
Samurai wasps poised to help B.C. with its stink bug problem
CBC
Brown, smelly bugs have been causing quite a stink in B.C.
The province's invasive species council recently sent out a warning about the brown marmorated stink bugs, which are chomping on a wide variety of plants and also looking to get into your house for the winter.
The number of British Columbians spotting the pests seems to be abnormally high, but experts say that doesn't necessarily mean they're worse this year.
"It's hard to say this year whether it's overall worse than in previous years," said Paul Abram, a research scientist with Agriculture and Agri-food Canada, explaining that the number of stink bugs in specific towns or regions tends to shift from year to year.
Stink bugs threaten crops, orchards and backyard gardens because they eat apples, grapes, peaches, berries, peppers, beans, tomatoes and hazelnuts.
"What we think we're seeing this fall is, because the fall is so unusually warm, the stink bugs are a lot more active — so people are seeing them more," Abram said in an interview.
Abram says he and his team on an experimental farm in Agassiz, B.C., are working to map out the DNA of the stink bugs in the province. Their research shows the local species is more closely related to brown marmorated stink bugs from China than Japan.
The bugs are present in Metro Vancouver, the Fraser Valley, on Vancouver Island and in the Kelowna area. The working theory is that they travelled with goods shipped from Asia when they started appearing in B.C. in 2015.
The good news: one of their natural predators also appears to have hitched a ride.
"We first found the wasp [in B.C.] in 2019," said Abrams, describing the parasitic samurai wasp as a "potential biological control agent" that's been used to fight off stink bugs in other countries.
Samurai wasps lay their eggs inside stink bug eggs and take about a month to emerge — killing the stink bug embryo in the process. Abrams says it's possible that when the bugs made their way overseas, the wasps came with them.
He and his colleagues have been monitoring the wasps to see if they're killing enough stink bugs to really drive down their numbers in B.C. While he says they didn't see many samurai wasps in the year after they were first discovered here, the last two years have been more promising.
"In 2021 ... we saw sometimes up to 80 per cent of the stink bug eggs were killed by the wasp," he said.
"And we found it again at several locations this year, including in the interior in Kelowna as well as the Lower Mainland."