Overview & Lesson Sequence

Focus on Standards & Assessment

Materials Needed, Preparation & Planning, Management Strategies

Background Info

Intro Activity
Why Study Populations?

Meet the Aphids

Research Project
Aphid Population Growth

Data Analysis I

Data Analysis II

Optional Activity
The Power of Exponential Growth

References

Glossary

Suppliers

Resource Sheets
-Plant Propogation
-Rearing Aphids
-Bottle Cages
-Clip Cages
-Eyelash Brush
-Petri Dish Habitat
-External Aphid Anatomy
-Internal Aphid Anatomy
-Aphid Observation Lab
-Sampling Methods
-Data Collection
-Observation Check Sheet
-Sample Rubric for Group Presentation

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Rearing Aphids

Aphids are small insects that feed on plants. Most species are host specific meaning that they will only feed on a particular plant species or family of plants. For rearing, select a species of aphid that is both easy to find and has a host plant that is readily available for purchase at a nursery, or can be grown from seed. Two methods are described below: raising Pea Aphids (the only species currently available for purchase), and raising wild-caught aphids.

Pea Aphids

Pea Aphids (Acyrthosiphon pisum) are available for purchase (see Suppliers) and work well for most classroom experiments. Before ordering the aphids, plant bush-variety pea plants or fava beans. Follow the Plant Propagation instructions. Time your plantings such that you have at least three true leaves before your aphids arrive (approximately two weeks). Once they arrive, unpack them carefully. The aphids are usually shipped on seedling plants that have been fastened with wire to the bottom of a styrofoam cup and covered with a clear plastic domed lid. Remove the wire and gently lift out the plant being careful not to disturb the aphids. Pea Aphids have an effective defensive behavior: they drop off of the plant when disturbed making them much harder to transport to your fresh pea plants. Carefully lay the stems of the shipped plant against the foliage of your pea plants in such a way that the aphids can crawl off the stem and onto your seedlings. Check the inside of the cup and plastic lid for any escapees and carefully transport them to one of the classroom plants with an eyelash brush. Care for the pea plants as suggested in the Plant Propagation sheet. If your classroom is exceptionally dry, you may want to build a makeshift plastic tent around the plants and growlights. Give the aphids at least two to three days to become established on the new pea plants before you begin handling them in classroom activities. These plants and aphid colonies are your stock colonies. Remember to plant additional pea plants approximately every two weeks because as the colonies grow, the plants will become stressed. Transfer the aphids to the fresh plants to keep the stock colonies healthy.

Cultivating "Wild" Aphids

Aphids are easy to collect in the wild and are most abundant in the spring and summer when their hostplants have a large amount of new growth. Often, if you find them near your classroom, you can observe them on the plant without disturbing them. However, you may want to rear them indoors for more in-depth experiments. As mentioned before, aphids are host specific and each species will need its corresponding host plant. Choose a species of hostplant that is easy to obtain from a nursery or can be grown from seed. The Milkweed Aphid (Aphis nerii) and the Cabbage Aphid (Brevicoryne brassicae) are good examples since seeds and plants are available at most nurseries. In addition, many aphid species feed on roses which are also readily available from most nurseries (however, be sure to wash the leaves and stems of store bought rose plants as they are often treated with pesticides).

Once your plants or seedlings have a few true leaves, you are ready to collect and transfer the wild aphids to the plants in your classroom. The best way to do this is to cut the whole infested stem from the outdoor plant that you found and then lay the stem against the foliage of your classroom plants in such a way that the aphids can crawl off the stem and onto your seedlings. As the original stem begins to wither and dry out, the aphids will automatically look for fresher, more luxuriant growth on the classroom plants. After the colony is established on the new plant and the population grows, the hostplant will show signs of stress. In order to keep your stock colony of aphids healthy, obtain fresh plants or plant new seeds approximately every two weeks and transfer some of the aphids to the new plants.