David Hill, Matt Redmon, Tiphanie Copeland

Jordan Park School of Extended Learning
Minneapolis, MN

  Introduction  |  Methods   |  Results  |  Discussion  |  Acknowledgements   | Biographies |  Research Projects

Introduction

Is it possible to make monarchs larger than usual by providing them with extra nutrients?  We decided to start this research to find out if there is a way to create monster butterflies.  While measuring butterflies during field research, we observed that some monarchs were larger than others.  Those observations raised some questions.  How do nutrients affect monarch growth?  How do the effects of nutrients compare to the effect of genetics?  We thought it would be fun to see if we could alter monarch growth by adding nutrients to their basic milkweed diet.

Hypotheses

H_o:   Adding nutrients will have no effect on monarch growth and development.
H_a1:  Adding nutrients will positively affect monarch growth and development.
H_a2:  Adding nutrients will negatively affect monarch growth and development.

Methods

We tested our hypotheses by rearing monarch larvae under three treatments.  One group was the control and received regular milkweed (Asclepias syriaca).  The second group received regular milkweed dusted with bee pollen.   The third group received regular milkweed misted with a 20% sugar solution.   We kept all the larvae at school during the week and took them home during the weekends.

We received 60 monarch eggs from the University of Minnesota Monarchs in the Classroom program.  Twenty eggs were introduced into each of three containers containing the three milkweed treatments (control/untreated, sprayed with 20% sugar solution, and dusted with bee pollen).  We applied the treatments to all of the milkweed leaves in the containers.

We began weighing the larvae three days after the eggs hatched.   Each weekday we weighed and measured the length of each larva in each group.   We kept track of larval survival.  We cleaned the cages each day and provided the larvae with fresh, treated milkweed.  We continued feeding the larvae over weekends, but no data were collected over the weekends.  Our measurements ended after the larvae pupated.

Results

Mortality
Forty-four out of 60 larvae died before they reached the adult stage.  In the control and sugar groups, 7 larvae lived and 13 died.  In the pollen group, 2 lived and 18 died.  Using a Chi-Square test, we found that there was no difference in monarch survival among the three groups (X² = 4.26, df = 2, p = 0.1188). 

Table 1.  Observed and expected numbers of larvae surviving and dying in three treatments.

Size
We compared the mass of the larvae in the three groups using T tests.  We compared the mass and length of the larvae on the last day that we measured them.  We could not include the bee pollen treatment larvae in the comparison because only one larva survived until this time.  We compared the mass and length of the control group larvae and the sugar larvae and found a significant different between the two groups.   The mean mass was 1.035 for the sugar group and 1.151 grams for the control group (Figure 1).  The mean length was 37.5 mm for the sugar group and 45.25 mm for the control group (Figure 2).  There was not a significant difference in mass between the two groups (t = 3.03, p = 0.203).  We failed to reject our null hypothesis of no difference in mass.  However, monarchs in the control group were significantly longer than monarchs in the sugar group (t = 2.45, p = 0.035).  We rejected our null hypothesis of no difference in length. 

Figure 1.  Average mass of larvae over time for three treatments.

Figure 2.  Average length of larvae over time for three treatments.

Discussion

We ran into a few challenges while conducting our experiment.  In the process of learning about monarchs and their life cycle, we came to understand just how fragile these creatures are.  Initially we had wanted to see if the larvae could grow on a diet of butter applied to the bottom surface of milkweed leaves.  We discovered that many of the larvae for this experiment died in the oily film.  Those larvae that did survive were severely emaciated.  Because of the apparent cruel nature of this experiment, we decided to just test the sugar solution and bee pollen.  Also, we were surprised to learn that monarch larvae will cannibalize other eggs.  Some of the eggs never hatched because the larvae that hatched first ate them.  We found that it was difficult to supply fresh milkweed each day.  Weighing and measuring the larvae was also very tedious work.  Taking the larvae home did not always work, due to parental reasons--especially when larvae pupated on the lamp shade!

We also had some additional observations.  Most notably, we observed that the color of the larvae was different among the three groups.  Those in the control group had what we considered a normal color.  However, the larvae in the sugar solution group had a dingy color and the larvae in the bee pollen group appeared to be even brighter than the control larvae. 

Acknowledgements

We wish to express our thanks to Karen Oberhauser and the staff of Monarchs in the Classroom for making this opportunity available.  We wish to thank our teacher Mr. Hill for walking us through the process.  Special thanks to Dr. Gupton, Principal of Jordan Park School of Extended Learning.  Thanks also to our understanding and patient parents.  We thank the students who supported and aided us:  Chase Foote, Erin Laxton, Dwayne Fisher and Mai Der Vang.  Finally, we thank the National Science Foundation, the Science Museum of Minnesota and the Bambergers for the use of their wonderful ranch.

Biographies

David W. Hill is a seventh and eighth grade science teacher at Jordan Park School of Extended Learning.  He is a scientist in the field of limnology and has been in the field of education for 27 years.  He is married and has three grown children and three grandchildren.  He enjoys his research, cooking, and fishing.

Matt Redmon is an eight grader at Jordan Park SOEL.  He enjoys science projects like this one.  He also enjoys meeting new people.  He says that if he ever had a chance to do another project like this one, he would!

Tiphanie A. M. Copeland goes to Jordan Park SOEL and will be going to Washburn High.  She likes to listen to the Backstreet Boys and loves to do math.  She hopes to be working with the government soon.  She also hopes to do another program like this one in the future.