Hypothesis: It is expected that most mosquito larvae will be present in alkaline water with the highest pH while the least mosquito larvae in the acidic water with low pH.
Setup: 5 identical buckets were placed in a shaded area in my backyard, several meters from each other. The independent variable in this case was the pH of the water as it varied from strongly acidic to strongly alkaline. The exact values of pH used were 1, 3, 7, 10 and 12. These were achieved by adding baking soda and lemon to 500ml of distilled water. The number of larvae were observed every 5 days after which the water was disposed and replaced.
Method:
1. Pour 500ml of distilled water into each of the 5 containers (measured using a measuring cylinder)
2. Add baking soda to corresponding traps until pH of 10 and 12 is reached
3. Add squeezed lemon to corresponding traps until pH of 3 and 1 is reached
4. Use pH universal indicator paper to identify when the liquid has reached the desired values
5. Keep one of the traps neutral (pH 7)
6. Label the trap containers (as seen in the picture above)
7. Place the traps approximately 150cm apart from each other in a shaded area
8. Place a rock into each of the traps
9. Collect data every 5 days and photograph mosquito larvae
10. After every observation replace the liquids in the containers
Observations:
Week 1 (24/06/22)
So far the experiment has shown that the higher the pH, the more larvae observed, therefore the most larvae were recorded in the bucket with pH of 12 while the least in the bucket with pH 1. Additionally in buckets with pH 1 and 3, or in other words the acidic ones, mold was formed on the surface.
Week 2 (01/07/22)
This week the temperatures were extremely high (on average 34℃) which resulted in majority of the water evaporating. Initially there was 500ml of water in each of the buckets but after 5 days there was only around 150ml, slightly varying in each of the traps. Due to this, the overall mosquito count was much lower than during week 1. The hypothesis that the most larvae will be found in the most alkaline environment was proven again, however this time, the most alkaline environment recoded only 4 larvae. Additionally, there were a lot of other animals such as ants, bees, flies etc. found in all of the traps.
In the trap with pH 3, there was a pinkish layer formed at the surface which prevented me from making any count of the larvae
Week 3 (08/07/22)
This week there were heavy rains and I did not manage to save the traps in any form and therefore the result of mosquito larvae in all traps is 0. The solutions prepared in corresponding traps based on pH overflowed due to rain water.
Week 4 (14/07/22)
Once more my hypothesis was proven as 7 mosquito larvae were were in the trap with pH 12 while none were detected in the trap with pH 1. Once again some of the water has evaporated because of high temperatures and exposure to sunlight, however the results are still close to the ones from week 1 where the traps were in complete shade. This time however, there was a considerable amount of ants found in all the traps, which can most probably just be explained by a new anthill forming nearby or something similar.
Conclusion:
Over the course of 4 weeks, 5 mosquito traps were placed approximated 150cm from each other and were observed in 5 day intervals. The independent variable in this experiment was the pH which was varied by using lemon and baking soda and therefore reaching the pH values of 1, 3, 7, 10 and 12. The data shown above proves the hypothesis as the higher the pH, the more mosquito larvae could be found the trap. This remained true throughout all the 4 weeks, however this is too little of a time frame to come up with a set conclusion. In reality we only have 3 valid data points for all the traps as during week 3 all the traps were all destroyed by heavy rain and from the trap with pH 3 we have only 2 weeks of valid data. Therefore, observations over a longer period of time are required to prove the hypothesis with certainty.
About the author: Adriana is a junior at Galileo High School, Bratislava, Slovakia. 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/). Adriana shares her experience this summer through this blog post.
