What is the Most Effective Treatment for Whitefly Infestations on Plants?
Abstract
Whiteflies are a group of closely related insect species whose larvae live on plants. Like aphids, they suck nutrients from the plant's circulatory system. What is the most effective method for fighting a whitefly infestation in your garden? This project has some ideas for you to try.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.
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.
Share your story with Science Buddies!
Last edit date: 2013-01-10
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 and Concepts
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);
- biopesticides, e.g.:
- spray bottles for administering different treatments,
- dust mask or respirator (follow recommendations on pesticide labels).
Disclaimer: Science Buddies occasionally provides information (such as part numbers, supplier names, and supplier weblinks) to assist our users in locating specialty items for individual projects. The information is provided solely as a convenience to our users. We do our best to make sure that part numbers and descriptions are accurate when first listed. However, since part numbers do change as items are obsoleted or improved, please send us an email if you run across any parts that are no longer available. We also do our best to make sure that any listed supplier provides prompt, courteous service. Science Buddies receives no consideration, financial or otherwise, from suppliers for these listings. (The sole exception is any Amazon.com link.) If you have any comments (positive or negative) related to purchases you've made for science fair projects from recommendations on our site, please let us know. Write to us at scibuddy@sciencebuddies.org.
Share your story with Science Buddies!
Experimental Procedure
- Do your background research to make sure that you are knowledgeable about the terms, concepts, and questions above.
- 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.
- Based on your background research, select 3–5 different treatments for testing.
- Before any treatments, take photographs and perform counts to determine the level of whitefly infestation. Record the results in your lab notebook.
- Clearly mark the different garden areas (or different branches of the same plant) for each treatment.
- Prepare and apply the different treatments according to the manufacturer's instructions. Be sure to follow all safety instructions when spraying.
- Use a plain water spray as a negative control.
- 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.
- Make graphs of the whitefly counts vs. time for each of the treatment areas.
- Which treatment is most effective?
Share your story with Science Buddies!
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).
Share your story with Science Buddies!
Ask an Expert
The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.Ask an Expert
Related Links
If you like this project, you might enjoy exploring these related careers:

Agricultural Technician
As the world's population grows larger, it is important to improve the quality and yield of food crops and animal food sources. Agricultural technicians work in the forefront of this very important research area by helping scientists conduct novel experiments. If you would like to combine technology with the desire to see things grow, then read further to learn more about this exciting career. Read more






