Washington State University entomologist Jennifer Andreas plans to soon petition the USDA to allow a non-native insect be turned loose on an invasive weed that she calls, respectfully, “a beast.”
Flowering rush, an aquatic plant native to Eurasia, has escaped in the West, presenting a choking hazard to irrigation systems. Hard to pull and tough to poison, the weed has no natural North American predator to check its growth.
For almost 10 years, Andreas and other researchers have been studying how to beat back flowering rush with “classical biocontrol,” the science of importing a foreign bug to fight a foreign weed.
It’s not done lightly. Scientists spend years studying whether introduced insects will do harm by straying off target and killing beneficial native plants. The payoff is weed control without annual herbicide applications.
“There is no zero-risk option. If you spray there’s a risk in that. If you do nothing, there is a risk,” Andreas said. “Biocontrol is quite low risk.”
Andreas said she hopes this spring to submit a petition to release Bogous nodulosus, a.k.a. “flowering rush weevil.” A technical panel will review the petition and advise the USDA Animal and Plant Health Inspection Service. A decision is likely to be years away.
With APHIS approval, the weevils could be let go, probably first at Flathead Lake in Montana, the source of flowering rush root fragments floating west into Idaho and Washington.
In Eurasia, the weevil eats flowering rush rhizomes, or rootstalks, “hitting it where it hurts,” Andreas said. She said she’s excited to see how the weevil will work in North America.
“Flowering rush is sort of a beast of a plant, and we’re kind of losing the battle to get rid of it,” she said.
Andreas, based at WSU’s research center in Puyallup, directs the WSU Integrated Weed Control Project, a program primarily funded by the U.S. Forest Service.
She also leads the international Flowering Rush Biocontrol Consortium and co-chairs the biocontrol committee of the North American Invasive Species Management Association.
For a question-and-answer session on the association’s website recently, she named flowering rush her “favorite invasive species.”
“You have to respect a weed that is besting us at almost every turn,” she said.
Andreas said the remark was somewhat tongue-in-cheek, but also true.
“I would say I have a certain respect for some of these invasive species that are challenging for us,” she said.
A native of Canada, Andreas went to the University of Lethbridge in Alberta and with the help of a “great professor” was introduced to the wonders of entomology. “I think insects are incredible,” she said.
After graduating from Lethbridge in 2000, she enrolled at the University of Idaho and earned a master’s degree in entomology in 2004.
She went to work for WSU Extension in King County in 2005 and later moved to Puyallup.
The WSU program Andreas directs promotes controlling weeds by all means, including biocontrol.
Most biocontrol experiments fail, according to APHIS. Sometimes transplanted insects don’t reproduce in their new environment or aren’t that effective.
According to the Centre for Agriculture and Bioscience International, the last biocontrol agents to have notable success in the western U.S. were a wasp and a midge introduced in 2008 and 2009 to control Russian knapweed.
Recently, however, APHIS has authorized some promising releases.
“We did have a kind of quiet, nothing-happening phase, but we’re taking off again,” Andreas said. “I think we’re getting excited again.”
APHIS in 2019 permitted the release of a weevil, Ceratapion basicorne, to attack yellow starthistle, a weed that damages grazing lands in Washington, Oregon, Idaho and California.
The prickly plant is Andreas’ least favorite invasive species. “I hate working in it. It’s so painful,” she said.
In 2020, APHIS permitted the release of a psyllid, Aphalara itadori, to control Japanese knotweed, as well as the related Bohemian knotweed and giant knotweed.
The insect was released last spring in Grays Harbor, King and Pierce counties. Andreas will be checking in early spring this year to see how the insect fared over the winter.