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Hathcock and Niland examine invasive bug’s heat tolerance

By Luanne Williams

An invasive species from the Eastern hemisphere, kudzu bugs have made their home in the Southeastern U.S. since 2009. They landed on Ethan Hathcock’s radar this summer when he began a research project with biology professor Dr. Erika Niland.

A senior in pursuit of degrees in biology and history on his way to pharmacy school, Hathcock found himself armed with a net and wading into huge patches of kudzu along U.S. 74 to bring the tiny megacopta cribraria back to the lab. There he waded into a number of laboratory practices that were new to him but necessary to answer his research question: At what temperatures do kudzu bugs begin to experience stress?

In the study proposal that earned Hathcock and Niland a $1,600 Reeves Summer Research grant, Niland wrote that, as a way of monitoring the bugs’ thermal stress limits, she and Hathcock would determine whether molecular “heat shock proteins” were present in the bugs. These proteins protect cells from disease and damage caused by extreme heat.

“Previous research has shown that colder temperatures, parasites, and pathogens have reduced [kudzu-bug] populations, but we are unsure what temperature ranges cause stress,” Niland says.

Southern summers are notoriously hot. If the kudzu bugs have adapted to the Carolina heat, can they also adapt to colder temperatures, and what does that mean for their potential spread across the country?

“Our southern summer is warmer than what the bugs are in, in their native China, so we’re wondering if they have started to acclimate to our summers over the last five to 10 years,” Hathcock says. “Also, if these bugs are going to get more acclimated to colder temperatures, their ability to move across the U.S. is more likely.”

Closer to home, knowing how active the bugs will be in various temperatures can help forecast whether they will cause problems for soybean growers. “Although they prefer kudzu, they can feed on any legume,” Niland says.

Kudzu bug in petri dish with kudzu leaf

To test the bugs’ reactions to various temperatures, Hathcock and Niland would bring their day’s catch into the lab and let them acclimate for 24 to 48 hours before putting 10 bugs into each of three petri dishes and then exposing all three dishes to the same new temperature. Over the course of the summer, they tested eight batches of bugs at eight different temperatures ranging from 23 to 98 degrees Fahrenheit.

“At the colder temperatures, they would die off quickly, often within 30 minutes,” Hathcock said. “In the warmer ranges, they were a lot more active and were still alive at the end of the exposure.”

To determine at exactly what temperatures the bugs started producing stress proteins, the researchers removed the bugs’ legs, ground them up and began a series of protein extraction techniques.

Once the heat shock proteins were extracted, there was still the matter of measuring how much of the proteins the bugs were producing, which would tell Niland and Hathcock how much stress they were under. To do this, they had to create a western blot, a cumbersome protein-detection technique, for each experiment.

Although they were able to see the presence of the protein at higher temperatures, they are still nailing down the precise measurements by continuing to work on the blots this fall.

“To really master western blots takes a lot of practice,” Niland says.

“It’s a very detailed process,” Hathcock says. “You start with creating your gels to put your sample in. Eventually, you transfer the proteins to the blot, and once it’s on the paper it has to sit overnight. Antibodies attach to the proteins. Without them, you wouldn’t be able to see your proteins.”

The last step is using a camera scanner that takes 12 minutes to photograph the blot. Then a computer program is used to analyze the scans to determine the concentration.

If any step in the process goes awry, the troubleshooting can take hours, if not days.

Wingate student Ethan Hathcock works in the lab.

“Research involves a lot of trial and error,” Hathcock says. “When you are doing an experiment in a class that is laid out for you, normally things don’t go wrong, but with real research you are  in unknown territory, trying to figure it out for yourself.”

In addition to understanding how to troubleshoot procedures and isolate variables, Hathcock says the research will give him practice in presenting his findings, which he expects to do at Wingate’s Wellspring Symposium this coming spring.

“Being able to analyze and present the data will help me later as a pharmacist,” he says. “Plus, the research into invertebrates could open the door to other possibilities.”

Hathcock sought out the opportunity to work with Niland, who is his faculty advisor. 

“I first met Dr. Niland while attending a freshman invitation-only summer experience called BIOS,” he says. “I got to know Dr. Niland and couldn’t wait to work with her to achieve a common goal.”

Niland and Hathcock make up one of six faculty-student teams who received 2021 Reeves Summer Research grants.

Nov. 8, 2021