by Sarai Acosta
If you pass through Kinwell Plaza, you may notice at the corner of Proctor Hall West a tray of jars that just look like dirty water. You may be thinking, like a worried parent in the summer, “That water is a breeding ground for mosquitoes,” and you’d be right, it sure is. The jars in Kinwell Plaza are for a research project being conducted by GC alumna, Carly Uhlir, who graduated this past summer. When she realized that her plans at GC were cut short because of the COVID-19 pandemic, she reached out to Dr. Sandra Cooke, Assistant Professor of Biology and Director of Supplemental Instruction here at GC, for an opportunity.
In the fall semester of 2021, Dr. Cooke taught BIO 3490, Aquatic Ecology and Lab. For a project in that class, she piloted the very first mosquito study in Kinwell Plaza. The purpose of this study was to observe the egg-laying behavior of mosquitoes, and whether they preferred clear tap water or water that had leaves or other dissolved organic matter (DOM) in it, making it brown and murky. The study was also conducted to prove the fact that female mosquitoes better prefer DOM water to protect their eggs and larvae from the UV radiation of the sun, since the darker water would work as a type of “sunscreen” for the larvae. Unfortunately, this first study was unsuccessful because of the overfeeding of the experiment. The class would add fish food to the jars to feed the larvae, but too much of it left a film of residue over the water, preventing the larvae from getting oxygen, and so they died off, ending the pilot trial. Then, Uhlir rekindled the project.
From July 7 to Aug.11, 2022, Uhlir conducted her first mosquito study trial, searching for the same results as Dr. Cooke’s class, but also researching how certain mosquitoes may prefer different types of water, whether it be regular tap water or DOM water. The DOM water was made by soaking 10 grams of oak tree leaves from GC’s front campus lawn in 800 mL of tap water for almost two days, then vacuum filtering it and adding tap water to dilute it to 25 percent DOM and 75 percent tap water.
On the first day, she placed 12 containers with water, six clear and six DOM, out in Kinwell Plaza. Before placing them outside, though, she made sure to check the pH of the water, as well as its absorption (the brownness) of the water, to take note of what the mosquitoes might prefer. Checking in on them every two to three days, Uhlir encountered some challenges.
The summer’s unpredictable weather knocked over the containers, overfilled them and even evaporated the water with extreme heat. She didn’t want to interfere with the containers too much and risk the trial, but keeping them regulated and taken care of was essential to keep it going. However, those challenges didn’t stop Uhlir from getting the results she needed.
On July 28 she found that two of the containers had larvae. Container No. 3 had hatched 12 larvae, while No. 5 had just hatched one, but the concluding factor is that both of these containers were of DOM water, not the clear tap. Now the next step was to monitor it almost daily, watching them grow from larvae to pupa, and making sure that the pupa would not reach adulthood before Uhlir could put an emergence chamber on the containers, catching the adult mosquitoes so that she could ID them and see what species they were.
By the fourth week of the trial, Uhlir had 13 adult mosquitoes from her study. To properly ID them, she put them in a freezer for about an hour to kill them, then see what mosquito species they were by looking through a microscope. The mosquitoes were identified as the Asian tiger mosquitoes (aedes albopictus), which is an invasive species in America. This species of mosquito prefers to lay its eggs in stagnate pools of water, which is why they found Uhlir’s containers to be a perfect nesting spot. Unfortunately, they can also carry diseases like yellow fever and dengue fever.
Uhlir’s second trial started Aug. 23, and she plans to end it around Sept. 23. These results that she is collecting are important to know where to find mosquitoes and track their migration and breeding patterns.
Uhlir gives a huge thanks to Dr. Cooke, who was a great mentor to her and gave her the ability to use lab equipment even after she had graduated. She also plans to present the results from her trial to the Association of South-Eastern Biologists.