Experiment 1:
For my first experiment, I tested the effects of water color on mosquito oviposition.
Materials:
- Three 1.25-liter bottles
- Three bottles of food coloring (yellow, green, and blue)
- Three rocks
- Three paint stirring sticks
- Nine dog treat pebbles
- Three cups of water
Experimental Design:
After reading articles such as "New Study Shows Mosquitoes are Attracted to Specific Colors," I decided to focus on setting water color as a variable in my experiment. I used three identical plastic 1.25-liter bottles to create the trap, cutting each one in half and taping the neck of the bottle upside down. Next, I added 1 cup of water to each container, before stirring 3 drops of differing food colorings into the water with a paint stirring stick. The three colors I chose were yellow, green, and blue. I made these specific choices because the previously mentioned article stated that mosquitoes were more attracted to warmer colors (such as red and yellow) than cooler ones (such as green and blue). If I were to repeat the experiment, I would add a red-colored variable. After this step, I placed three rocks of similar size at the bottom of the container in order to prevent errors such as the containers being blown over. Finally, I utilized 3 dog treat pebbles as bait in each container, leaving them to float in the water. The three traps were then placed within proximity to each other on a table in the sunlight. The initial setup can be seen below.
Results
Over the next week, I continuously checked my trap for mosquito larvae, but they didn't produce any results. In fact, there were no bugs in the water at all. However, I do not think that this was due to the color variables used. The area that I live in and placed my AOI points is very dry, and I have very rarely seen mosquitoes at all. For my next experiment, I will most likely move my traps to my front yard, where there has been slightly higher interest in the past.
Despite the disappointing lack of results, my traps did change over the course of the week. The water became noticeably murkier, likely as a result of the the dog treats dissolving. What was interesting to me was that the treats dissolved in different ways and at different rates. As depicted in the following images, the bait in the green and yellow traps simply dissolved into white flecks. However, in the yellow trap, the bait instead transitioned into a papery substance, which released a noticeably stronger odor compared to the other traps. Additionally, the blue container was the only trap to change colors, transitioning to a more turquoise green. These observations helped me to realize that the food colorings are composed of different substances that might affect the results of the experiment.
I will reset the traps and continue to monitor them in the following week.
Experiment 2:
For my second experiment, I tested the effects of trap position in shade versus sunlight on mosquito oviposition.
- Four 1.25-liter bottles
- Four rocks
- Twelve dog treat pebbles
- Four cups of water
Following the lack of results (no presence of any mosquitoes or larvae) of my first experiment, I decided to focus on another variable in hopes of attracting more mosquitoes. This time, I tested the affects of variations in natural shade on mosquito oviposition. I used four plastic 1.25 liter-bottles to assemble the traps identically to the last experiment. However, for this experiment I did not use any food coloring, instead leaving the water clear and transparent. After this, I placed one bottle on a platform where it would be in the sun without cover all day, and two bottles in locations underneath a leafy hedge where they would be in shade all day. For the final bottle, I utilized it as a control by placing it in my yard, where it would be in the shade approximately half of the day and sun approximately half of the day. The pictures of the locations can be seen below. I monitored and checked in on these traps every five days.
Initial Trap in Sunlight:
Initial Traps in Shade:
Initial Control Trap (partial shade-partial sunlight):
Over 5 days, I continuously checked my trap for mosquito larvae, but once again I did not find any. However this time, there was a noticeable increase in bug activity, especially in the two shaded traps and the one partially shaded trap. In these instances, I observed spiders, bees, and flies crawling along the inside of the trap, but never really touching the water. Only once did I see a mosquito in one of the fully shaded traps, but it was floating dead in the water. It did not appear to lay any eggs. From this, I can infer that insects prefer traps that are positioned underneath a naturally shaded environment, as they may create more suitable breeding habitats for oviposition and larvae growth. Like the last experiment, the trap water became noticeably murkier as the dog food pebbles dissolved. Without the variation in water food coloring, however, there was very little deviation in the amount of time this dissolution took. For my next experiment, I will place all of my traps in shaded areas to maximize results, but this time I will be assessing the affects of different baits on mosquito density.
Final Trap in Sunlight:
Final Traps in Shade:
Final Control Trap (partial shade-partial sunlight):
Experiment 3:
For my third and final experiment, I tested the effects of differing bait variables on mosquito oviposition.
- Apple skin peels
- Sweet potato peels
- Potato peels
After receiving little results from my second experiment, I decided to test the efficacy of different baits with the thought that perhaps the previously-used dog pebbles weren't attractive to insects. For the duration of this experiment, I continued to use four plastic 1.25-liter water bottles filled with water. Like my second experiment, the water inside the bottles was kept clear and transparent, without food coloring. However, this time I utilized a handful of skin peels from varying produces in the place of the dog pebbles. One bottle contained apple skin peels, while another housed sweet potato peels and potato peels were placed in a third. Meanwhile, my control bottle contained all three types of peels (apple, sweet potato, and potato). Since my second experiment demonstrated a higher level of insect activity in a location of natural shade, I placed all four bottles spaced apart in the shade underneath a hedge. The pictures of each bottle can be seen below. I monitored and checked in on these traps every five days.
Initial Traps:
Initial Apple Trap:
Initial Sweet Potato Trap:
Initial Potato Trap:
Initial Control Trap:
When I checked the traps there were not any adult insects or larvae (dead or alive) inside any of them, unlike my second experiment. Like the last two experiments, the bait in the traps showed signs of deteriorating, and the water became noticeably murkier over time. In this experiment, however, the final traps were not nearly as murky or debris-filled, likely due to the change to more organic baits. From my lack of results, I can gather that organic bait may not have the same appeal to insects as more processed options, such as dog pebbles. The final traps can be seen below.
Final Apple Trap:
Final Sweet Potato Trap:
Final Potato Trap:
Final Control Trap:
Conclusion:
Through three separate experiments that tested the effects of a different variables on mosquito oviposition, I gathered little results. This was likely due to the dry nature of my testing location in San Diego, which was not an attractive option for mosquito breeding and oviposition. Despite the disappointing lack of larvae, I still learned a lot about the experimental design process and insect preferences in my pursuits. In my first experiment, for example, the baits inside the traps degraded at differing speeds due to different food colorings being used in each one. From this, I learned that even slight variations could drastically affect the experiment, and that I should maintain a control variable to lower this source of error. My second experiment proved the most fruitful, as from it I learned that insects are more attracted to potential breeding locations in naturally shaded areas (such as hedges and trees). Due to this discovery, this experiment exhibited interest from bees, and one trap even contained a dead mosquito at one point. For my third and final experiment, I established that the lack of interest was likely not due to my choice of trap (although that is not to say it did not have an effect), as there was less insect interest than the second experiment. However, my data for this trial was limited, as I was out of town for a couple of days and not able to actively observe the traps.
About the author: Benjamin is a junior at Francis Parker High School in California. 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 U.S .high school (http://www.tsgc.utexas.edu/sees-internship/). He shares his experience observing his mosquito breeding-habitat traps in San Diego, CA, in this guest blog post.
