Butterfly Color Preferences
Our class question was "How does the color of the flower affect monarch butterfly eating habits?" Our hypothesis was that monarchs would have a preference for purple, yellow or pink flowers. Our null hypothesis was that they would have no color preference. We decided to also compare males and females. We tested 15 males and 15 females using nectar on sponges. They had been "starved" for 24 hours. We timed both their landing preferences (sitting on a sponge but not eating) and their nectaring preferences for a 30 minute period. Both males and females preferred purple and pink over the color yellow. However, I feel that these results are not conclusive. We can conclude that, at least in our samples, males spent much more time nectaring than the females.
Butterfly Wing Patterns
As a class, we studied monarchs and learned that males have a black spot on their rear wings and females do not. We also observed that females wing veins were thicker than males. From these observations we came up with the question How does gender affect monarch wing patterns. We were interested to see if there were any other differences. Our hypotheses were that males and females would have different sized wing cells and that they would have differing numbers of white spots on their wings. Our null hypothesis is that the wing patterns (besides the things already mentioned) would be the same in males and females. For our experiment we looked at 30 male and 30 female wing sets. As a class we randomly chose one cell per wing and measured across the largest point. We then counted all the spots on one hind wing (chosen by coin toss). Our results show that the average wing cell is larger in female monarchs than in males. Females also have more white spots on their hind wings. I think this makes sense because in many species of animals I have researched, the female is the larger of the two genders.
Our class problem was How does the condition of the milkweed leaf affect the eating habits of monarch larvae? Hypothesis #1: milkweed condition would affect the eating habits of 1st- 3rd instars, but not 4th or 5th instars. Hypothesis #2: milkweed condition would affect monarch larva eating habits regardless of the instar stage. Hypothesis #3: poor condition milkweed would result in monarchs eating less. Null Hypothesis: milkweed condition would have no affect on monarch larvae eating habits. We started with 2nd instars (we didnt get to check 1st instars because they had already molted!). We traced eight leaves of good condition and eight of poor condition. Good condition leaves were green with no dry spots and poor condition leaves were yellowed. We put a larva in a bin with each leaf and left them for six hours. We then traced the amount eaten on each drawing so we could figure out the area that was eaten from each leaf. We repeated this procedure for 3rd, 4th and 5th instars. We found that larvae in every stage prefer milkweed in good condition, but that as they get larger they are less particular are more willing to eat the poor condition plants.
Sarah G, Callie S
Our class question was How does the size of the larva affect the size of a chrysalis? Our hypothesis was that larger larvae would form a larger chrysalis. Our null hypothesis is the size of the larva has no effect on the size of the chrysalis. To test our hypotheses we measured the length and mass of 5th instar larva each day they formed a chrysalis. We then found the length and mass of each chrysalis. We found that the mass of the larva in most cases affects the size of the chrysalis more than the length of the larva. However, our measurements for length may not have been as accurate. In conclusion, the mass of the chrysalis is affected by the mass of the larva.
Some Like It Hot
Our class question was How does temperature affect the growth rate of monarch larva? Hypothesis #1: As the temperature of the environment goes up, the larva will either increase in mass or not change compared with the room temperature growth rate. Hypothesis #2: As the temperature of the environment goes down, the larva will decrease in mass compared to the room temperature growth rate. We prepared six bins, each with five 2nd instar larvae. Each bin was set in a location with a different temperature ranging from 10o- 35o C. Each larva was measured about every two days. Larvae in the coldest temperature did not survive. The larvae in the hottest temperatures grew at a slower rate than those in the middle temperatures of 15o-25o C. We did have some uncontrolled variables that interfered with our results. However, we can conclude that most larvae grow better in normal temperatures.