Usually, an empty pizza box on an office desk indicates an employee just finished a hasty lunch. But in the case of Bev Dunlop, a range management specialist with Agriculture Canada in Brandon, the white pizza box on her work desk is a crucial piece of office equipment.
On a Wednesday afternoon in early July, Dunlop used a pair of tweezers to separate leafy spurge beetles from other insects and bits of grass sitting on top of the pizza box.
The beetles were from a community pasture southeast of Neepawa, Man., where Dunlop traps and collects leafy spurge beetles for an Agriculture Canada project to assess and improve the performance of the beetles in Manitoba and Saskatchewan.
The leafy spurge weed has become one of the most difficult to control pest problems on the Prairies.
“If you’ve been driving down the No. 1 Highway (in Manitoba) we need to get really interested in this because the leafy spurge has just exploded,” said Dunlop, who explained the smoothness of a pizza box offers the ideal surface for sorting insects.
“I have seen it steadily get worse and it’s moving further north…. Someone reported that they saw spurge growing along the railway line up to Churchill.”
Back in the 1990s, leafy spurge beetles were released at a number of sites in Manitoba in an effort to control the invasive species, which has choked out productive grasses on countless rangelands across the Prairies.
But after several years of monitoring the beetles and their efficacy on spurge, the program “dropped off the radar” in Manitoba, Dunlop said inside her cubicle at the Brandon Research Station.
“The biological controls were still out there. But it just seemed like everyone lost interest or funding from different agencies ran out.”
Over the last couple of years Dunlop and other Ag Canada researchers have revived the initial work on leafy spurge beetles in Manitoba. The scientists are seeking answers to a few key questions:
- What happened to the beetles?
- Where did the beetles thrive and why?
- How can we better manage the beetles in the future, so the insects can control leafy spurge?
After scouting around Dunlop and her colleagues found two sites with viable beetle populations — the Langford pasture southeast of Neepawa and another pasture near Elbow, Sask.
During a field tour at the Brandon Research Station in June, Dunlop showed how researchers place a clay pot over a spurge plant to catch the insects in a trap. The beetles crawl into a hole at the top of the pot, which leads them to a plastic container on top of the pot. Once inside the plastic container the beetles cannot escape.
The beetles are then taken to the Brandon Research Station in a plastic pill bottle, where Dunlop counts and records the number of beetles inside a trap.
Dunlop and her colleagues use the beetle counts to understand when the insect emerges and the factors that influence beetle populations, such as soil temperature, moisture and elevation at the field site.
As well, Dunlop wants to know which type of leafy spurge beetle is best suited for Manitoba’s soil and climatic conditions.
Some of beetles released on leafy spurge sites in Manitoba in the 1990s couldn’t adapt to the cold conditions in Manitoba because the insects were a beetle species originally from warmer climates in Europe. Therefore, invasive species experts need to identify beetles that can succeed in Manitoba, Dunlop said.
Rob Bourchier, a biological control expert with Agriculture Canada in Lethbridge, said soil type often determines if leafy spurge beetles flourish or fail.
Black leafy spurge beetles do well in Alberta but brown beetles are better suited for the eastern Prairies.
“The brown beetles tend to prefer sandier soils, which is more appropriate for Manitoba and Saskatchewan, where the spurge is (located),” Bourchier said.
Compared to Manitoba, where leafy spurge beetles never totally gained traction, they have become a critical weapon in the fight against leafy spurge in southern Alberta.
Since 2001, Bourchier has led a coordinated campaign to control spurge with beetles. In total, the insects have been released at more than 600 sites south of Calgary and east to the Saskatchewan border.
By 2009, a number of nurse sites for beetles were established in southern Alberta, so Alberta Agriculture reps could access local supplies of beetles.
“What we were trying to do is get a site from which the fieldmen, or their staff, could collect (beetles) and re-distribute within their region,” Bourchier said from his office in Lethbridge.
The beetle program hasn’t eradicated leafy spurge but there are places were the invasive weed is now under control.
For instance, beetles have restrained the leafy spurge at the Waldron Ranch near Pincher Creek, Bourchier said.
“We have had local successes. We haven’t eliminated spurge in southern Alberta and we never will because you’re always going to get this seeding and spread (of leafy spurge seed),” he said.
“(But) if we stopped tomorrow the spurge would just take off again…. We have to be continually moving the beetles and getting them to the spots where they need to be.”
Bourchier would like to see a similar program in Manitoba, where landowners and agencies can acquire beetles from specific sites and distribute the critters to fields with a spurge problem.
Having a population of local beetles, adapted to the environmental conditions and soils in Manitoba, would be fantastic, Dunlop said.
Nonetheless, even if Manitoba does adopt an Alberta-type beetle program, it won’t be a leafy spurge panacea, she added.
“You need an integrated pest management approach. You just can’t use beetles and you can’t just use mowing, or cattle. You need it all.”