Earthworms and Herbicides: Nicole Lidzbarski ’18
Nisbet Honors student Nicole Lidzbarski ’18 was part of an award-winning student-faculty team researching the potentially carcinogenic effects of common herbicides in their project, “Investigating the Toxicity and Accumulation of a Medically Important Herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D) Using Earthworms as a Model System.” Their goal was to examine how two chemicals which are the active ingredients in the herbicides Roundup© and Trimec© affect the health of earthworms. A new, popular herbicide called Enlist Duo© combines these two chemicals.
“As both chemicals will be applied directly to leaves,” the team wrote in their abstract, “the safety of other organisms that come into direct contact with vegetation or contaminated soil needs to be investigated.”
“Earthworms are an important part of the soil ecosystem,” the team wrote. “Not only are they in direct contact with the soil, but they also ingest the soil containing organic matter along with any contaminants. As earthworms constitute a food source for other organisms, bioaccumulation is possible.”
“The most surprising thing was actually the process of research itself,” Nicole said. Nicole is a math major who was convinced by her friends to join the summer research project after enjoying a science class together. “I knew that research is not as straightforward as you might think, but I didn’t realize the extent of the complexity.”
The students had four chemical variables to test: each chemical alone, the two chemicals combined, and a control group with no chemicals. They also had several methods of exposure: applying the chemicals directly to the earthworms, putting it into the soil housing the earthworms, and applying it to the leaves of plants sharing soil with the earthworms. They tested varying concentrations of the chemicals as well as different ratios of the chemical combination. They looked at earthworm mortality rates, but also developed methods to detect bioaccumulation of the chemicals in the earthworms’ tissues.
Research vs. Science Lab
Nicole noted a powerful contrast between original research and the controlled “experiments” of a typical classroom science lab.
“My advisor says ‘It wouldn’t be research any more if you always knew what was going to happen.’ In lab, you have a procedure to follow, and you’re just analyzing results. But when you’re doing actual research, it’s up to you to figure a lot of that out yourself. It’s a lot of trial and error: What can we do? How can we fix it? It’s a lot of analysis of what went wrong.”
An example of trial and error learning? “We originally watered all the plants the same but then we realized that the solution in which we put the herbicide was diluted with water. This was effectively watering the herbicide group more than the control group, so we had to adjust.”
Why Does It Matter?
Nicole feels their research is significant because previous studies have suggested that both of these ingredients are potentially carcinogenic. Her team discovered that earthworms exposed to the exact ratio of herbicides present in Enlist Duo© had the same mortality rate as earthworms exposed to significantly higher amounts of either chemical alone. In other words, the formula proven so successful to kill tough broadleaf weeds and grasses may impact other soil life forms as well.
Making a Mark
Nicole and her co-researchers, Caitlin Lazurick and Rachel Owings, were employed full-time over the summer and part-time through the fall thanks to grants from South Carolina Independent Colleges and Universities (SCICU) and IDeA Networks of Biometical Research Excellence (INBRE). Their faculty sponsors were Dr. Edna Steele, Associate Professor of Biology and Dr. Jeff Brotherton, Associate Professor of Biochemistry.
The team presented to peers, faculty, and professionals in three regional science conferences over the academic year. Nicole’s poster won first place at the South Carolina Academy of Science Conference in March, 2017.