Andover Townsman, Andover, MA

News

Targeting a 'menace': Scientist sics her beetles on invasive plant

By Brian Messenger
Staff writer
Published: July 24, 2008

With native plant life losing a turf war in town, a freckle-sized beetle is being called upon to do what it does best — eat the invasive purple loosestrife species now choking out other plants.

At the center of this biological battle is Stevens Street resident Suzanne Robert.

Robert took on the role of beetle farmer this spring in a concerted effort to control Andover's rampant purple loosestrife population. The first battleground: the banks of Hussey's Pond in the Shawsheen area of town.

Given 40 "parent beetles," Robert raised and then released about 300 of their offspring at the pond on July 16, after the Conservation Commission signed off on the state-sanctioned biocontrol effort the previous day.

Robert is a hydrogeologist with the Massachusetts Department of Environmental Protection by occupation. She raised the PurLoo beetles — nicknamed after their preferred food source — in her driveway.

"Around the beginning of July my babies were born," said Robert. "I would go in and check on them every day."

Approved as biological control agents in 1992 by the United States Department of Agriculture, the beetles, which belong to the genus Galerucella, successfully combat purple loosestrife, Andover Conservation Director Bob Douglas said.

Though the beetles don't eradicate the plant, Douglas said their appetite for it does control the plant's ability to spread rapidly.

"Some people call that the bullet-hole pattern," said Douglas of the marks left on the plant by the beetles. "Some of the leafs on the purple loosestrife might look a little bit haggard."

Douglas said the purple loosestrife is known for its attractive purple flowers and ability to crowd out native species. It can be found throughout Andover, in wetland areas.

"It's kind of an ecological menace," said Douglas. "It's very aggressive."

First introduced to the continent from Eurasia in the early 1800s through ship ballasts and as an ornamental plant, purple loosestrife, or Lythrum salicaria, has no native predator species in United States, according to the Massachusetts Office of Coastal Zone Management, which has overseen biocontrol efforts against the plant in the state since 2000.

Nearly 30 Massachusetts communities, including North Andover, have used the PurLoo beetles to combat purple loosestrife. The plant is prevalent in multiple areas of Andover, Douglas said, not just Hussey's Pond.

"In areas with purple loosestrife we tend to see a slight decline in wildlife, so I think that's a great place to begin the test," said Douglas, referring to Hussey's Pond, located toward the end of Poor Street. "These bugs were selected to act as a bio-control. At this point, it seems they are a really good answer."

After more than a decade of "tightly controlled" experimental programs, Douglas said the consensus is that, unlike previous biocontrol failures, the beetles are not creating unexpected problems after their introduction into an environment.

"History is filled with biological disasters, of things that shouldn't be released," said Douglas. "They really are what we're looking for."

Multiple conservation directors of communities that have released the beetles in the past offered positive feedback for Douglas, he said.

"Right across the board, it had been favorable," said Douglas. "They were achieving some control and there was no downside."

Robert said the PurLoo beetles could be raised again next spring and brought to other areas affected by purple loosestrife. The beetles could also multiply on their own and travel throughout the Shawsheen River watershed, she said.

Robert said she raised the beetles in an enclosed environment with purple loosestrife plants.

"It wasn't hard at all," said Robert. "Any basic gardener who can take care of plants could take this on."

Robert said the beetles are between three to five millimeters in length and light brown in color.

"They're very tiny beetles," said Robert. "You really have to look for them."

Robert said it could take up to three years for the beetles to have a major effect on purple loosestrife population at Hussey's Pond but believes "we're going to see some results in the next year."

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