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Entomology students enlist beetles in battle against invasive weeds
4:58 p.m., Aug. 21, 2006--During the summer, most students leave UD to pursue jobs or other activities. But for some undergraduates, their work is right here on campus. Kelsey Paras, AG '08, and Jason Graham, AG '07, spend their summers doing research in the laboratories and greenhouses of Townsend Hall and in nearby fields. Under the supervision of Judith Hough-Goldstein, a professor of entomology and wildlife ecology, Paras and Graham are waging a battle against invasive weeds, investigating ways the weeds can be naturally controlled and conducting other research that will continue beyond the summer. Paras is working with weevils, small black insects that feed on mile-a-minute weed, an invasive alien vine from Asia. The vines, which can cover nearby plants, can grow to more than 6 meters and threaten habitats in the Mid-Atlantic region. Hough-Goldstein said they have been looking for a biological control agent, or insect, that would feed on the weed and control its spread when they discovered weevils. In the summer of 2004, weevils were released in small amounts in Delaware and New Jersey. In 2005, more weevils were released in New Jersey, West Virginia and Pennsylvania. Paras researches ways to ensure the weevil population can control the growth of the weed without upsetting the environment's balance. “I'm working to make sure the weevils won't become a pest species,” Paras said. Paras studies the weevils to determine if they have any natural predators in the area, which would help keep the weevil population in control. Paras said she feeds weevils to wheel bugs, whose piercing mouthparts are able to break apart weevils. She also places Petri dishes outside with weevils and fruit flies as a control to see if they are eaten. Paras helps out graduate students in the field, as well. Paras said weevils are an excellent way to control the spread of mile-a-minute weed. “We are trying to control an invasive species,” she said. “Biological controls are a good choice for that because they won't have a negative effect on the environment, unless it gets out of control.” Paras also noted that when weevils first emerge from their eggs, they are black, but later turn orange. Paras said she is trying to determine if predators eat the orange weevils, as well as the black ones. So far, Paras has noted that predators enjoy both colors of weevils. Paras conducts her research using weevils from a large screen cage in the laboratory, which contains mile-a-minute weed. She also has rearing tubs by the greenhouse so she always has a supply of weevils. Paras said the growth cycle for a weevil is approximately 26 days. Paras also volunteers for four days a week at the Tri-State Bird Rescue and Research organization in Newark. She feeds baby birds and gives them medicine. She also offers weevils to robins to see if they will eat them. Paras said she usually spends her summers lifeguarding, but is enjoying her experience in research. “This is very different from what I am usually doing,” Paras said. “I like it a lot. I think the project is really interesting.” Graham has been recording the fight against another form of invasive weed since the summer of 2004. He is researching the release of Galerucella beetles, a European species, to control the spread of purple loosestrife. Graham is in charge of monitoring the beetles at Burrow's Run in Hockessin and Flat Pond in Bear. To do this, Graham said he looks for beetles on the weed and fills out data sheets that record population, the presence of other plants and insects and any damage to the weed. “It can take half a day to get to each site and complete a monitoring session,” Graham said. “While I'm in the field I also usually spend some time collecting insects for our laboratory experiments. Other days I spend typing up the data, caring for plants and insects in the greenhouse, caring for insects in the laboratory, reviewing literature related to my research, meeting with Dr. Hough-Goldstein, planning the research and conducting experiments.” Graham said he believes it will take a while for the beetles to build a large enough population to control the purple loosestrife, but is hopeful that they will reach that stage. Graham said there have been a few surprises in his research. In 2004, they released 3,000 beetles at Burrow's Run and did not see them again until last summer, when they stumbled upon a small population of beetles while conducting a different experiment. Graham said guidance and encouragement from Hough-Goldstein helped to direct his research. “She was always available to field ideas and help plan experiments,” he said. “Having a such a good mentor made the experience much more rewarding.” Like Paras, Graham said he enjoys his research project. “The project itself was interesting to me because I had the opportunity to be out in the field watching this research take place,” he said. “Week in and out, I witnessed the dynamics between the beetles, the purple loosestrife and the other plants and insects which made up their surroundings. This project has not only provided me with a job for the past three summers and a basis for my senior thesis but has given me the skills I'll need to carry out future research and the experience to know I'll enjoy it.” Hough-Goldstein said the summer interns are doing very well in their projects. “I've been really impressed with them,” she said. Article by Julia Parmley, AS 07 |
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