New Brunswick

Tiny wasps released in Edmundston to fight emerald ash borer

New Brunswick has a new secret weapon to fight against the emerald ash borer.

Between 500 and 1,000 mite wasps will be released this summer to combat the emerald ash borer

The invasive beetle, which has few enemies to keep it in check, was found in Edmundston last May and could be on its way to Fredericton. (Minnesota Department of Natural Resources/The Associated Press)

New Brunswick has a new secret weapon to fight against the emerald ash borer.

A shipment of mite wasps arrived last week at a woodlot near Edmundston — the tiny wasp is one of the only known weapons against the destructive emerald ash borer, an invasive beetle that has destroyed millions of ash trees in parts of North America.

Chris MacQuarrie, a research scientist with the Canadian Forest Service who is working on the project, said between 500 and 1,000 mite wasps will be released in the area this summer.

"We'll do this twice now and twice later in the summer," he said.

The wasps are one millimetre in size and harmless to humans, but they have an affinity for the emerald ash borer.

The wasps work in stages, first attacking and feeding on the eggs of the emerald ash borer and then the larvae.

The wasps are grown in Michigan and MacQuarrie's forestry centre in Ontario. But it will take about four years to see whether the wasps establish a local population.

Science inconclusive 

Although the science is still inconclusive, MacQuarrie said he thinks the insects could help control the ash borer's spread.

"We haven't been doing this for tremendously long and we haven't had the chance to see what the long-term interaction is between the emerald ash borer and these parasitoid wasps we released."  

The biggest threat to the forest is people actually moving these pests around.-Chris MacQuarrie, research scientist

The mite wasp has been used to fight the emerald ash borer in places like Michigan in the mid-2000s.

"They found there's be a reduction in the size of the emerald ash borer population and they've seen those sites of ash trees have started to come back," he said. "They've associated the two things together."

The mite wasps were later released in Ontario and Quebec about 10 years later and now New Brunswick is using the tiny insect to combat the emerald ash borer.

Before any of these insects were allowed in North America, he said researchers had to test and make sure the wasps didn't eat other North American species "closely related to the emerald ash borer."

Borers can live beneath the bark of ash trees for more than two years before obvious signs of infection start to show. (Holly Caruk/CBC)

"All that science has to be reviewed by a whole bunch of other scientists and everybody has to agree that it's safe before we can do any of these kind of releases," he said.

Both species are native to Asia. But the emerald ash borer was first detected in 2002, according to Natural Resources Canada. It was detected in Edmundston just last year.

Fredericton ash trees at risk

Fredericton has about 10,000 ash trees in Odell Park alone and about 2,400 along city streets. The numbers don't include ash trees in other city-owned parks or on private property.

Ash trees have limited resistance to stave off the insects, which can kill trees within one to four years of infestation.

Meanwhile, Jessica Wiley, manager of forestry for the City of Mississauga, spoke to city officials in Fredericton last week, where she suggested inoculating the local trees with pesticide.

On their own, the emerald ash borer only travels about 400 to 700 metres a year, but with people moving firewood from province to province, the ash borer can travel much farther.

"The biggest threat to the forest is people actually moving these pests around," MacQuarrie said.

With files from Information Morning Fredericton