Chewing through a problem

Until recently, the Del Bay Retriever Club gathered at Flat Pond, a favorite area to train and exercise their dogs at Lums Pond State Park near Glasgow, Del. But, then, an invasive plant called purple loosestrife took over the natural vegetation in the pond, severely hindering the club’s activities. With mobility around the pond increasingly limited, members could not follow their dogs through the thick growth, nor could the dogs see well enough to respond to hand commands.

Purple loosestrife (Lythrum salicaria), introduced into the United States in the 1800s as an ornamental plant for gardens, now is clogging marshes and wet ditches throughout the country, according to Susan Barton, UD Cooperative Extension horticulture specialist.

“This nuisance plant, which can reach heights of 8 feet, invades nearly any wet habitat, displacing native plants and upsetting the ecological balance,” she says. “Its seeds are widely distributed, carried by wind and water, and each plant can produce 3 million seeds a summer.”

Hopeful for a solution to the loosestrife problem, retriever club member Ken Eckhardt, a retired UD sociology professor, learned about the resources in environmental research available at the College of Agriculture and Natural Resources. He enlisted the help of Judy Hough-Goldstein, a professor in the College’s Department of Entomology and Wildlife Ecology.

Hough-Goldstein viewed the Lums Pond challenge not only as an opportunity to test a beetle—an environmentally friendly insect—as a biological control against purple loosestrife, but also as a way to engage two undergraduates in real-world research. The research was funded through the Delaware Water Resources Center and the UD Science and Engineering Scholars Program.

The study combined aspects of water quality, ecological balance, entomology and plant science, with far-reaching potential. An environmentally friendly solution was needed to rid the pond of purple loosestrife without affecting surrounding native vegetation, Hough-Goldstein says. Biocontrol takes more time than using herbicides, but it is worth the wait, she says, since the beetles pose no threat to the surrounding environment or those who spend time there, including the retriever club members and their dogs.

Summer interns Jason Graham, AG ’06, an entomology major, and wildlife conservation major Jamie Pool, AG ’05, assisted Hough-Goldstein in her plan to use beetles that thrive on a menu of purple loosestrife. In June, Graham and Pool released 5,000 Galerucella calmariensis and Galerucella pusilla beetles at the Flat Pond site. These two beetles look similar and have comparable life cycles and behavior. Native to Europe and Asia, where purple loosestrife originated, the beetles usually are reared and released together. A lengthy study on their impact and host specificity was conducted before they were released in the United States.

“Beetles are bought from a beneficial-insect rearing laboratory, selling for $100 per 1,000 beetles,” Hough-Goldstein says. “Of course, the more you release, the more quickly you can get some measure of control, so we want to release as many as we can.”

Throughout the summer, the undergraduate researchers monitored the behavior of the beetles and their progress in controlling purple loosestrife. The beetles now have established a thriving colony at Flat Pond, and the level of damage to the invasive plant around the area of release has been significant. In some areas where the beetles have been released, purple loosestrife has virtually disappeared. When the beetles were finished devouring the plant’s mature stems, they entered diapause or hibernation until spring, when two new interns will pick up the study where Graham and Pool left off. Graham and Pool say they gained valuable field experience for the future, wherever their careers may lead.

“I had experience working with plants and insects doing lab work at the [U.S. Department of Agriculture] Beneficial Insects Research Center here on campus,” Graham says. “In addition to the challenge of the research, I learned something about myself. I like fieldwork. I learned what it takes to put an experiment together and monitor it for success. It’s a good feeling.”

Pool agrees. “My research experience had been confined to a microscope in the laboratory. This field study opportunity provided me invaluable knowledge,” he says. “Jason and I were given relative autonomy in developing how the study would be carried out, so we were accountable, which was both daunting and exhilarating.”

The National Fish & Wildlife Foundation (NFWF) recently announced through its Chesapeake Bay Small Watershed Grants Program a grant to the Del Bay Retriever Club to continue the beneficial insects project for controlling purple loosestrife.

“The NFWF has funded a larger-scale effort to control purple loosestrife as part of its effort to assist local groups reclaim and improve the environment for the benefit of native plants, wildlife and water enhancement,” Eckhardt says. “Some of the grant funds will probably be used to support a student to continue the research next spring and for purchase of 10,000 purple loosestrife-eating beetles.

“With Dr. Hough-Goldstein’s leadership on this project, we had a successful pilot study and are looking forward to success in 2005.”

—Susan Morse Baldwin, AS ’95M