Background: This experiment is based in Berryville, Virginia - a rural town with a population of about 4,500.
My experiment aims to answer two questions, a) What type of container (width & depth) suits mosquito breeding best, and b) What type of bait suits mosquito breeding best (naturally vs artificially produced). My variables are as follows, container type - large bucket, safe bottle, and pie tin (changing the depth and width of containers), and bait type - grass clippings and cat food. The grass clippings are acting as a natural source of food/nutrients for the mosquitos, while the cat food acts as an artificially produced source of nutrients for the mosquitos.
To ensure that I am considering bait and container type for each trap, I have assigned two traps to each container type and one bait type to each of the two container types. For example, I have two large orange bucket traps. One trap is baited with grass clippings, and the other trap is baited with cat food. This same structure follows for the bottle and pie tin traps.
I have kept all other variables controlled - container color (for each container pair), water to container ratio (each is filled 3/4 with water), general placement of trap(shaded area and placed on the ground), bait to container ratio, and type of water (tap).
WEEK 1 - 20 June 2022
So far, I have completed one check on each trap. I have found that the large bucket baited with grass clippings has hosted the most mosquito larvae/eggs. I counted a total of 42 egg rafts and thousands of mosquito larvae in just one week! I was able to identify these larvae as those of the Culex species.
All traps baited with cat food have been found with many dead insects, flies, fly larvae, and even a slug! I am considering the situation that the cat food contains a food preservative that may be killing all of these insects. Thus, I do not expect the cat food baited traps to host many, if any, mosquito larvae. I am considering switching my bait to another artificial source that does not contain preservatives, especially since this experiment has only just begun.
Pictured are a few of my traps!
Here are some pictures of the egg rafts, young larvae, older larvae, and even adult mosquitos I have found in my large bucket trap baited with grass clippings! I've identified these larvae and mosquitos as Culex!
WEEK 2 - 27 June 2022
This week I completed my second mosquito trap check-in! The only trap that produced any mosquito larvae was, once again, my large bucket trap baited with grass clippings. This trap produced about the exact same amount of both larvae and eggs as it had the week prior. I counted a total of 45 egg 'sacs' and thousands of mosquito larvae (Culex)! However, this week, there were both large and small larvae. I was able to view the obvious size differences between the two larvae! I also found three adult mosquitos in this trap. I'm still not sure if these are mosquito females drowning in the bucket, or if they are hatched larvae unable to escape the bucket. I will have to look more into this.
My other traps that are still set up and collecting data are my pie-tin cat food and pie-tin grass clippings (this trap had naturally filled with rain water and is now up and running after having been disrupted last week!), my safe-bottle cat food, and by bucket cat food and bucket grass clipping traps. Each of the cat food traps, once again, had many dead bugs and even a slug. I did find fly larvae in the pie tin cat food trap this week.
I am hopeful that my pie-tin grass clippings trap will produce mosquito eggs and larvae within the next week.
WEEK 4 - 09 July 2022
I was unable to check my traps during week 3 because I was out of town all week. However, I did check my traps on July 8th and had absolutely amazing results! Normally, I would only find mosquito eggs, larvae, and adult mosquitos in my large bucket trap baited with grass clippings. But this past week I found mosquito eggs and larvae in four of my traps (the grass clippings pie tin, the cat food bottle trap, the cat food bucket trap, and the grass clippings bucket trap). One of my traps had been disturbed and the water and bait had been dumped out, but I moved that trap to a more remote location and plan on refilling it this weekend. Each of these traps hosted Culex pupae and mosquitos!
This week's check also brought up a lot of questions and possible experimental errors. My cat food bottle trap did have mosquito larvae and eggs in it, however, it also had leaves that had fallen into it that looked like they had been sitting in there for a while. So, I asked myself, are there mosquito larvae in this trap only because of the leaves that have been soaking in here? But then I also found mosquito larvae in my cat food bucket trap which did not have any leaves or greens in it! Nonetheless, I am still faced with the experimental error that I hadn't checked the traps in about two weeks... which differentiates from my regular weekly checks of traps.
WEEK 5 - 15 July 2022
This was my final week of Mosquito Trap checking and thus the final week of collecting data for my experiment. Once again, four of my traps produced Culex egg rafts, larvae, pupae, and adult mosquitos. Also, this week, I finally learned what a mosquito pupa is. I had seen them before in my collected samples but hadn't known they were a specific stage in the mosquito life cycle. Once again, my bucket traps produced the largest quantity of mosquito larvae.
a) What type of container (width & depth) promotes the most mosquito oviposition/breeding?
Based on my experimental results, I can conclude that in accordance with my location and the conditions under which my traps were placed, traps with a larger depth of water and width of water surface area promote the most mosquito oviposition/breeding. Each week, my data resulted in the large bucket traps producing tens of egg rafts and thousands of mosquito larvae, while the pie tin and bottle trap produced typically no more than 5 - 10 egg rafts and tens of mosquito larvae.
b) What type of bait (naturally vs artificially produced) promotes the most mosquito oviposition/breeding?
Based on my experimental results, I cannot strongly conclude which bait type promoted the most mosquito oviposition/breeding. From the start, the bucket trap baited with grass clippings produced thousands of mosquito larvae. However, none of the other traps were producing mosquito specimens until week 4, when all of the traps - both grass clipping and cat food baited - produced mosquito specimens. One interpretation I developed early into the experiment was that the cat food may have contained a food preservative that was killing all of the insects attracted to it, and thus was deterring away mosquitos. However, because the mosquitos eventually bred in both a cat food baited bucket trap and a cat food baited bottle trap, I think this interpretation is not applicable. Instead, I am curious as to whether the cat food floating on the water's surface of each trap was what was deterring mosquitos. With each week, I was removing dead bugs from both the cat food baited traps - so, each week I was also removing some of the cat food floating on the surface of each trap. By week 4, most of the surface floating cat food had been removed and all of a sudden mosquitos were breeding in the traps. Nonetheless, this is an experimental question I would have to observe further with a new experimental design and objective.
With most experiments, experimental errors that may skew data/results are introduced into the study. Though I attempted to control as many variables as possible and remain consistent with weekly trap checking, I do have a few experimental errors I would like to recognize.
a) Changing water levels in traps - As I checked traps, I would occasionally have to remove noticeable amounts of water from the traps as I removed mosquito larvae and pupae. With the large bucket traps, I would replace the lost water with new tap water. These two traps were placed in my backyard and thus I had easy accessibility to plumbing and water to refill these traps. My pie tin and bottle traps weren't always refilled with water after each trap check because of their more remote locations. Lowering the water levels of traps may have affected my data collection.
b) Precipitation - Some of my traps were placed under tree or infrastructure coverage which protected them from harsh precipitation, or really any precipitation at all. For those traps which did not have coverage from rain, such precipitation may have affected my data collection.
c) Foliage fallen into trap - My cat food safe bottle trap was found with foliage having fallen into and seeped in it during the week 4 check. This experimental error sufficiently affected my data collection in reference to concluding which bait type the mosquitos preferred more.
d) Moved/disrupted traps - A few of my traps were disrupted throughout the entirety of my experiment. Within the first week, my grass clipping bottle trap had been mowed over and my grass clipping pie tin had been moved. I was able to reset the pie tin trap and collect data from it later in the experiment. My cat food pie tin trap was also disrupted during week 4 when I had been recording mosquito specimens in each of the other traps.
Thank You for reading and learning about my NASA SEES 2022 Mosquito Habitat Mapping Experiment!
About the author: Julianna is a senior at Clarke County High School, Berryville, VA. This blog describes a mosquito trapping experiment conducted as part of the NASA STEM Enhancement in 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/).