Category Archives: Science Projects

Under here you will have access to science project ideas that both teachers and students can partake.

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What stinks? A Fun Project for Finding Odor Preference in Milkweed Bugs

This post will give you the groundwork for designing a behavior experiment that will understand whether large milkweed bugs show preferences to different odors. This is a modified experiment of my award-winning project that jettisoned me to the Intel Internal Science and Engineering Fair for the second year in row in 2008.

 

Purpose

 The olfaction system is responsible for detecting various odors and smells and is one of the most common sensory systems among all animals.  Through specialized cells and chemical reactions, it enables you to detect various smells; from your freshly made cheeseburger to your rancid gym socks.

For insects, they use their antennae to detect chemical odors. The antenna sends electrical signals to the insect’s brain, which then determines how to respond to the odor. Insects’ olfaction system is especially important when it comes to detecting pheromones. Pheromones are small chemical messages that tell bugs where to search for food, the location of an insect mate, and the closeness of a predator.

Olfaction and pheromones are considerably important to large milkweed bugs as they have been shown to detect and follow pheromones during migration and colonization. In this experiment, you will determine whether these bugs show odor preference when it comes to decision making.

 Materials

  •  Large milkweed bugs (ideally 5-10 adults)
  • T-shaped connectors (2-3)
  • Clear plastic containers w/lid
  • Paper  towels
  • Plastic arena/aquarium
  • Sunflower seeds (200)
  • Plastic bags
  • Vinegar
  • Corn syrup
  • Olive oil
  • Lamp
  • Sponge
  • Measuring  cups
  • Brush
  • Cup

 

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For the large milkweed bugs, you can purchase them here.

I recommend shopping on amazon.com for the plastic arena/aquarium. You can purchase the T-shape connectors here.

Everything else can be purchased at your local store.

 

Procedure

 After the milkweed bugs have become adults (4-6 weeks), begin the experiment:

1)      Mix 40 sunflower seeds with ½ cup of corn syrup in a plastic container. Use a spoon to even distribution. Repeat this process two more times but with 1 set of the seeds bathed in olive oil and another set bathed in vinegar.  You should have a total of 120 sunflower seeds.

(Note: leave one set of 40 seeds untouched for they will be the control group in the experiment)

2)      Leave the seeds in their liquid solutions for a full 24 hours. After this, place each collection in their own separate bags and label them appropriately (i.e. olive oil seeds, vinegar seeds, corn syrup seeds, plain seeds).

3)      For the experiment, place a t-shaped connector on a paper towel. images_upload_2012_1cd_sku039775_4 At the opposite ends, place 2 normal sunflower seeds at the left end and 2 vinegar seeds at the other end.

4)      Retrieve an adult large milkweed bug from their housing unit via a brush and push them inside the t-shaped connector at the “stem” end. When secured, place a sponge at that end to insure that the bug must choose between the two opposite ends.

5)      Observe the bug as it interacts with the t-tube connector and record which seed side it choose. (Bonus: use a timer to record the total time the milkweed bug was in the connector before making a decision).

6)      Remove the bug, place it a separate container, and retrieve another adult milkweed bug for the next trial. Make sure that you throw away the sunflower seeds from the previous experiment and replace them with 2 more sets.

7)      When you have used all the adult bugs, return them to their housing unit.

8)      For the following days, repeat steps 2-7 but instead of vinegar seeds, use the corn syrup seeds, then olive oil seeds. Always remember that you are comparing regular sunflower seed with modified seeds.    Also, its recommend to use a different t-shaped connector.

 

Observation and Results

After finishing the experiment, did you notice whether the bugs showed preference for a modified seed over a normal sunflower seed? Did it seem as if the bugs spent different amounts of time for different modified seeds? Did they show preference for one side of the connector, regardless of seed type?

For the future trials, try using watermelon or squash seeds as milkweed bugs also like to eat them.  Also, try using other liquid-based food products.