Relationships between migrating monarchs’ flower color preference, monarch wing loading, and the monarchs’ preference for native or non-native flowers in North Texas
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Crystal Buchko (R), Tiffany Harrison (C) and Joylynn S. Woodruff (L) Decatur
High School Abstract | Introduction | Methods | Results | Discussion | Acknowledgements | Literature Cited | Authors | Research Projects We investigated the following questions: Is there a difference in flower preference, is there a correlation between flower color preference and wing loading, and do migrating monarchs prefer native or non-native flower types? The tests for flower color preference indicated that migrating monarchs do indeed have a flower color preference, with that preference being white. The tests for flower color preference and wing loading suggested that relatively heavy and light butterflies do not differ in flower color preferences. Finally, the tests for preference of native or non-native flower types did not show that migrating monarchs have a preference. These results offered us insight into the preferences monarchs have during their migration from the northern United States and Canada, to their over-wintering sites in Mexico. These tests should be repeated to verify the results, and perhaps another study should be included considering the sex of the monarchs. IntroductionNutrition is a key factor in the survival of migrating monarch butterflies. As they migrate southward, the vegetation changes drastically with the changing climate. Therefore, migrating monarchs probably do not become acclimated to flowers native to a specific area, but they can develop a color preference (Kondo, 1970). Further research indicates that butterflies are attracted to brightly colored objects, and that males are prone to nectar on white flowers whereas females prefer colored ones (Gynup, 2000). Our objective is to determine if there is a correlation among the migrating monarchs’ flower color preference and their wing loading (the mass of the butterfly in relation to its wing length), and also whether monarchs prefer native or non-native flowers in North Texas. In a preliminary experiment, we observed that some migrating monarchs nectared from many flower colors while others appeared to nectar primarily on one color of flower (team observation). We used wing loading in relation to flower color preference because we thought that skinny butterflies might not be choosy because they were hungrier, whereas fat butterflies could afford to be choosy about which flowers they nectar from. To determine our outcome, we observed the feeding habits of adult monarchs on diversely colored native and non-native North Texas flowers while measuring the wing loading of the individuals. Our observation was conducted in a laboratory setting using monarch butterflies raised from eggs with no prior exposure to flowers. The questions we investigated and the hypotheses for each follow:
We started our project by identifying native flowers in bloom. From the schoolyard we obtained four different flowers with a similar structure: a purple Slender Vervain (Funnelform epigynous), a white Plains Yarrow (Achillea lanulosa), a yellow Partridge Pea (Chamaecrista fusciculata), and a yellow Berlandier’s Golden Aster (Chrysopsis berlandieri). We then located four non-native flower types (with as similar structure and color to the native flower types as possible) which included a purple New England Aster (Aster chilensis), white Baby’s Breath (Gypsophila paniculata), a yellow sunflower (Helianthus annuus), and a yellow chrysanthemum (Anthemideae parthenium). Equal numbers of each color of flower, for a total of about 32, were placed in four vases in the observation hood of our classroom. The vases were alternated with native and non-native flower types in one row across the middle of the hood (Pictures 1 and 2). The experimental butterflies were donated by Mississippi Heights Middle School in Sauk Rapids, Minnesota and sent to Texas as eggs. The butterflies were allowed to mature, and as adults were allowed to nectar on sponges with 10% honey water for five minutes per day until 13 adults had emerged. When the adults emerged, butterflies were marked and wing loading was determined by dividing the butterfly mass by wing length. Six butterflies were determined to be of lower wing loading .056-.092gr/cm (Babies) and seven butterflies were determined to be of higher wing loading >.092-.130gr/cm (Bubbas). We placed all 13 monarch butterflies into the hood at one time, and observed the butterflies nectaring. (We counted a butterfly that stuck its proboscis out and into a flower as nectaring.) For fifteen minutes once each day for three consecutive days, each butterfly was monitored for the number of nectaring visits on specific flowers. After 15 minutes of observing, the butterflies were allowed to nectar on fresh honey water sponges for five minutes. All butterflies successfully nectared from the sponges. We performed Chi Square tests to determine if the monarchs had a color preference, if there was a relationship between color preference and wing loading, and if there was a preference for native or non-native flowers.
During the three days of data collection, all 13 monarch butterflies nectared on white, yellow, and purple flowers. We rejected our null hypothesis, which stated that migrating monarchs have no flower color preference. (X2=9.1, df=2, p=< .01) The monarchs nectared 13 times on white flowers, 4 on yellow, and 3 on purple, totaling 20 visits. Migrating monarchs preferred white flower colors, with respect to the flower colors tested. The following graph shows the flower color preferences exhibited. (Figure 1.)
When considering the wing loading and flower color preference, we failed to reject our null hypothesis which stated that there is no correlation between the flower color preference and the wing loading of migrating monarchs. (X2 = .4, df=2, p>0.1) The higher wing loading monarchs ("Bubbas") nectared 7 times on white flowers, 2 on yellow, and 1 on purple, totaling 10 visits. The lower wing loading monarchs ("Babies") nectared 6 times on white flowers, 2 on yellow, and 2 on purple, totaling 10 visits. The following graph shows wing loading and flower color preferences exhibited. (Figure 2.)
In our last test, considering preference for native and non-native flowers we failed to reject our null hypothesis, which stated that migrating monarchs have no preference for native or non-native flower types. (X2=.8, df= 1, p>0.1) 12 monarchs nectared on native flowers and 8 on non-native flowers. The following graph shows monarch preferences to native or non-native flowers. (Figure 3.)
DiscussionThe first question we investigated resulted in rejecting the hypothesis that migrating monarchs have no flower color preference. White appears to be preferred. In the second question, wing loading and flower color preference, we failed to reject the null hypothesis, that there is no correlation between the flower color preference and wing loading. In testing whether migrating monarchs prefer native or non-native flower types, we failed to reject our null hypothesis, monarchs have no preference for native or non-native flower types. Similar studies indicate that there is a correlation between the sex of the monarch and their feeding habits, stating that males prefer white flower types while females prefer colored flower types (Gynup, 2000). Other results have shown that monarchs are attracted to brightly colored objects (Kondo, 1970). Our results showed that there was a preference to white instead of brightly colored flowers, looking at males and females combined. These results may have been affected by the fact that during the time this experiment was conducted white flowers were the dominant color in the field. Wing loading did not appear to be a factor in choice of color or native/non-native flowers but this should be investigated further using wild monarchs captured during an actual migration. Our results could have been affected by the fact that our project was conducted in the lab. The original research plan was to conduct a field study, but due to inclement weather and the fragile health of our monarchs, we transferred our studies to the classroom. However had we conducted a field study, our results might have been affected by environmental factors such as the wind, other insects, and the larger amount of space. One factor that was an unexpected variable was, once the monarchs began the honey water supplemental feedings the wing loading difference was probably insignificant. Another significant factor was the low number of monarchs that were available for the experiments; more data would be preferred to verify these results. Further studies could be conducted to determine if feeding habits are similar along the entire migratory route during actual migration, as well as a study comparing males and females. AcknowledgmentsWe would like to thank the National Science Foundation (ESI-9731429) and Decatur High School for financial support, our University of Minnesota instructors for working with us, and Mrs. Woodruff’s classes for help with feeding, weighing, and babysitting the monarchs and larvae. We also owe special thanks to Mississippi Heights Middle School in Sauk Rapids, Minnesota for the butterfly eggs, to Decatur and surrounding communities for contributing supplies, field sites, and financial support, and to our scientist mentors, Bethann Lavoie and Michelle Solensky. Literature Cited Kondo, Herbert. "Monarch Butterflies." Grolier’s Amazing World of Animals, 1972, 16,8. Guynup, Sharon. "Homeless Butterflies" Science News 3 November, 2000, p. 4. Monarch Lab website, http://www.monarchlab.umn.edu Swan, Lester and Papp, Charles. The Common Insects of North America. Canada, 1972, 218. Crystal Buchko is currently a junior at Decatur High School in Decatur, Texas. She is active in the high school community service organization, "The EarthSavers" and participates in other activities with her church youth group. She is a native of Minnesota and hopes to return to her home state to pursue a degree from the University of Minnesota. Tiffany Harrison is currently a junior at Decatur High School in Decatur, Texas. She is a member of the state qualifying cross-country team and the DHS track team. She participates in charity races throughout the state of Texas. After graduation from DHS, Tiffany plans to attend Stephen F. Austin University, pursuing a degree in psychology. Joylynn Woodruff has been teaching biology (all levels) 23 years in Texas public schools. She is the EarthSaver sponsor, Science Fair Coordinator, District Curriculum Team member, and mentor teacher to at-risk students. Joylynn enjoys working with students because they teach her new things as she teaches them, in her classroom "learning is a shared experience". Back to top | Vital Statistics | Student/Teacher Research | Research Topics | Site Overview |
