SEES 2022: Oviposition Investigation

Guest blog: Ryan Dempsey

Research Questions: My experiment ran two adjacent triads of mosquito traps aimed to explore two questions: whether the local mosquito species in my area prefer to oviposit in containers with greater surface areas of water, and whether the same mosquitoes would prefer to oviposit in particular containers with varying types of water "bait". 

Data: After 5 weeks of running this experiment, I failed to capture even a single mosquito larva. I'll go into further depth as to why this might've been later on in the "Conclusion" section. Both experiments suffered from a couple of experimental errors, and overall I've learned tactics for setting up more precise and potentially successful experiments for whatever research I might conduct in the future.   

I've set up 6 traps in my backyard. 3 traps will measure differences in surface area (8.3"^2 vs 16"^2 vs 21"^2), and the three other traps will test bait preference (tap water vs muddy water vs sweet water).

^Surface area containers, some supported by small rocks to keep steady.

^Bait comparisons. Notice the tape on the popsicle sticks. This was to extend the oviposition space that the Aedes genera have access to. Before, the sticks were barely above the water line, so I felt like this was a necessary change. Having such little space during the beginning might've played a role in seeing no results, but other factors most likely contributed to my lack of results too.  

RESULTS: Throughout all 5 weeks, the surface area experiment seemingly had no contact with any noticeable lifeforms apart from one exception. However, the bait experiment, more specifically the sweet water, was teeming with different bugs (none of which were mosquitoes though) See below:

I saw many ants, alive and dead, along with three small snails. The week after resetting the trap, I noticed no snails, but now rather a couple of flies, alive and dead.

In the tap water cup, I thought I saw a juvenile mosquito, but on closer inspection that seemed incorrect. I took it out of the water and looked at it under the portable microscope:

With the help of some internet forums, I concluded that it's either an ant or a wasp.

Dead wasp that I found in A2, I was able to observe it closer with the clip-on microscope, which was very interesting to inspect!

Conclusion Part 1: I might attribute some of my difficulties to a few factors below:

  • Evaporation of water due to intense rise in heat (at least in the surface area containers which weren't covered in heat). Also, because of a week long absence, I couldn't collect data during one of my intended time slots, which gave more time for the traps to evaporate all of their water supplies. This might also be due to an experimental error that I was unaware of while I was away, as each trap was surprisingly dead-dry, something I hadn't noticed during regular interval observances. 

Notice the dry containers

  • There might exist a superior breeding site in my adjacent neighbor's backyard. From what I can hear, they have a reasonably sizable fountain/feeder, which could prove to be a more attractive breeding ground for mosquitoes. This also might be a reasonable assumption because from what I recall, we (setting of my experiments) rarely experience mosquitoes in our backyard, even during peak mosquito season (although my vague memory shouldn't be concrete evidence of this hypothesis). 
  • Balance troubles with the smaller traps and fight for "real estate" in the sweet water trap.

Conclusion Part 2: Even though I wasn't able to answer my research questions, I felt like I grew as a novice scientist during this experiment. This was the first citizen science experiment that I've done, so I basically had no experience when it came to devising an experiment like this. I learned that I need to have a more structured plan, and how I need to account for lots of major variables that might affect data collection. Many times the smaller water bait traps would either be partially or fully tipped-over, which restricted data collection. This was also relevant with the limited oviposition surfaces for the same traps (the Popsicle sticks). I had to adapt, but this was in the middle of the experiment, so any data collection past the date of adaption couldn't be used in trends before said date. I really felt like I learned from all those little problems that I faced, and I now know how I would devise a better trap, and experiment in general, for a future research study. 

​​​​​​​About the author: Ryan is a student in Austin, TX. This blog describes a mosquito trapping Ryan Dempseyexperiment conducted as part of the NASA STEM Enhancement in Earth Sciences (SEES) summer 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 ( Ryan shared his experience this summer in this blog post.

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