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The affect of caffiene on mealworms Essay


Caffeine is a popular drug that is consumed frequently by children. It is found in common foods like tea, cola and chocolate. Since the children are still growing and developing, the consumption of caffeine may negatively affect physical development.


Does Caffeine affect the growth and development of mealworms?


About 85% of Americans consume caffeine in one form or another every single day. Caffeine is found in popular items such as coffee, tea, cola, and chocolate and it has been linked to depressing appetite (Weinberg and Bealer, xvi). Caffeine is America’s most popular drug by far and the percentage of Americans that consume caffeine is more than all other drugs put together (Harris, 71). More than half of all American adults consume more than 300 milligrams (mg) of caffeine every day. Many people cannot go through a morning without a cup of coffee because caffeine is an addictive drug. When caffeine was first discovered it was considered a medicine (Weinberg and Bealer, xii).

Caffeine is a chemical compound that is composed of the 4 most common elements, carbon, hydrogen, nitrogen, and oxygen. The formula for caffeine is, C8 H10 N4 O2, which means each caffeine molecule is made up of 8 carbon atoms, 10 hydrogen atoms, 4 nitrogen atoms, and 2 oxygen atoms (Weinberg and Bealer, 216). Caffeine crystallizes into long white, needlelike crystals (Wagner, 365). Pure caffeine is bitter and is highly toxic. It is a white powder that is soluble in boiling water. Caffeine is a central nervous system stimulant and an analeptic, a drug that restores strength to the body. After caffeine is ingested it is quickly absorbed into the bloodstream. The concentration of caffeine in the blood reaches its peak 30-60 minutes after it is ingested and most of it is gone after 12 hours (Weinberg and Bealer, xiii).

In moderation caffeine produces positive effects. Caffeine is a stimulant to the heart and it also it increases urine production. It is used to provide a boost of energy or alertness (Brain, 2004, http://home.howstuffworks.com/caffeine1.htm). Caffeine makes the neural cells fire away, which makes the heart beat faster, the mind focus better, and the rate of breathing increase (Harris, 71). It uses the same mechanisms that cocaine and heroin use to stimulate the brain, although it is milder (Brain, 2004, http://home.howstuffworks.com/caffeine1.htm).

Mealworms are the larvae stage of the darkling beetle. They are wormlike and their body is hardened for burrowing. Mealworms have a strong golden exoskeleton and are cylindrical in shape (http://insected.arizona.edu/mealinfo.htm). Mealworms have all the basic parts that all insects have. They have 6 legs, 3 body parts, and 2 antennae. The first segments of their wormlike body are the head, the middle segments are the thorax, and the end segments are the abdomen (Mosbacker, 2004, http://www.uen.org/utahlink/activities/view_activity.cgi?activity_id=3022).


For this experiment, three groups of mealworms were tested. The first group was the control group that was not exposed to caffeine, the second group was given 200g of caffeine, and the third group had 800g. The third group was given four times the amount of group two

because it was thought that any developmental differences would be more obvious.

To begin the experiment, first the caffeine tablets were dissolved in water. Next, oatmeal flakes were cooked in the caffeinated water so that all the oatmeal would be equally caffeinated. Then, the oatmeal was chopped up into small pieces because it came out of the oven in clumps and the goal was to make it a more natural environment for the mealworms. For the control group the oatmeal still went through the whole process of being cooked and then heated in order to keep the control group the same as the test groups. The control group was used to compare the different growth rates with caffeine to that of regular mealworms that had not been given caffeine. For this experiment the necessary materials used are: 150 mealworms, 3 plastic containers, a metric ruler, oatmeal, and caffeine pills. To perform the experiment, follow the procedure below:

1) Get mealworms

2) Pick out 75 mealworms that are the closest in size

3) Measure all the mealworms and write down all the sizes (in mm), then average the size of 3 groups of 25

4) Get 3 plastic containers and poke small holes in the top

5) Put 25 in mealworms in each container

6) Dissolve a caffeine tablet (200 mg) in 150 ml of water

7) Mix the dissolved caffeine water with 160 ml of oatmeal

8) Cook it on low until all the water was absorbed into the oatmeal

9) Then spread out the oatmeal on a cookie tray and cook it for 90 minutes at 107 degrees Celsius

10) Then take the oatmeal and chop it up in a blender to make it finer

11) Place this oatmeal in one container and label it 200 mg caffeine

12) Repeat steps 6-10, once with 4 caffeine pills (800 mg) and once without any caffeine pills, which is the control group and label those containers accordingly

13) Measure the length of the mealworms every 2 weeks, find the average size for each container, and count the number of mealworms that develop into pupa

14) Observe the any changes in the mealworms


At the beginning of the experiment the average of all the mealworms in each container was 21mm. At the end of the experiment the control group grew to 29.54mm, an average increase of 8.54mm. The group with 200mg of caffeine grew to 27.73mm, an average increase of 6.73. The group that received 800mg of caffeine grew to 27.14mm, an average increase of 6.14 (See Figure 1). Also, the control group had the most number of mealworms that developed into the pupa stage, with 14, whereas the mealworms who received 200mg of caffeine had 8, and the ones that received 800mg of caffeine had 6 (Figure 2).


As seen in Figure 3, by the end of the experiment, the mealworms who received 200 mg of caffeine showed 77.4% of the growth of the control group. The mealworms ingesting 800 mg of caffeine showed 71.6% of the growth of the control group. Although the mealworms without caffeine were the biggest and the ones with the most caffeine were the smallest, due to the results of a standard statistical test called Analysis of Variation (ANOVA), which was performed, the test suggested that the caffeine had no effect on the growth of the mealworms (Table 1). A higher percentage (93%) of mealworms in the control group pupated compared to the 200 mg (73%) and 800 mg groups (67%), however the difference was not significant (Chi-square = 3.03, df = 2, p = 0.22).


Although during the course of this experiment, it appears that caffeine slowed the growth and development of the mealworms. However, other experiments with caffeine on living things had mixed results. The statistical tests (ANOVA, Chi-square) that were preformed on the data indicate that the difference was not significant enough to prove that caffeine had any affect on the growth and development of mealworms.


In performing this experiment, it was observed that the mealworms with the most caffeine were eating a considerable amount more than those of the other two groups. Since the amount of food was not measured in the beginning of the experiment, it cannot be determined whether caffeine increased their appetite. A good follow up study would be to test whether caffeine increases the appetite of mealworms.

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