A research article on managing an invasive plant from the U.S. Army Engineer Research and Development Center’s (ERDC) Environmental Laboratory was recently published in a prestigious research journal.
Drs. Nathan Harms and Ian Knight’s manuscript on managing phragmites australis, an invasive wetland grass, was published in the international journal “Biological Control,” a peer-reviewed scientific journal that focuses on using living natural enemies and agents to manage and mitigate pests, plant diseases and weeds.
Phragmites australis is a perennial grass that forms dense stands in wetlands and wet areas, displaces native plants and reduces biodiversity. If uncontrolled, the plant could block drainage channels, reduce water flow, and increase flood risk. Additionally, the tall, thick grass could block visibility along roadways and railways and obstruct access to utility lines and other infrastructure. Dead Phragmites canes are highly flammable and create fire hazards for nearby structures.
Harms’ and Knight’s research focuses on using two European moth species, Lenisa geminipuncta (the twin-spotted wainscot) and Archanara neurica (the white-mantled wainscot, as biological control agents against the invasive grass. The moths bore into the grass stems, weakening them and reducing their dominance. The biological agents have been released in Canada and are surveilled to detect their migration into the United States.
Although the moths have been through decades of testing to determine if they’ll eat other plant species and were deemed safe, they will minimally eat a native species of Phragmites that grows in the United States, which is why the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) has not issued permits for the moths to be used to control the grass in the US.
Implementing eDNA found in several Phragmites stems led the two to explore this research method.
“Because initial movement into the United States would only be done on a few of the moths, finding them will be like looking for a needle in a haystack,” said Harms. “We can find Phragmites plants that appear to have been damaged by them but never find the moth in the plant. So, we developed the eDNA approach to detect the moths using tiny amounts of organic material inside the stem that came from the moth feeding,” said Harms.
Releasing the moths and allowing them to reside in the grass’ stems could offer cost-effective results, as their establishment within the grass’ stems could save land managers significant amounts of money.
“The moths are a possible long-term cost-and management-effective tool because these agents establish themselves at the site,” said Harms. “Once established, these agents could do significant damage to the plant, providing baseline control, which lowers management.”
Both biologists appreciate the recognition for their work.
“It’s super cool to see our work published,” said Knight. “We submitted this research because we believe it would be a good fit for the journal, and it’s validating that others agree that this research is valuable and that we did a good job.”
Harms added, “It feels good to know that our work will be seen by the leading experts in our field. This approach represents a significant advancement in how biological control practitioners can evaluate the establishment and presence of biological control agents. Others can also use this technique to track rare species in the environment, so its applicability extends beyond the readers of this journal.”
Harms and Knight plan to continue monitoring the northern border for the moths by keeping the eDNA approach and using moth traps with pheromones developed by Canadian researchers for further analysis.