Introduction: (Initial Observation)
While sitting outside after dark you may have noticed that varieties of insects are attracted by light bulbs and candles. What are the common properties of candles and light bulbs that attract insects? Both a candle flame and a light bulb have light and heat. Which of these two factors are attracting insects? Is it heat or it is the light that the insects are interested in?
In this project, you will investigate to determine if insects will be attracted to a light source or a non light heat source.
This study can help people control insects to maximize their benefits and reduce their harms. You may also use the results of this study to design an effective insect trap.
Warning: The experiment in this project requires using electric light bulbs. Adult supervision, support and assistance is required for running extension cords, connecting light bulbs and all other steps that may require exposure to heat or electricity.
Find out about insects, their habitat and life cycle. Read books, magazines or ask professionals who might know in order to learn about the factors that may attract certain insects. Look up an encyclopedia and the books that you may find about insects in your local library.
Keep track of where you got your information from.
Of course not all insects are attracted by the same factors.
Following are samples of information that you may find:
Plants That Attract Beneficial Insects
Nature is filled with “good bugs”, crawling and flying creatures whose diet consists mainly of the pests that ravage garden plants. Here is a list of those good bugs and the plants that they like to visit for food and shelter. Intersperse these plants among the “problem pest areas” in your yard. Remember, though: Many chemical sprays work on both bad and good bugs. To keep the good bugs in your yard, eliminate insecticide use in the areas where they live and work.
Make a Light Trap
A simple light trap can be made from a funnel, a round gallon can and a light. You can buy a large funnel or make one by cutting the bottom out of a gallon milk or detergent container. Place the funnel on the can as shown in the illustration, and suspend the light slightly above the funnel. Insects that fly into the light bulb fall down the funnel and are trapped in the can. The spout of the funnel should be large enough to let the insects drop through it easily, but not so large as to let the insects fly out again. A few strips of one inch wide newspaper in the can will give insects a place to hide so they are less likely to try to escape.
When getting the insects out of the trap, put the can and funnel together into your collection net before removing the funnel. This will prevent active insects from escaping.
PHYSIOLOGICAL RESPONSES OF INSECTS TO HEAT
Author(s): NEVEN LISA G
Postharvest quarantine treatments using high temperatures have been developed on various commodities. There are a wide range of insect pests that are the target of these treatments. In order to make heat treatments effective against these pests, the effects of high temperatures on insect physiology must be understood. Insects, being cold blooded, are particularly sensitive to heat. Nearly every system studied in insects has demonstrated sensitivity to heat. Studies on the effects of heat in insect metabolism demonstrate some adaptability to thermally challenging environments. Respiration, as to be expected, is also effected by heat. As the body temperature of the insect increases, there are concomitant increases in both metabolism and respiration up to a upper critical thermal limit. The effects of heat on the nervous and endocrine systems is another area where elevated temperatures wreck havoc. Changes in behavior and development have been documented as resulting from heat treatments. Among the most studied responses of insects to heat is the elicitation of heat shock proteins. The impact of these proteins on thermotolerance are still being investigated. Models of thermal damage leading to the death of the insect are discussed as well as current studies in describing the events of thermal death.
What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.
The purpose of this project is to determine if insects will be attracted to a light source or a non light heat source.
When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.
Independent variable (also known as manipulated variable) is the conditions that may attract insects. Possible values that are being tested are heat and light.
Dependent variable (also known as responding variable) is the number of insects that are attracted in each condition.
Controlled variables are weather temperature, outside light, and other factors that may attract insects such as foods.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
This is a sample hypothesis:
I think insects are attracted to ………….., and not a ………………
My hypothesis is based on my observation of …..
This is another sample hypothesis:
I think insects are attracted both to heat and light.
My hypothesis is based on my observation of ….. and based on my gathered information stating that ….
Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”
Experiment: Light or heat?
This experiment will test the attraction of insects to a light source and a heat source. You will make three traps, one with light, one with heat and the last one will be the control. The control will have neither light nor heat. You will count the number of insects in each trap after 4 hours.
- Get three identical round gallon cans or any similar container (metal or plastic).
- Use a large sheet of heavy paper or construction paper to make three funnels. Alternatively you may make funnels by cutting the bottoms of two large plastic cans.
- Place the funnels over the cans. Funnel allows the insects to enter the can when they fall, but makes it difficult for them to exit. This is a simple trap. You may also add some water to the bottom of all containers to make the trap more effective.
- Place both cans outside in the late afternoon where insects may fly. Keep them about 6 to 8 feet apart in identical positions.
- Label the cans as “Light”, “Heat” and “Control”.
- For the “light” trap hang a 40 watt light bulb above that. Adult help and support is required for this part. You may need to use some fixture to hold the light bulb about one foot above the funnel.
- For the “Heat” trap hang a 40 watt light bulb above that. Cover the light bulb with aluminum foil before you turn it on. Aluminum foil will stop the light, but will not stop the heat radiation.
- Do nothing with the control trap. It will not need heat or light.
- Turn on both lights with a remote switch.
- After 4 hours, turn off the lights (caution: they will remain hot for at least 5 minutes), remove the funnels and count the insects trapped in each can.
- Report the results and use them for your conclusion.
Your data table may look like this:
|Condition||Number of insects trapped|
For the light can, you may use a compact fluorescent light bulb that produces light without getting very hot.
For “Heat” can you may choose to purchase a heat lamp. If the heat lamp that you are using does not have much visible light, you may use it without aluminum foil.
Materials and Equipment:
List of material can be extracted from the experiment section. You will need to write your final list of material in your reports.
Results of Experiment (Observation):
Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.
No calculations are required.
Summary of Results:
Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.
It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
What color light attracts more insects? This can be the subject of another experiment.
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.
Visit your local library and find more information about insects and insect control. Write a list of your references here.