Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
In order to reject the possibility that the results
obtained were influenced solely by chance, a Fisher’s
exact chi-squared test was performed. By obtaining a
p-value significantly less than 0.05, the null hypothesis
stating that chance could be the only factor affecting
the data can be rejected (Figure 2). The p-value
indicates that there must exist other factors, besides
chance, that influenced the results obtained. Thus, our
hypothesis that a higher temperature would increase the
rate of metamorphosis in comparison to a lower
temperature is supported since the data values obtained
do not mimic those received by chance.
Given an ample food supply, living
environments and similar light sources, the only
variable determined was the temperature of incubation.
Thus, the circadian rhythm of V. cardui could only be
affected through temperature control. According to
Pollard (1988), weather was hypothesized as a factor
related to butterfly populations. The data of this
experiment clearly depicts that the temperature of
incubation, which would mimic the representative
weather conditions, did indeed contribute to the rates of
metamorphosis from larval to cocoon in V. cardui.
These rates would thus affect the butterfly populations
of the specified sample groups as butterflies appeared
more rapidly in the warmer temperatures. The
conditions of which the larval stages are being held do
indeed affect the populations of the adult stage. The
results of this experiment could indicate that PTTH
became more readily available at 27.7°C or that the
larval stages began cocoon at a higher temperature as a
cause of expending less energy on metabolism. The
data merely reflects temperature’s effect on V. cardui’s
metamorphic rate.
Throughout the world, Vanessa cardui is the
most distributed butterfly (Marrero and Nunez 2005).
This experiment may suggest that V. cardui’s
population is directly related to the environment in
question. In short, the warmer climates must house the
larval stages, while the milder temperatures would
provide a niche for the adult stages. V. cardui is known
to migrate, which would thus advocate the migration to
warmer climates; warmer climates would favor the
increase of the rate of metamorphosis in V. cardui.
Thus, the hypothesis would suggest that higher
populations of the Painted Lady butterflies would exist
in warmer climates.
Data values obtained were from V. cardui of
the sample groups, which were originally held at an
unspecified temperature during their birth at the
Mulberry butterfly farm. The data suggests that a
higher incubation temperature would induce a faster
rate of metamorphosis, regardless of the generation.
Had this experiment been performed again, the data of
the offspring from the original sample group should be
examined and taken into account. The results of this
experiment could further validate that the rate of
metamorphosis based upon temperature of incubation.
Acknowledgements
The investigators acknowledge Mulberry Farms for
supplying the larvae, artificial diet and rearing cups and
Professor Steve Teh for assisting in the set-up and data
collection in the Saddleback Student Research
Laboratory.
Literature Cited
Debinski, D. and Kelly, L. (1999). Effects of larval
food-limitation on Vanessa cardui Linnaeus
(Lepidoptera: Nymphalidae). The American Midland
Naturalist. 141(2): 315-320.
Gotthard, K. (2004). Growth Strategies and Optimal
Body Size in Temperate Pararginii Butterflies.
Integrative and Comparative Biology. 44(6). 471-479.
Lampel, J., Briscoe, A., Wasserthal, L. (2005).
Expression of UV-,blue-, long-wavelength-sensitive
opsins and melatonin in extraretinal photoreceptors of
the optic lobes of hawkmoths. Cell Tissue Res. 321:
443-458.
Marrero, L. Nunez, R. (2005). Vanessa cardui Poey
(Lepidoptera: Nymphalidae), a new report for soybean
in Cuba. Rev. Protección Veg. 20(1): 60-61.
Pollard, E. (1988). Temperature, rainfall and butterfly
numbers. Journal of Applied Ecology. 25: 819-828.
Scott, J.A. (1992). Direction of spring migration of
Vanessa cardui (Nymphalidae) in Colorado. Journal of
Research on the Lepidoptera. 31 (2): 16-23.
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Saddleback Journal of Biology
Spring 2010