigger part of Parks Canada’s vegetation management program. The park already uses a combination of mowing or hand-pulling weeds, as well as a short list of approved herbicides.

“This is new to Banff, which is the use of bio-control,” she said. “It’s new to us, but it’s not new to Western Canada or North America.”

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