The Effect of Environmental Preference on the Location Chosen by the Darkling Beetles

Title: The Effect of Environmental Preference On The Location Chosen By The Darkling Beetles

Introduction: The purpose of this lab involving Darkling Beetles is to experiment their environmental preference when given two choice; empty half of choice chamber or vegetation side. The variable that we will be manipulating is the environmental area (independent variable). The variable that is going to respond to the independent variable is the Beetles choice (dependent variable). By using these two variables we will be measuring with trial and error whether the Beetles would prefer vegetation or nothing. In order for the experiment to be substantial and accurate we need to have a control variable as well. Our control variable is an empty choice chamber trial and error, where nothing is put into the choice chamber so we can rule out the thought of one Beetle having a certain prefereance of North or South before adding in our other variables. Our main subject of this experiment, "Darkling Beetles (also known as darkening beetles or grub) are a family of beetles found worldwide, estimated at more than 20,000 species. Darkling beetles eat both fresh and decaying vegetation" (ask.com). From this researched information before even beginning the experiment we can create a hypothesis: If the environment has vegetation, then the Darkling Beetles will crawl to its natural habitat/food source.

Materials and Methods: After reading over the Experimental Design Lab my group and I had to decide what variables we wanted to use throughout the experiment. After observing the Darkling Beetles for a few moments, all 50 + Beetles crawling all over the big beakers we wanted to experiment with the Beetles' choice of vegetation vs. no vegetation. Not only did we have to test with trial and error the Beetles' choice of vegetation vs. none, but also test the Beetles' choice between nothing and nothing. In order to get accurate consistant data it is important to always have a control group in experiments. To begin the lab we were given one choice chamber, which is basically two petri dishes sitting side by side with no barrier in the middle blocking access. The choice chamber had a cover to it to ensure that the Beetles wouldn't try to crawl outside of the experimental walls. After we lied out the choice chamber on our lab station we went to the middle table to get five Darkling Beetles, using a paintbrush to make getting the Beetle easier, and put each Beetle in a cup and numbered each cup for organizational and experimental purposes. Because the Beetles are very quick and delicate, we had to ensure that the Beetle was safe, by being very gentle and cautious of each one. As a group we decided to first experiment with the Control Group; each Beetle had fifteen seconds to choose which direction (either North or South) they would take. I used my iPhone as a timer to ensure that each Beetle had the same amount of time. The first trial with Beetle 1 went as follows: Morgan took the cup labeled Beetle 1 and slid the Beetle out of the cup, after the Beetle was in the empty choice chamber Morgan used the brush side of the paint brush to line of the Beetle equally between both sides of the chamber. After the Beetle was in perfect alignment we put the lid on the choice chamber I started my timer and gave the Beetle fifteen seconds to choose a side. When the time was up we took the Beetle out of the choice chamber, recorded in our data table which side it chose and repeated twice more with the same Beetle. With each Beetle we repeated this step three times (three trials per Beetle); we had five Beetles tested in the Control Group three times giving us a total of fifteen trials. After collecting this data and transferring it into our data table we moved on to test the Beetles' choice of vegetation. The vegetation we used was from HPHS, using mini leaves that came from a tree. As a group we removed each leaf from the stem and placed around 30-40 leaves in the North side of the choice chamber. Because in this step we were testing the dependent variable (Beetles' choice) we had to leave the other side of the choice chamber empty. While manipulating the environmental area we used the same time, fifteen seconds, for each Beetle to decide between vegetation and no vegetation. Beginning with a new set of data for the Experimental Group Morgan took the cup labeled, Beetle 1 and slid the Beetle into the center, using the same positioning as before while testing the Control Group. After Morgan told me the Beetle was ready we put the lid on the choice chamber and I started my timer and allowed the Beetle to decide for fifteen seconds between vegetation (which is its' source of food and home) and nothing. After the fifteen seconds were up we took the Beetle out of the choice chamber, recorded in our data table which side it chose and repeated twice more with the same Beetle. Just like in the Control Group we tested each Beetle three times. After testing both the Experimental and Control group we brought back the Beetles to the middle table and placed them carefully into the beaker, and bringing the paint brush, choice chamber and lid as well.

Results: This data table shows the effect of environmental preference on the location chosen by the Beetles,