The Effect of Caffeine on Caterpillar Development

<strong>The</strong> <strong>Effect</strong> <strong>of</strong> <strong>Caffeine</strong> on Caterpillar Development
By the Olympic Frenzy Fishermen
Abstract
<strong>The</strong> purpose <strong>of</strong> this scientific project was to find out if the amount <strong>of</strong> caffeine that our
group emitted into the caterpillars diet would affect survival <strong>of</strong> the caterpillars to
emergence. We gave one group <strong>of</strong> caterpillars a dose <strong>of</strong> caffeine in their food, and the
other group got a placebo (distilled water). <strong>The</strong>re was no difference in the survival rate
between the control and the treatment groups.
Introduction
We decided to perform an experiment on lady painted caterpillars to test if caffeine
would affect the survival <strong>of</strong> caterpillars from the start <strong>of</strong> the experiment to pupation.
From previous given information, we know that caffeine can make people very hyperactive
and high consumption <strong>of</strong> caffeine affects one's health level. Our null hypothesis
was that there was going to be no difference between the survival to pupation <strong>of</strong> the
caterpillars who are exposed to caffeine and those caterpillars that are not. Our
alternative hypothesis was that there was going to be a difference in the survival to
pupation between the caterpillars who are exposed to caffeine and those who are not. We
then predicted that more caterpillars will die when caffeine is added to their regular diet.
Methods
We separated 15 caterpillars into one group and 15 into another group. We got a 200
mg caffeine tablet and crushed it with 1.5 milliliter <strong>of</strong> water for our treatment group.
<strong>The</strong>n we measured 8 grams <strong>of</strong> caterpillar food to be put into every cup (for both the
control and treatment {caffeine} group). We then took the cups and added 0.1 milliliter
<strong>of</strong> caffeine solution to each treatment cup and 0.1 milliliter <strong>of</strong> water in every control cup,
and mixed it with the food. Finally we put the caterpillars into each <strong>of</strong> their separate cups
and began our watchful experiment. We used a Chi-square test to see if there was a
significant difference in survival between treatment and control groups.
Results
We recorded how many <strong>of</strong> each group survived or died on each observation day
(Table 1). In the control group, 14 caterpillars survived (93%) and 1 died (7%). In the
treatment group, 11 (79%)survived and 4 (21%) died. Overall, 83% survived and 17%
died. (Table 2)
<strong>The</strong> Chi-Square calculated value <strong>of</strong> 2.129 is less than the tabled value <strong>of</strong> 3.84 at 1 df
and p=.95 value. <strong>The</strong>refore there is no difference in the survival rate between the control
and the treatment groups. We cannot reject the null hypothesis.
Discussion
We did not see a difference in survival from start <strong>of</strong> the experiment to pupation
between our treatment and control groups. We learned from Dr. Krempels that
caterpillars can detoxify many poisons found in plants (such as caffeine), and we think
that maybe the caterpillars were not affected by the caffeine because they are not
poisoned by it the way humans are. This tells us that chemicals can affect different

species in different ways. This was a surprise because we thought that caffeine would be
bad for the baby caterpillars.
If we did this experiment again, we would try to see if there was a difference in the
rate <strong>of</strong> pupation or the time from pupation to emergence in caterpillars given caffeine or
not given caffeine, because even if survival is not affected by caffeine, other things in the
caterpillar life cycle might be.
Tables
Table 1: Caterpillars that lived or died in the treatment group (caffeine) and in the
control group (no caffeine). <strong>The</strong>re was no significant difference between the groups.
Treatment
Control
1 - LIVED 16 - LIVED
2 - LIVED 17 - LIVED
3 - LIVED 18 - LIVED
4 - LIVED 19 - LIVED
5 - LIVED 20 - LIVED
6 - DIED 21 - LIVED
7 - LIVED 22 - LIVED
8 - LIVED 23 - LIVED
9 - DIED 24 - LIVED
10 - LIVED 25 - LIVED
11 - LIVED 26 - LIVED
12 - DIED 27 - LIVED
13 - DIED 28 - DIED
14 - LIVED 29 - LIVED
15 - LIVED 30 - LIVED
TOTAL DEAD = 4 TOTAL DEAD = 1
TOTAL SURVIVED = 11 TOTAL SURVIVED = 13
Table: 2. Survival rates <strong>of</strong> the caterpillars. Total survival rate = 0.83. Predicted to
survive (.83) (15) = 12.45. Total Death rate= 0.17. Predicted to die (.17) (15) = 2.55
Chi-Square Value at 1 df equals 2.129
Group Control Treatment
Survived 14 11
Died 1 4
Total started /w 15 15
Group control Treatment
# survived observed 14 11
# survived predicted 12.45 12.45
# died observed 1 4
# died predicted 2.55 2.55