BC Recruiting Samurai Wasps for Stink Bug Battle (2018)
By Gary Symons
The BC Ministry of Agriculture is looking for a special type of warrior to help them deal with an invasion that threatens orchards and berry farms in the province.
Susanna Acheampong says Ministry officials are on the lookout for the deadly Samurai wasp, which can lay waste to populations of the invasive brown marmorated stink bug.
“We are working on a biological control, which is generally the best way to manage this pest,” says Susanna Acheampong, a Kelowna-based entomologist with the Ministry of Agriculture. “Unfortunately, we haven’t found the Samurai wasp in Canada yet, but perhaps in time we can bring them in to control the stink bugs.”
BC farmers and the Ministry of Agriculture are gearing up for the first phase of an intense battle with the invasive brown marmorated stink bug this year. Acheampong says new funding will be dedicated to putting up new traps in farms, to get an idea of just how far the stink bugs have spread into farmland.
The pesky and sometimes smelly pests are a major concern for farmers throughout the US and Canada. A 2010 study found the insect caused $37 million in damage to the US apple industry alone, and since then the stink bugs have moved into southern Ontario, Prince Edward Island and now British Columbia.
The stink bug also attacks and damages various tree fruits, berries, grapes, vegetables, corn and a variety of ornamental plants.
The first sighting of the destructive Brown Marmorated species was in Penticton in 2016, but as of November last year most of the sightings of the insect have been in or around the City of Kelowna.
“Brown marmorated stink bugs will start in backyards; that is their behaviour,” says Acheampong. “The numbers build up and then they move into our commercial crops.”
For that reason the stink bugs haven’t caused much damage to crops yet; they are still primarily being seen in urban back yards, although one stink bug was found in an orchard in Vernon.
Acheampong’s colleague Tracy Hueppelsheuser says the same thing is happening in the Fraser Valley. The BMSB varmints have been spotted in urban areas including Vancouver, Burnaby, Langley, Coquitlam, Maple Ridge, Mission, Abbotsford, and particularly in Chilliwack.
“It’s been all urban, and mainly it’s people spotting these big, weird bugs in their yards and reporting them to the Ministry,” Hueppelsheuser says.
Neither she nor Acheampong expect that reprieve to last long.
“Our orchards are very close to our downtown areas,” Acheampong points out. “We might not have a lot of time before they move into our commercial fruit.”
The Ministry is setting up additional traps in agricultural areas in the Okanagan and the Fraser Valley to track the movement and expansion of the stink bug invasion. More than 1,000 of the invasive insects were found in Kelowna’s downtown core alone between May and October of last year, when the Ministry set up more than 150 traps from Salmon Arm to Osoyoos.
Data coming in from the new traps over the spring and summer months in 2018 will give farmers and ministry officials a better idea of the size and scale of the coming threat to BC’s tree fruit and berry crops.
“For our region we don’t really know what this year is going to look like until we can complete this monitoring,” Acheampong said.
The Ministry is also asking residents and farmers to keep an eye out for the large, brown insect, to report sightings to the Ministry, and ideally to kill them on sight.
The brown marmorated stink bugs are distinguished from the native species of stink bug by distinctive white bands along their legs and their very large antennae. The regular stink bugs are not really harmful for local growers and should be left alone, but if you see one of the Brown marmorated variety, assassination is the preferred option.
The only caution is that the bugs will emit a foul stench if they are stepped on.
Acheampong says if you see one, you can vacuum or sweep it up and then kill it by immersing the bug in soapy water. Or, if you’re just good and mad and don’t mind the smell, squishing is definitely a valid option!
Stink bugs are generally dormant in a Canadian winter, revive in the spring and have two generations of stink bugs per year. They become their peskiest from September through October when the peak populations occur. The eggs can usually be found on the underside of leaves in clumps of 20 to 30 eggs per leaf, and the nymphs grow throughout the summer, becoming adults in the fall when the cycle repeats.
The bugs have a narrow, needle-like mouth, and pierce fruit to suck out the juices, a bit like a kid with a straw in a juice box. The piercing causes widespread discoloration of the fruit.
Unfortunately, the best ‘assassins’ are Samurai wasps that don’t currently exist in Canada.
“We’ve tried to find them, but they are not native to BC,” says Hueppelsheuser. “We have people looking for these wasps in insect egg masses, because that’s what they eat, but no luck so far.
“Stink bugs in general are vulnerable to egg parasites, but the brown marmorated variety doesn’t seem to be as affected by the parasitic insects we have here in BC.”
Hueppelsheuser and Acheampong say the Samurai wasps do exist in large numbers in Oregon and southern Washington State, and there is a real chance they could follow their prey into British Columbia.
“The hope is that they will find their way here naturally,” says Hueppelsheuser.
In the meantime, anyone who does spot either the BM stink bugs or one of the tiny but effective Samurai wasps is asked to contact the Ministry of Agriculture at this toll-free number: 1-888-332-3352.