Purpose
The purpose of this experiment is to determine the prevalence of two characteristics of containers in attracting more mosquitos. I wanted to measure if mosquitos prefer to lay their eggs in locations with more shade as well as how the color of the trap, dark or clear, can also impact this preference.
Methods
Since Aedes mosquitos, which are the most common type of mosquitos in San Diego County, tend to prefer containers with larger openings, I used such dishes to create my traps. Out of the three traps, I use a fully clear container for one and black containers for the other two.
In order to ensure a proper set of controls, I filled each trap with the exact same bait. I used some rocks to hold down my traps along with grass and dried leaves. To maximize my consistency, I also made sure to use the same amount of bait in each container and approximately the same amount of water.
I placed the clear trap and one of the black traps in a mostly covered location to give them more shade. On the other hand, I placed the second black trap in a location that was slightly less covered and more exposed to the sun throughout the day.
Due to the current hot climate in San Diego, I had to periodically visit my traps close to every 2 days to specifically check the water levels, especially for the trap in the sun.
I checked my traps weekly by bringing them out of their original location and isolating interesting samples of the water into a separate dish to then observe with the magnifier. After making my observations, I refilled the water as needed and returned the traps to their original location.
Results
By the end of the 6 weeks of my experiment, I was unable to find any mosquito larvae in any of my 3 traps. In the dark-colored trap in the shade, though, I was able to find a non-mosquito larva and an insect similar to, but not exactly, an adult mosquito along with many other small to medium-sized insects. The dark-colored trap in the sun also attracted many similarly sized insects, some of which had wings and a few that were spiders. The clear trap, though, had a very opposite result with only a few extremely small insects and spiders.
Trap 1:
Week 4:
Week 6:
Trap 2:
Week 5:
Trap 3:
Potential Causes of Errors
Taking into consideration the hotter climate in San Diego during the summer, I had to the traps in an area closer to my house so that it was easy for me to monitor the water levels and refill them as needed. Since the traps were therefore within a residential area, the use of bug and mosquito repellents may have caused there to be no mosquito larvae in my traps.
During my experiment, there were also multiple times when a trap lost water, most likely due to evaporation. To decrease this issue, I checked my traps every few days to refill the water up to a certain line. In the summer, San Diego, though, is significantly hotter during the day but can become much colder during the night. Although I excepted the water levels to decrease in the trap placed in more sunlight, there was a significant decrease in water levels in the shaded traps during the last two weeks of my experiment. This was most likely due to the increase in temperature in my community that occurred during those weeks. This error could have made it harder for mosquitos to be attracted to the traps as the water levels kept decreasing.
Conclusion
A final conclusion of how the darkness of a trap or the amount of shade impacts mosquito oviposition cannot be made since no mosquito larvae were found in any of the three traps.
The observations of other insects and larvae found in the traps do suggest a general trend of insects, though. The two dark-colored traps had a vastly greater amount of insects in them that were also of larger size compared to those found in the clear trap. Furthermore, between the two dark-colored traps, the one in the shade also had a larva and insects more similar to mosquitos. This suggests that there may be a trend of insects preferring darker and shadier bodies of stagnant water to go to and lay their eggs in. More experiments would have to be conducted, though, to find a definite relationship between these factors.
About the author: Samhithais a rising senior at Del Norte High School, San Diego, CA. This blog describes a mosquito trapping experiment conducted as part of the NASA STEM Enhancement in the Earth Sciences (SEES) summer high school research internship. Her 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/).
