The effect of over- feeding on the caterpillar species Vanessa cardui

<strong>The</strong> <strong>effect</strong> <strong>of</strong> <strong>over</strong><strong>feeding</strong>on thecaterpillar speciesVanessa carduiBy: Santiago LondoñoSantiago Londoño, Christopher Contreras, Alexander Rodríguez, Justin Carasa, Andrea Remiro, Nicole Cinquino, and Michelle Ortiz. 6/21/12 HHMI Research in Ecology 2012 Introduction <strong>The</strong> butterfly we tested on was the painted lady also called Vanessa cardui. <strong>The</strong> questionwe tested was how does <strong>over</strong>-<strong>feeding</strong> affect a caterpillars growth. Our hypothesis was that if you<strong>over</strong>-feed caterpillars, the caterpillars will grow faster than if you feed them the normal amount<strong>of</strong> food. <strong>The</strong> reason we tested this was in order to observe the difference between caterpillarseating the normal amount <strong>of</strong> food to caterpillars eating more than the normal amount. Anotherreason why we tested this was because we knew that most animals will grow larger than normalif you feed them large quantities <strong>of</strong> food.<strong>The</strong> reason we choose this type <strong>of</strong> butterfly was because the painted lady has a quick lifecycle. Something I found out during this experiment was that the painted lady flies around 1000miles in its lifetime. <strong>The</strong> Vanessa cardui has a wingspan <strong>of</strong> 2 inches and has black skin withspikes.Materials & Methods <strong>The</strong> materials we used are the following: a butterfly kit containing caterpillars, food, andcontainers, 2 wax pencils, 1 pair <strong>of</strong> scissors, 1 roll <strong>of</strong> tape, 2 bins, 1 small bolt <strong>of</strong> cheese cloth, 2light sources, 1 timer, 1 surge protector outlet. <strong>The</strong> first thing we did is count 22 containers andlids so that we could later put the caterpillars in. Next we measure the food for both groups. Weput 9.1 grams <strong>of</strong> food in each container <strong>of</strong> the control group and 13.6 grams <strong>of</strong> food in each <strong>of</strong>container <strong>of</strong> the treatment group (11 containers in each group). <strong>The</strong>n we put 1 caterpillar in eachcontainer. Next we put them in the bins separating the control from the treatment and labelingeach bin according. <strong>The</strong>n we check the temperature and the size and color <strong>of</strong> the caterpillars tosee if anything changed.ResultsDuring this experiment there were some strange things I noticed. One <strong>of</strong> the things Inoticed was that four caterpillars died in this whole experiment and all <strong>of</strong> them died frommysterious circumstances because when we looked at them we couldn’t see them at all as if therewas no caterpillar inside. For the statistical values <strong>of</strong> the control group I got a mean <strong>of</strong> 18.2 and avariance <strong>of</strong> 0.177778. For the treatment I got a mean <strong>of</strong> 18.875 and I variance <strong>of</strong> 0.982143. Forthe t test that I performed I got a P value <strong>of</strong> 0.105207 which means that I accept the null andreject the alternative.

Control Group Start Date Pupation Date Total Days Treatment Group Start Date Pupation Date Total Days C1 6/21/12 7/9/12 18 T1 6/21/12 7/9/12 18 C2 Dead T2 6/21/12 7/10/12 19 C3 6/21/12 7/9/12 18 T3 6/21/12 7/10/12 19 C4 6/21/12 7/9/12 18 T4 Dead C5 6/21/12 7/9/12 18 T5 6/21/12 7/12/12 21 C6 6/21/12 7/9/12 18 T6 Dead C7 6/21/12 7/10/12 19 T7 Dead C8 6/21/12 7/9/12 18 T8 6/21/12 7/10/12 19 C9 6/21/12 7/9/12 18 T9 6/21/12 7/9/12 18 C10 6/21/12 7/10/12 19 T10 6/21/12 7/10/12 19 C11 6/21/12 7/9/12 18 T11 6/21/12 7/9/12 18 Time Temp. Observations- Control Observations- Treatment Date 6/21/12 9:45 am 23°C No change No change 6/22/12 8:09 am 21°C No change No change 6/25/12 8:09 am 21°C <strong>The</strong>y have grown <strong>The</strong>y have grown 6/26/12 8:29 am 21°C <strong>The</strong>y look bigger, C-­‐7 is <strong>The</strong>y look bigger smaller than the rest 6/27/12 8:16 am 21°C C-­‐7 is dead No change 6/28/12 8:14 am 21°C All are big, forming web All are big except T-­‐4, forming web 6/29/12 8:21 am 21°C No change No change 7/2/12 8:21 am 21°C No change No change 7/3/12 8:09 am 21°C Have white stripes Have white stripes 7/5/12 8:18 am 21°C Bigger Bigger 7/6/12 8:13 am 21°C All are on the top All are on the top except T-­‐4, T-­‐6, T-­‐7 7/9/12 8:21 am, 21°C Chrysalis-­‐C-­‐1, C-­‐3, C-­‐4, Chrysalis-­‐ T-­‐9, T-­‐1, T-­‐11 C-­‐5, C-­‐6, C-­‐8, C-­‐9, C-­‐11 7/10/12 8:17 am 21°C Chrysalis-­‐C-­‐10, C-­‐2 Chrysalis-­‐ T-­‐10, T-­‐8, T-­‐3, T-­‐2 7/11/12 8:26 am 21°C No change No change 7/12/12 8:13 am 21°C One Chrysalis is starting to open No change

DiscussionIn the experiment we noticed that more caterpillars died in the treatment group than in thecontrol group. One reason why this might have happen was that since we put more food than theregular amount the caterpillars moving space was less than what it should have been. By doingthis the caterpillar might not have had enough space to turn into a chrysalis. According to thestatistics there was no significant difference but there was still a difference. <strong>The</strong> reason why therewas not a significant difference was that maybe we used a sample size to small or maybe toomany <strong>of</strong> them died.ConclusionSome <strong>of</strong> the questions that still remained after we finished the experiment were why did somecaterpillars not grow at all and the others did and why did some <strong>of</strong> them stop growing in themiddle <strong>of</strong> their growth.