Southeast Student Exploring Effects of Climate Change on Mosquitoes at Tyson Research Center


It’s that time of year when pesky mosquitoes can take a bite out of summer. But Southeast Missouri State University sophomore Delilah Sayer isn’t letting that deter her from learning more about the insect at Washington University’s Tyson Research Center where she’s examining climate change’s impact on parasite prevalence in mosquitoes’ and their ability to transmit disease.

Sayer, an environmental science major, policy and communication option, of St. Louis, Missouri, is spending her fourth summer at the Center, collecting data and conducting research on native and invasive mosquito species in the St. Louis area.

She began interning at the Center as a high school freshman, completing the week-long Shaw Institute for Field Training (SIFT) session. She returned her sophomore and junior years of high school for the Tyson Environmental Research Fellowship summer program. She completed her third summer at the Center last year following her freshman year at Southeast.

This summer, Sayer returns as a student fellow helping collect data as part of the Center’s study under Principal Investigator Dr. Kim A. Medley, director of the Center, on how climate change influences mosquitoes’ ability to transmit diseases that affect humans.

“I will get together containers, sieves, rain water and whatever else we need to go out into the field that day,” Sayer said. “Once field work is done, we come back to the lab and collect and process the data. There is always lab cleaning to do, such as cleaning lab wear. Along with this, we must also care for our mosquito colony by blood feeding them, changing the egg papers and changing the sugar water.”

Southeast student Delilah Sayer collects data for her independent study project at the Tyson Research Center.

Her contribution to the study will help Tyson researchers learn how native mosquitoes are affected by invasive mosquito species and the rising temperatures of climate change. Their findings can lead to a better understanding of how different species respond to environmental changes which could have vital applications for public health experts.

“My team is looking at how the predicted 3-degree Celsius temperature rise will affect the prevalence of parasites found in mosquitoes, and the more we can predict how the rising global temperatures will affect the spread of harmful diseases, the better we can prepare for them,” Sayer said.

As part of her fellowship, Sayer is also responsible for conducting and executing a personal project within the Center’s larger study.

“In the summer of 2016, I looked at whether or not native versus invasive plants affect mosquito larval development,” she said. “This was done by making leaf infusions with the native plants, such as blackberry and spicebush, and invasive plants, such as honeysuckle and multiflora rose.”

Because mosquitoes acquire their needed nutrients from the detritus of decomposing leaves, their larval growth is highly dependent on the accessibility of nutrients, Sayer explained. She discovered that of all of the plants she used in her experiment, honeysuckle and multiflora rose, carried the most larvae to adulthood.

“In the summer of 2017, I built upon the previous project but added the gregarine parasite, which is a free-floating parasite that inhabits the intestines of only invertebrates, in this case the Aedes triseriatus mosquito larvae,” she said. “We found that the previous high survival rate that was achieved with the honeysuckle was nonexistent once the parasite was added.”

Southeast student Delilah Sayer pipettes a spun-down gregarine solution for her independent study project at the Tyson Research Center.

This summer, Sayer is expanding her previous lab experiment under field conditions to see if the results acquired in the lab are repeatable in real life situations.

“I am trying to find alternative and natural ways to combat mosquito larvae survival rates that don’t negatively affect other animals, humans or the environment,” she said. “The hope is that when my experiment is done I will have found one possible avenue to more naturally kill mosquitoes through using a combination of plants and parasites that naturally occur in invertebrates.”

Working at the Tyson Research Center has given Sayer unique, real-world science research experiences in the field, while working one-on-one with experts who support and encourage her personal and professional growth.

“We are asked questions and our opinion of the work we are doing,” she said. “We are encouraged to help form ideas for projects and help troubleshoot inevitable problems. I also act as a mentor to the high school interns, and I offer them guidance. They often turn to us (college interns) with any immediate problems that they may have.”

Being part of a team at the Center is the best part of her internship.

“They make it so much more fun, and we always have awesome conversations,” she said. “We all get along so well, and I know that I can turn to any of them for advice. I know that without them, the everyday grind would be incredibly dull. Everyone looks out and cares for one another, and there is so much acceptance and lack of judgment. It is so incredible to be around like-minded people who share my same passion for helping other people and our planet. It is truly a one-of-a-kind place.”