Comparing Natural and Chemical Pesticides

Complexity level:	4
Time required:	Half hour to set up on two subsequent days. 10 - 15 minutes checking the plants every 3 days for 2 weeks. This experiment is best performed during spring or summer, when bugs and other pests are more likely to be found.
Material availability:	Everything you need for this science fair project will be available at a big-box retailer or large hardware store, as well as a grocery store.
Safety concerns:	General safety rules apply. You should take care with the hot water and chili peppers; protective gloves are recommended. An adult should be enlisted to assist you.

Hypothesis

Biopesticides will not protect plants as well as chemical pesticides.

Overview

Have you ever seen your parents spray a chemical on your summer tomato plants? If so, you have probably seen someone apply a pesticide, a chemical designed to keep pests - primarily insects - away from agricultural plants. Pests can cause serious problems for farmers by destroying their valuable crops, which can make our food more expensive because it becomes scarcer.

In recent years, a move toward biopesticides has been observed due to concerns over health problems caused by the use of chemicals. You can buy a traditional chemical pesticide at your local hardware store, but biopesticides are probably closer than you think, often found in your kitchen!

To determine the effectiveness of pesticides, experts look at plants to see if holes have been bored in their leaves or bite-marks are found on the flowers. Some insects will leave a sticky residue on the leaves, as well, or the bugs might actually be seen on the plant!

In this experiment, we will compare the effectiveness of three biopesticides - neem, onion and chili peppers - to a more traditional chemical pesticide. Remember that we will be using a control during this experiment to eliminate error from our experimental procedure.

Scientific Terms

Control, Pesticide, Biopesticide

Materials

5 small mature potted plants of the same type
1 chili pepper (finely chopped or pureed)
2 tbsp organic neem oil
1 large onion (finely chopped)
1 bottle chemical pesticide (targets aphids and beetles at minimum)
3 spray bottles
Rubber gloves
4 Bowls
Boiling water
liquid soap
Coffee filter
Funnel
Permanent marker
Plastic wrap

Procedure

Obtain your 5 plants. Label one plant with the word "Chili," one with "Neem," one with "Onion", one with "Chemical" and one with "Control."
Set aside the plants for the moment.
Begin by preparing the hot chili pepper spray. Place the chopped pieces of pepper in a bowl and cover them with about one cup of boiling water.
Prepare the neem spray. Put the neem oil into a bowl and mix with about a cup of warm (not boiling) water. Add a half a teaspoon of liquid soap to ensure the oil mixes with the water.
Prepare the onion spray. Put the chopped onion into a bowl and cover with a cup of boiling water.
Carefully cover the 3 bowls with plastic wrap.
Leave the onion and pepper spray to sit overnight in a refrigerator or storage cabinet.
The next day, take out the 3 solutions and the spray bottles.
Put a coffee filter inside of the funnel to make the chili pepper and onion sprays.
Pour the chili pepper solution through the funnel into a clean bowl.
Pour the solution from the bowl into one of the spray bottles.
Label that spray bottle "Chili."
Rinse out the funnel with water.
Repeat steps 9 - 12 with the onion spray, labeling the spray bottle "Onion."
To prepare the Neem spray, simply use a clean funnel to pour in the Neem oil mixture into an empty bottle and label the bottle "Neem".
Take the plants to a large designated outdoor area.
Take the plant labeled "Chili" aside (at least 10 feet away from the staging area) and spray it with the chili pepper solution. Set it at least 2 feet away from the other plants.
Repeat step 17 for the "Onion", "Neem" and "Chemical" plants.
Do not spray anything on the control.
Set the plants at least 2 feet away from each other in a straight line.
For the next 2 weeks, observe the plants every 3 days for signs of plant damage.
If it rains, reapply the spray using steps 17 and 18.
Record your observations in the table, mentioning whether you see any holes on the leaves and rating the extent of the damage from 1 - 10 (10 being the most damaged)

Day	Chili plant damage rating 1-10	Neem plant damage rating 1-10	Onion plant damage rating 1-10	Chemical plant damage rating 1-10	Control plant damage rating 1-10
1
2
3
4
5
6
7

Do you notice anything else about the plants?

References

McGraw-Hill. "Finding Natural Pesticide Substances." Retrieved from http://www.education.com/science-fair/article/finding-natural-pesticide-substances/

Experiment Central Science Resource Center. "Natural versus Synthetic: How do different types of pesticides compare against a pest?" Retrieved from http://www.galeschools.com/sci_try/pesticide.htm

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