Introduction
To follow along with NASA GLOBE’s mission to encourage public involvement in mosquito observation research, I decided to conduct a small experiment to determine preferred mosquito habitats. I’m writing this blog about my experience to encourage people to become citizen scientists as well and take part in the GLOBE Observer App’s mission [1]!
Hypothesis
Since mosquitos most commonly breed in swamps or marshes and are said to thrive in water that is fairly shallow, filled with organic matter, and nutrient-rich [2] [3], I hypothesize that mosquitos will be most abundant in the container with 1-inch of pond water.
Experimental Iterations
In the first experimental iteration, my setup was as follows: I took 6 containers. Two containers were filled with 1 inch of water, two were filled with 2 inches of water, and two were filled with three inches of water. I placed grass and dirt into one of the 1-inch, 2-inch, and 3-inch full containers, and plain tap water into the other three containers at the same depths. However, this experiment ran into some problems. I realized that even though I was adding organic matter to my water, it wasn’t truly a true simulation of a natural water source, as I had hoped for. Therefore, instead of adding vegetation and dirt to my water, I decided to collect some from a pond near me to use in my experiment. I checked the water thoroughly to ensure there were no mosquito larvae or eggs already present in the water before the experiment began. In addition, I realized I was using clay pots that had cracks and putting in way too much dirt, both of which lowered the water level. Therefore, I decided to use a glass container for the next version of the experiment. Glass was chosen instead of plastic to ensure the traps did not tip over and spill out their contents due to strong winds. Furthermore, my tap water traps were also filled with leaves, dirt, and grass from the surrounding trees and lawn. Therefore, I decided to place the clear tap water traps on my porch, which is roofed.
The second iteration of the experiment implemented the aforementioned changes based on the issues encountered in the first experiment. However, this version of the experiment also ran into some challenges. About a week into my redone experiment, without much warning, there were heavy rains in the area. My pond water traps were rendered unusable, as the water levels were now altered, along with the original water composition and any accumulated mosquito larvae. Therefore, I decided to place the pond water traps onto my porch alongside the clear tap water traps as well. I also reduced the number of traps in order to better focus on maintaining the traps I used, and adjusted the water levels so that I could still draw conclusions from the results. I then restarted the experiment to maintain consistency between the tap water and pond water traps.
The final experiment made the improvements from the first two versions of my experiment and is detailed in the following section.
Final Experimental Setup
For my experiment, I am taking four identical glass containers. Two containers will be filled with one inch of water and two will be filled with six inches of water. I am placing water from a nearby pond into one of the 1-inch and 6-inch full containers. The pond water is thoroughly examined to make sure no mosquitos, mosquito larvae, or eggs were already present before the start of the experiment. The other 1-inch and 6-inch full containers will contain regular tap water as a control. Each of the traps was placed 8 feet apart from the closest other trap, and all traps were located on my back porch. Observing the differences in the number of mosquitos present in each container will give insight into the mosquito's preferred habitat.
Pond from which I am getting the water for my traps:
Close-up surface view of the pond:
My traps before starting the experiment. Note the differences in color, turbidity, and presence of organic matter among the containers with water from the pond vs from the tap:
Results
After the three-week duration of the experiment, the traps were brought back inside and checked for mosquitos, mosquito larvae, or mosquito eggs. All organisms contained in the pond water were removed and examined under a clip-on microscope.
No mosquitos, mosquito larvae, or mosquito eggs were found in any of the traps. However, a lot of other insects, both dead and alive, were found in the traps.
Picture of me looking at a drop of pond water under the microscope to capture an image of a fly in the water (I’m using a makeshift microscope slide - the bottom of a glass bottle! - for my first observation in the field):
Discussion
The area I live in has quite a few mosquitos, which begs the question of why my traps were unsuccessful at housing any mosquito larvae.
A likely reason there were not any mosquito larvae found in my pond water is the presence of damselfly nymphs, pictured through my microscope in the image below. These insects were also observed in the pond water when it was initially sampled. Damselfly nymphs are voracious predators and consume both mosquitos and mosquito larvae. Therefore, the abundant presence of these critters in the pond water likely made it an unfavorable mosquito breeding habitat.
Another probable reason as to why there were no larvae found likely has to do with the location of the traps. In order to keep the tap water traps free of any falling vegetation and debris, and to ensure none of the traps were compromised due to the regular thunderstorms in this area, I had to keep these traps under the gable roof on my porch. Though this helped ensure the traps remained standing and the water levels and types were not compromised, it limited access to mosquitos.
Conclusions
The results of this experiment were inconclusive since no mosquito larvae were found due to confounding factors. However, I had a great time throughout this process. From this experience, I learned a lot about the process of research, mosquitos, and environmental science. I also found some very cool creatures along the way, such as this freaky one that I believe to be a caddisfly larva or a segmented worm: https://youtube.com/shorts/nORTbkEkUf4.
Hopefully, all of you reading this will download the GLOBE app and get involved in our mission to map mosquito habitats!
References:
[1] https://observer.globe.gov/about/get-the-app
[2] https://www3.epa.gov/npdes/pubs/sw_wnv.pdf
[3] https://phys.org/news/2020-11-nutrient-rich-heaven-disease-spreading-mosquitoes.html
About the author: Jay is a student at Green Hope High School in Cary, NC. This blog describes a mosquito trapping experiment conducted as part of the NASA STEM Enhancement in the Earth Sciences (SEES) high school research internship. His virtual internship is part of a collaboration between the Institute for Global Environmental Strategies (IGES) and the NASA Texas Space Grant Consortium (TSGC) to extend the TSGC Summer Enhancement in Earth Science (SEES) internship for US high school (http://www.tsgc.utexas.edu/sees-internship/). Jay shares his experience in this blog post.
