Can imported beetles from B.C. save N.B. forests?

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New research into battling invasive insects threatening New Brunswick trees suggests using other imported bugs to wipe them out.

The research, by Jeff Fidgen, a forest health biologist at the Atlantic Forestry Centre, and Chris MacQuarrie, a research scientist at the Great Lakes Forestry Centre in Ontario, was shared at the Atlantic Canada Forest Health Workshop in Fredericton last week.

It suggests introducing a tooth-necked fungus beetle from British Columbia to control hemlock woolly adelgid populations and using similar biocontrol tactics against the emerald ash borer.

Fidgen said insects are typically flown into areas where pests aren’t native species and don’t have the natural predators required to keep their populations low.

“Depending on what the science shows is effective, the idea is to suppress the pest population so that the trees can survive in the presence of these invasive species,” he said.

Hemlock woolly adelgid aren’t known to be in New Brunswick, but Fidgen said the species is in Nova Scotia and has done a number on the province’s hemlock trees, which form some of the last remaining old-growth forests. The tooth-necked fungus beetle used to control their populations is native to western North America and has been used since 2003 across the northeast to manage infestations.

Fidgen said many precautions are taken before the beetle is released in a new environment, including tests to see if the insect will eat any other species. He said tests were also conducted in Nova Scotia to see if any existing insects were preying on the pest. Once that research is done, a federal authority reviews the information and approves the insect release.

“We’re not bringing an insect in from another country,” he said. “Another part of my work involves detecting the adelgid using traps we put out across Nova Scotia and southern New Brunswick to detect the DNA of the adelgid so we know if they’re present in the area.

“If they’re present, and depending on the resources at risk, we would consider doing any number of treatments for what we find. We need to manage population levels so we don’t get a lot of tree mortality.”

If the insect is only found in a few trees, Fidgen said, forestry officials would likely cut the affected trees and burn them. But if they’re more widespread, controlling the population by bringing in predators would get more consideration.

Biocontrol tactics to control invasive species in Atlantic Canada aren’t new. Fidgen and MacQuarrie said parasitic wasps have also been released in recent years to target the emerald ash borer, a beetle that’s native to northeastern Asia and feeds on ash trees. The species has been in New Brunswick since 2018.

MacQuarrie said biocontrol programs have been used against the emerald ash borer since 2013, with three wasp species that feed on the beetle being released in Fredericton, Moncton, Halifax, and Ontario. He said the goal is to protect up-and-coming trees, as older ones hit by the emerald ash borer are likely beyond saving.

“These insects lay their eggs inside the grub under the bark of the tree, or inside the emerald ash borer’s eggs, then eat the emerald ash borer and come out and attack more,” he said. “The idea is to kill the insects before they can damage the tree.”