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1 Feeding Preferences of Pill Bugs When Given a Choice in Lighting Laboratory 2, Biology 183 001C Kayla Harrower Abstract The amount of light in a given area can affect where a pill bug would choose to eat. The purpose of this experiment was to test the hypothesis that the Armadillidium vulgare, pill bugs, would choose a dark environment similar to where they eat in nature. The experiment was designed with the given materials to best replicate the pill bugs natural environment. A dark and light side in a choice chamber was created, and each side contained a small amount of lettuce so that the pill bugs’ preference could be observed and recorded. After observing each trial group for ten minutes and recording which side the pill bugs chose to eat, the data shown did not support the original hypothesis. Six of the ten pill bugs chose not to eat at all, two were observed eating on the light side, and two were observed eating on the dark side. The original hypothesis had a solid foundation to begin with, but the execution of the experiment had too many errors to display accurate and successful results. It was apparent after the experiment that when testing an animal’s behavior, the experiment area should be as similar as possible to their natural environment to reflect the pill bugs’ behavior in nature. Introduction In this lab, the goal was to explore feeding and social behaviors of the pill bug, or Armadillidium vulgare. Before planning the experiment, it was read in the lab manual that pill bugs are commonly found in damp and decaying plant matter, and they tend to eat decomposing plants and animals at night (Anue et al. 2020). In an experiment by Joanne Tuck and Mark Hassall, pill bugs were observed spending a long time exploring their environment before eating (Tuck J. and Hassall M 2014). These statements led to question if a pill bug had a true preference of feeding in the dark versus in the light. Answering this question would give more insight to pill bug feeding behaviors, as well as social behaviors when observing how the pill bugs feed together. The findings of this experiment will help future researchers by showing if the environment a pill bug is in really affects its behavior and activity. This information would ensure that future experiments can be completed with the most success. Another significant

2 purpose of this experiment is to help understand ecological wellness. Armadillidium vulgare are an important part of an ecosystem because they assist in the process of breaking down decaying matter. If pill bugs are not behaving normally in this environment, the whole ecosystem would be affected. Based on the information read in the lab manual on pill bug feeding behavior, it was hypothesized that pill bugs will show a preference of eating plant matter in a dark environment over a light environment. Methods This experiment took place at North Carolina State University on September 10th, 2019. To begin the experiment, ten pill bugs were gently taken from the original container and placed into one petri dish at the lab station. A choice chamber was prepared for the experiment with four dimming sheets covering one side to replicate the dark environment where pill bugs are normally found. The four layers of dimming sheets over one side of the choice chamber act as the predicted preferred side, and the other half and the center portion were left uncovered. Placing the dimming sheets under the lid of the choice chamber keeps the sheets in place better than trying to balance them on top. On both sides of the choice chamber, an equal amount of lettuce was added to attract the pill bugs to making a choice of the light or dark side. Once the choice chamber was set up with the dimming sheets and the lettuce, two pill bugs were gently placed together into the center of the choice chamber. Two pill bugs were used instead of one because pill bugs are known to move in a small pack and prefer to be with other pill bugs. When any of the pill bugs got stuck on their backs when being put in the choice chamber, they were gently assisted to an upright position before continuing with observations. After the first two pill bugs were placed into the choice chamber, a ten-minute timer was started to observe each group for equal amounts of time. During the ten-minute period, the behaviors of

3 the pill bugs were observed, paying close attention to which side each of the pill bugs chose to eat in. These results were recorded in the lab manual using tally marks. Once the timer was up and the results were recorded, the two pill bugs were removed from the choice chamber and put into a second petri dish with a piece of lettuce. This was important in order to keep track of which subjects were already observed. This process was repeated with each pair of pill bugs in a total of five trials. Once all the trials were completed, the pill bugs were returned safely to the original container they were selected from, and the lab area was cleaned. Results Overall, the data found in the experiment did not support the original hypothesis. It was observed that many of the pill bugs chose a side fairly quickly, but they would not eat the lettuce on that side. The data showed that six of the ten subjects chose a side but did not eat, two subjects chose to eat the lettuce in the dark side, and two subjects chose to eat the lettuce in the light side. A graph was created to represent the data found in the experiment to give a visual representation of what was observed. The graph shows that a majority of the pill bugs chose not to eat in any of the given controlled environments that were set up. The orange bar represents the six bugs that did not eat. The red and blue bars show that the number of pill bugs that ate the lettuce in the light side of the choice chamber is equal to the number of bugs that chose to eat in the dark. (Figure 1.) Figure 1.

4 Discussion After evaluating the data from the experiment, it was apparent that the results found do not support the original hypothesis. The fact that most of the pill bugs chose not to eat and spent an equal amount of time in both sides shows that the pill bugs did not have a preference of eating in the dark versus the light. In order to support the hypothesis, the data would have needed to show that the majority of the pill bugs chose to eat the lettuce in the dark side of the chamber, when in reality, most of the pill bugs chose not to eat at all. Every pill bug that was observed was seen walking back and forth between the light and dark side exploring the choice chamber. The bugs that stayed on the light side and didn’t eat were seen hiding underneath the lettuce out of the light. Another important piece of information that was observed when executing this experiment was that once all of the pill bugs had been observed in the choice chamber and placed into the second petri dish, they all were seen eating the lettuce. This led to the conclusion that pill bugs prefer to eat as a group, and that their social behaviors greatly influence their feeding behaviors. If this experiment was to be attempted again, it would be important to place all ten of the pill bugs into the choice chamber at once and observe if they all choose to go to one side together. Another suggestion to make this experiment more successful would be to use decaying organic matter that could be found in their environment instead of fresh lettuce to better replicate their natural food preference. In the previously mentioned experiment by Joanne Tuck and Mark Hassall, they similarly observed the pill bugs spending a lot of time exploring instead of eating right away (Tuck J. and Hassall M. 2014). Another modification that would produce more accurate data would be to better replicate the natural environment of a pill bug by adding moist soil, decaying plants, and many other pill bugs, similar to what was explained in the lab manual

5 (Anue et al. 2020). This experiment should be repeated with the appropriate suggestions to retest the hypothesis. Conclusion The purpose of this lab was to answer the question regarding pill bug eating preferences being influenced by environmental factors. The data did not support the original hypothesis, and the experiment had too many sources of error to accurately test this hypothesis. This experiment can be used as a baseline to better adjust the experimental design and methods for future, similar experiments.

Literature Cited Aune P, Campbell J, Ferzli M, Niedzlek-Feaver M. 2020. Discovery and the scientific method in the biological sciences. In: Bio 181 General Biology Laboratory Manual. Plymouth, MI: Macmillan Learning Curriculum Solutions. p. 18–19. Tuck J, Hassall M. 2004. Foraging behavior of the Armadillidium vulgare in heterogeneous environments. [accessed 2019 Sep 13]; 144. https://brill.com/view/journals/beh/141/2/article-p233_6.xml...