Effect of Substrate Choice On Growth Of Mealworms Abstract: The experiment is designed to show which substrate A or B will better nourish a mealworm. A mealworm was placed in each substrate for a period of seven days and the change in mass from Day 1 to Day 7 was compared. The data was compiled and statistically analyzed. The experiment failed to reject the null hypotheses that there would be no difference in the two substrates regarding meal worm growth. The conclusion that there was a difference requires more experimentation to obtain additional information. Introduction:

Using the scientific method it is necessary to gain some knowledge about mealworms and the two different substrates. Mealworms are the larvae of Tenebrio molitor, commonly known as the darkling beetle. They are from the kingdom animalia and the class insecta. These mealworms are 1/2” to 3/4” long and have a slightly tough exterior useful for burrowing. They prefer to live in areas where moist organic matter is abundant. The beetles and larvae eat decaying leaves, sticks, and as composters eat dead insects and stored grains. (CEISO, The University of Arizona, 1997) Mealworms do not thrive in wet or moldy conditions.

Mealworms are easy to raise and multiply quite rapidly at 80 degrees F. Size is largely a matter of feed and temperature. (Ohio State University Extension, 2000) The purpose of the experiment is to find out how the choice of substrate A, oat bran or substrate B, peat moss will impact mealworm growth. Oat bran is the outer covering or bran of the oat grain and is a stored grain. Peat moss is a genus of between 151-350 species of mosses composed of the live part growing on top of a peat bog, and sphagnum peat moss, the decaying matter underneath.

Members of this genus can hold large quantities of water inside their cells; some species can hold up to 20 times their dry weight in water. (Wikipedia, 2009) Materials: Mealworm larvae Vial with a measurement line marked 4 cm from the vial bottom China marker used to mark vial Foam stopper Substrate A Substrate B Graduated pipette Pipette filler Tap water Metal tweezers Boat Balance Ruler Tape Plastic tray Incubator set to 28 degrees C Methods: Each student in the class was given a vial and stopper. Half of the class was assigned substrate A and the other half substrate B.

The vials were marked with a 4 cm marking and the assigned substrate (oat bran or peat moss) was added to the 4 cm line on each vial. Using the tweezers to gently pick up the worms we were sure to choose the feisty ones and place them gently into a boat. The balance was tared out and then the worm was placed into the boat on the balance. The initial mass of the worm to the nearest 0. 001g was then recorded in Table 2. 1 as Day 0 mass. Next, the graduated 1 ml pipette and filler was used to add 0. 5ml tap water to each vial. Lab Manual) One mealworm was placed in each prepared vial and the foam stopper was put into place. The vials were put into a labeled plastic container and placed into the incubator set at 28 degrees C. The mealworms remained in the incubator for 7 days. One week later, the mass of each mealworm was weighed to the nearest 0. 001g and recorded in Table 2. 1 as the final mass on Day 7. The total gain or loss of mass for each larva was calculated and recorded in the table. The data for the class was compiled and analyzed for the two substrates A and B. Results: See attached sheets

Discussion: The hypothesis that one substrate would be superior to another in nourishing the worms was not supported by the experiment results. The null hypothesis (Ho) is not rejected. The null hypothesis maintains that there is no difference between the two substrates. The alternate hypothesis (Ha) maintains that the two substrates are unequal. Statistical calculations were done to establish the P-value of . 684 for this experiment. The p-value refers to the statistical concept that if the p-value is less than the significance level (. 05) then the null hypothesis is rejected.

The lower the significance level the stronger the evidence. (Wikipedia, 2009) Low moisture, incorrect temperature and incorrect food will affect the growth of the mealworm. Is there an initial moisture variability in Substrate A and B and is the moisture retention the same in the two substrates over the seven day period? Some sources suggest adding vegetable pieces to the substrate to maintain moisture without saturation. (Ohioline, 2000) Oat Bran is thought to be a preferred nutrient for the mealworm. It is noted that mealworms prefer decaying plant matter, dead insects, feces, and stored grains. CISEO, University of Arizona, 1997) It is possible that the peat moss could have contained some of these components? Or is it likely that peat moss the decaying matter living on the underside of a bog, with its ability to hold large quantities of water inside their cells (some species can hold up to 20 times their dry weight in water) was better able to provide the water and decaying matter that the mealworms needed to thrive. (Wikipedia, 2009) Also, it should be noted that the experiment called for mealworm larva that weighed less than 0. 15 g.

All of the mealworms but two weighed more than 0. 15g and most significantly more. Could it be the larger the mealworms are the less they grow before they become pupa? This could explain why Group A had less overall growth as they were larger to begin with. Lastly, it is possible that some of the worms may have been weighed incorrectly or the data was entered incorrectly or both. There were two worms in the experiment whose weight increased 25 times the original weight. The experiment should be redone using smaller worms, verified weights and confirmed data entry.

References Cain, Cardenas, Donald-Whitney, Helgeson, McCulloch, Rice Weis, (2009). Biology 1406 & 1408 Lab Manual, Revised Edition 2008-2009. Reno, NV: Bent Tree Press. Unit 2-Scientific Method CISEO, University of Arizona, (1997). Darkling Beetle/Mealworm Information. Retrieved February 20, 2009, from The University of Arizona, The Center For Insect Science Education Outreach Web site: http://insected. arizona. edu/mealinfo. htm IB Source, (2/21/2009). IB Source. Retrieved February 21, 2009, from IB Source Quality Resources for the IB Curriculum Web site: www. b-source. com/osc/9780435994242. pdf Ohio State University Extension, (2000). Rearing Mealworms. Retrieved February 20, 2009, from The Ohio State University Fact Sheet Extension Web site: http://ohioline. osu. edu/hyg-fact/2000/2135. html Statistical Significance. (2009). Statistical Significance. In Wikipedia [Web]. Wikimedia Foundation. Retrieved 02/21/2009, from http://en. wikipedia. org/wiki/Statistical_significance Sphagnum. (2009). In Wikipedia [Web]. Retrieved 2/21/2009, from http://en. wikipedia. org/wiki/Peat_moss