St. Hubert School 2005
St. Hubert School
8201 Main St
Chanhassen, MN 55317
A Predators Banquet: Should We Dine On Swamp or Common Milkweed?
At a field site in Chaska, I randomly chose 5 common milkweed and 5 swamp milkweed plants and glued 3 monarch eggs and placed 3, 1st instar larvae on each plant. Each day I went back to the field, in the morning and before sunset, and counted the surviving eggs and larvae on each of my plants. I repeated this procedure twice, each time for about a week. My project was designed to find out whether or not monarch larvae or eggs survive better on common or swamp milkweed, and which type of milkweed invertebrates prefer, possibly to prey on the monarchs.
I found out that eggs survive better than larvae on both types of milkweed. Larvae usually lasted no more than one day on both types, although, because they were somewhat mobile, I might not have found them. In a survey of common and swamp milkweed plants in the field, I found that more invertebrates were found on common milkweed than swamp. The invertebrates found on common milkweed included ladybugs, milkweed bugs, milkweed beetles, ants and aphids.
Fresh, Refrigerated or Frozen: Which Milkweed Would You Prefer?
I conducted my experiment by placing fresh, frozen and refrigerated common milkweed into 9 plastic shoebox containers, 3 container for each treatment of milkweek. Then I added 3, first instar caterpillars to each container. I changed the milkweed each day and measure the growth and survival of the caterpillars every other day. I wanted to find out how the quality of milkweed affects the growth and development of monarch caterpillars.
At the end of my experiment, I found that the larvae eating fresh milkweed developed faster and were larger in growth than the other treatments. The larvae feeding on frozen milkweed had the highest mortality.
Some uncertainties had to do with possible errors in measurement. I would certainly recommend to teachers and young scientists that they feed their caterpillars fresh milkweed.
It's A Biodiverse Universe!
Michael C, Andy W
In this experiment, our class sent 5 groups into a mowed area and 5 groups into an ajacent field with nets to sweep for arthropods. We did this on 2 different 75 degree days at 1:00 PM. We did 4 swweps each, then bagged and froze the arthropods to group and count the next day. As a class, we sorted them by species in each bag and calculated the Simpson Index for each bag, then the class average. For the insect fair, we grouped all the mowed and all the field arthropods and calculated the Simpson for each area. We wanted to find out the difference in biodiversity between a field and mowed site, and if there was a difference in biodiversity between the morning class and our afternoon class.
When we calculated the Simpson Index for all arthropods in the field it was .158 and for the mowed area it was .128. The lower the number the higher the biodiversity, so the mowed area was slightly more diverse. Because they were so close, we accepted our null hypothesis which said there would not be a difference in the two areas. We also found that the 1:00 class had a greater biodiversity than the morning class.
There were some uncertainties. We tried to be random in where we started sweeping, but some groups might have swept more times or saw an insect and tried to catch it. We also might not have grouped the arthropods into all the separate groups. One thing we learned was that biodiversity of arthropods was about the same in the field and mowed area, and there were larger arthropods in the field that in the mowed site.
Monarch and Aphids and Ants, Oh My!
This summer, at Spring Peeper Meadow in Chaska, we went out once a week for 4 weeks and counted the number of invertebrates on 25 milkweed plants in 3 different locations. We looked for inverterates in an old field, established meadow and a hillside with small trees. At each location we measured the amount of rainfall each week, the temperature, soil moisture by each plant, how healthy the plant was, the skies and the number of invertebrates present. We wanted to find out if the kind of insects found on milkweed plants varied because of the different microenvironments.
Some of the invertebrates we encountered included ants, milkweed bugs, milkweed beetles, ladybugs and their larvae, many spiders species, flies (mostly syrchid flies), longhorn beetles, leafhoppers and aphids. Overall, ants were the most common species. Although we are still analyzing our data, it was obvious that some insects preferred some environments over the others.
As we were counting, we had field guides handy, but were uncertain as to whether we identified everything correctly. Sometimes things would fly or hop away before we could get a good look. This project was fun and we learned a lot about invertebrates from it. We would also like to know more about what happens between insects of difference species on milkweed plants.
Kristin S, Josh Z
To set up our experiment, we placed 3 millepedes in 3 containers filled with mulch, and set up a forth container the same way as our control. We then weighed 4 baby carrots, 4 slices of apple and 4 leaves of romaine lettuce and placed one of each in the 4 containers. Every day for six days, we weighed the food in all the containers and replaced it with fresh food. We also weighed the millepedes at the beginning and the end of the experiment. Our purpose was to see which food millepedes prefer, and how much they eat.
At the end of the experiment, we calculated the percent weight lost for each of the foods, (lettuce, carrots and apples) in the 4 containers. We averaged the percent weight lost for each of the three millepede containers and compared that with the weight loss in the control container without the millepede. The average percent lost for the containers with millepedes was 12% for lettuce, 10% for carrots and 6% for apples. In the control the percent lost was 13% for lettuce, 27% for carrots and 12% for apples. We noticed that most of the lettuce was eaten in each container, and there was gnawing on the carrots and the fleshy part of the apple.
Our big uncertainty was why the control had a greater percent loss than the experimental containers. We think that with several of us measuring each day, that errors occured. We did learn that millepedes eat at the surface during the night. We also learned that you need to repeat experiments many times to get accurate data and be careful when measuring.
Predation on the Prairie
For my experiment, I chose to perform a field study. I chose three common milkweed plants at a field site for each treatment set, each plant being the approximately the same size and health. Of these plants, I rubbed Vaseline on the stem of one to allow only flying insects to access it. I put a net aroung another to only let crawling insects in. To keep out all insects, as my control, I rubbed Vaseline on the stem and put a net around it. I did this to five sets, haviing a total of 15 milkweed plants. On each plant, I placed three eggs by cutting the leaf around the egg and gluing it to the underside of a leaf on the treatment plants using latex, the substance secreted by milkweed. After this was complete, I left the eggs for a full 24 hours and returned to count the number of eggs that survived on each plant in each treatment. I did this for 15 consecutive days. I wanted to find our how flying insects, crawling insects and no insects affect the survival rate of monarch eggs and larvae.
Analyzing my data after 15 days showed that, at first, more eggs and larvae exposed to crawling predators survived. Then the controlled set with no insects flourished and finished that way. The monarchs exposed to flying insects disappeared relatively quickly.
In doing this experiment, I learned that monarch caterpillars and larvae are most vulnerable to flying insect predators, and that they have a surprisinly low survival rate in their natural habitat. I also found that heavy rain is a very big factor in killiing the caterpillars and eggs.
Super Cool Caterpillars
I began my experiment by placinig five monarch larve randomly into a treatment. My treatments were made up of first instars, that were put in a dorm refrigerator in deli containers with common milkweed for 0,2,4,6,8,10,12 and 14 days. I used the same methods with second, third, forth and fifth instar caterpillars over the same number of days. I also placed three monarch pupae in in a refrigerated treatment for 0,2,4,6,10 and 14 days. Every day, for each instar in each treatment, I would measure the length and survival of the larvae. Once the larvae were removed from the refrigerator, after the appropriate number of days, I would raise them to adulthood, continuing to measure their growth, development and survival. I wanted to find out how refrigeration for two through fourteen days affects different stages of a monarch's (Danaus plexippus) growth and development. I had done a similar experiment with eggs last year). This question was important to me because it can help us to better understand the effects of the cool temperature on survival of monarch butterflies.
After 5 months of work and 5,995 data entries, I was able to come to a conclusion. I found that monarch larve and pupae could survive up to fourteen days in refrigeration, probably by slowing down their metabolism and digestive systems. However, once the larvae and pupae came out of the cool temperatures, they experienced high mortality after the 10 day treatments.
One uncertainty in my experiment had to do with the fact that my first and second instars were treated and raised in the summer, and survival was high, or in line with my control. The 3rd, 4th and 5th instar treatments were done later in the summer and fall, and mortality rates were high even in the treatments that were only in the refrigerator for very small amounts of time as well as the controls.
I learned that monarch larvae can be refrigerated up to 8 days without extreme mortality in early instar stages, but mortality seems to be higher in later stages after too much exposure to cool temperatures. To exlore my project further, I would like to retry the chysalis treatments with more days and a larger sample size.
The Effects of Lawn Fertilizer on the Mortality and Growth Rate of Different Categories of Aquatic Plants
In my experiment, I mixed lawn fertilizer with water using full concentration, 1/2 concentration, 1/4 concentration and only water. I poured two cups of each concentration into deli containers and placed measured numbers of 3 categories of aquatic plants (elodea, duckweed and algae) into each container. For each variety of plant and concentration of fertilizer there were 3 containers. The purpose of this experiment was to find out how different concentrations of lawn fertilizer affect the mortality and growth rate of of the different categories of aquatic plants. I found that for the elodea, the full concentration disintegrated the plants first, the 1/2 concentration next, then the 1/4 concentration and finally the control. The algae's exposure to the fertilizer caused the 1/4 concentration to bloom very fast, the 1/2 and control also bloomed, but not as much, and the full stayed much the same. In this experiment I did my best to control the variables that should be constant, but there could have been some minor errors in measuring the elodea because the growth was slow and I measured in millimeters. Although this experiment was not directly about insects, I learned that run-off of lawn fertilizers into ponds and lakes can affect the plant populations that I tested, and probably also affect the insect populations that use the plants for food and habitat. If I could continue with this experiment, I would test if the concentrations affect the plants more in hot or cold temperatures, and how changes in fertilizer affect insects that live with these plants.
Where Are You Hiding?
Our experiment, about the biodiversity of arthropods, was conducted over a 2 day period at 10:00 AM. Each day, 5 groups swept a field area and 5 groups swept a mowed grassy area. We swept 4 times for each bag that we filled. In order to count the arthropods we collected, we froze the bags for 24 hours, they separated them into species per bag. As a class, we averaged the Simspon Index for all of our bags in the mowed and all bags in the field area. Then, our group took all the arthropods from the field and sorted them, and all the arthropods from the mowed area and did the same. The purpose of this experiment was to find out it there were more arthropods in the mowed or field area, and if the time of day affected the amount of arthropods that were out.
We calculated the Simpson Index for all the arthropods in the mowed and found it to be .263, and for the field it was .254. The Simpson Index measures biodiversity or the chance that any two individuals chosen at random are the same. This means that the biodiversity of the field was slightly more that the mowed. We still accepted our null because it was so close. We also found there was more biodiversity in the afternoon than the morning, but not by much.
Some uncertainties were that the total area for the mowed was much small and narrower than the field. Also when we did our sweeps the first day, not everyone kept the number the same. Some new things we learned were that to conduct a good experiment you have to be very organized, and you have to collect a lot of samples.