Abstract

Objective

The objective of this project is to determine the most effective treatment for whitefly infestations on garden plants (e.g., Hibiscus, tomato, pointsettia, and others). Potential treatments for comparison include: soaps, oils, biopesticides, insect growth regulators, or insectides. The different treatments are compared to each other and to a treatment of water alone.

Introduction

Whiteflies (see pictures in Figure 1, below) are a group of related insect pests whose larvae, like aphids, get nutrients by sucking juices from plant leaves and stems. In addition to the primary damage they cause by depriving plants of vital nutrients, whiteflies can cause harm in other ways. They secrete relatively large quantities of honeydew, which encourages the growth of harmful fungus, and may also attract other harmful insects. Whiteflies can also transmit viruses which cause disease in plants.

Figure 1. Four different species of whitefly (clockwise from top left): bandedwinged whitefly, greenhouse whitefly, sweet potato whitefly, and silverleaf whitefly (Fasulo et al., 1995).

Whiteflies have predators, including some parasitic wasp species, and ladybugs. Using broad-spectrum insecticide treatments to try to control whiteflies can lead to killing off these predators, and to the development of insecticide resistance in the whiteflies that survive.

Biorational pesticides are more focused methods of chemical control that aim to manage the pest species with the minimum amount of disturbance to non-target species. Biorational pesticides for whitefly control include insecticidal soaps and oils, and insect growth regulators, which kill by delaying larval development.

In this project, you'll compare the effectiveness of different treatments for controlling whiteflies.

Terms, Concepts, and Questions to Start Background Research

To do this project, you should do research that enables you to understand the following terms and concepts:

• whiteflies:
  • greenhouse whitefly,
  • bandedwinged whitefly,
  • silverleaf whitefly,
  • sweet potato whitefly,
  • how to identify them, and
  • most effective pest management strategies for each;
• integrated pest management (IPM),
• biorational insecticides:
  • insecticidal soaps and oils,
  • insect growth regulators.

Questions

• What are some disadvantages to using insecticide treatments for insect pests in the garden?

Bibliography

• Fasulo, T.R., et al., 1995. "USDA Whitefly Knowledgebase," United States Department of Agriculture and Department of Entomology and Nematology, University of Florida [accessed October 16, 2006] http://whiteflies.ifas.ufl.edu/wfly0002.htm.
• Wikipedia contributors, 2006. "Whitefly," Wikipedia, The Free Encyclopedia [accessed October 16, 2006] http://en.wikipedia.org/w/index.php?title=Whitefly&oldid=80716701.
• Greer, L., 2000. "Greenhouse IPM: Sustainable Whitefly Control," ATTRA Pest Management Technical Note [accessed October 16, 2006] http://attra.ncat.org/attra-pub/PDF/ghwhitefly.pdf.
• Cranshaw, W.S. and B. Baxendale, 1999. "Insect Control: Horicultural Oils," Colorado State University Cooperative Extension [accessed November 3, 2006] http://www.ext.colostate.edu/PUBS/INSECT/05569.html.

Materials and Equipment

To do this experiment you will need the following materials and equipment:

• plant(s) with whitefly infestation:
  • many plants are susceptible, e.g., Hibiscus, tomato, pointsettia, and others;
  • if the plant is large enough (e.g., hibiscus), you can try different treatments on different branches.
• you will need to research and select 3–5 different control methods to test:
  • biopesticides, e.g.:
    • Naturalis-O or BotaniGard (both based on the fungus Beauveria bassiana),
    • PFR-97 (based on the fungus Paecilomyces fumosoroseus);
  • least-toxic (or "biorational") pesticides, e.g:
    • M-Pede insecticidal soap;
    • horticultural oil,
    • insect growth regulator (many to choose from, see Greer, 2000);
• spray bottles for administering different treatments,
• dust mask or respirator (follow recommendations on pesticide labels).

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Experimental Procedure

1. Do your background research to make sure that you are knowledgeable about the terms, concepts, and questions above.
2. As you learned when doing your background research, accurate identification of the particular whitefly species is important, since there are differences in control strategies. Use the ID Key webpages from the Whitefly Knowldedgebase, or seek help from a local greenhouse expert or county agricultural extension agent.
3. Based on your background research, select 3–5 different treatments for testing.
4. Before any treatments, take photographs and perform counts to determine the level of whitefly infestation. Record the results in your lab notebook.
5. Clearly mark the different garden areas (or different branches of the same plant) for each treatment.
6. Prepare and apply the different treatments according to the manufacturer's instructions. Be sure to follow all safety instructions when spraying.
7. Use a plain water spray as a negative control.
8. Continue to perform whitefly counts and take photographs for each treatment area at regular intervals for two weeks. Record the results in your lab notebook.
9. Make graphs of the whitefly counts vs. time for each of the treatment areas.
10. Which treatment is most effective?

Variations

• Ladybugs (both adults and larvae) are natural predators of whitefly eggs and larvae. Can introduction of ladybugs control a whitefly infestation?
• Compare the cost effectiveness of different treatments. Which one delivers the best results per dollar?
• For a more advanced (and longer-term) project you could compare integrated pest management techniques vs. a single treatment. To do this, you would need multiple areas with similar infestations for testing (e.g., multiple fields, greenhouses, or your garden plus those of one or two friends).

• For more science project ideas in this area of science, see Zoology Project Ideas.

Credits

Andrew Olson, Ph.D., Science Buddies

Sources

This project is based on:

• Joyce, A.M., 2003. "The Effectiveness of Commercial Products vs. Home Remedies on Whitefly," California State Science Fair Abstract [accessed October 16, 2006] http://www.usc.edu/CSSF/History/2003/Projects/J1418.pdf.

Last edit date: 2011-10-26 12:00:00