Effect of Temperature on Maggot Behavior, Coursework Example

Introduction

The purpose of the experiment is to analyze the behavior of maggots in different temperature environments.  Behavioral studies of insects are an important aspect to science, especially in forensic entomology.  Maggots, which are the larvae from a broad range of different insect species, are used in studies of criminal investigations.  Behavioral studies of maggots can be important since these organisms are simple and react to changes in the environment through complex reflex reactions.  The reactions are important for these larvae to maintain position in a favorable environment.  Therefore, it is expected that all maggots would react similar with environmental change.

In the current study, the environmental condition and independent variable used is temperature, and the dependent variable is the distance of movement of the maggots.  Temperature is important in maggots as it determines the metabolic activity of maggots.  Maggots are considered “cold-blooded”, and therefore, temperature is an external environmental factor.  In addition, it has been found that maggots develop at a slower pace at lower temperatures and at a faster pace at higher temperatures.  Furthermore, it can be suggested that maggots move at a faster pace at optimum temperatures.  (Natural History Museum, 2014)

Since maggots are referred to as “cold-blooded” insects and therefore use the external temperature to determine the internal temperature and metabolism rate, the current study suggests predicts that the maggots will move at a faster pace with an increase in temperature.  It is hypothesized that at higher temperatures, the chemical metabolic reactions occurs more quickly due to a higher collision of particles and since metabolism provides the insects with energy, the maggots will in turn move more quickly.  However, extremely high temperatures can also results in the denaturation of proteins and enzymes, resulting in a lack of movement. The current experiment did not use abnormal high levels of temperature, and therefore, the lack of movement is not expected.

Materials

1 15cm by 15cm Piece of thick black paper

Sharp pencil

1 600cm3 Glass beaker

Ice- enough to fill the beaker up to 2cm from the top

2 Table lamps

Tripod

Mercury thermometer

9 Maggots

2 Petri dishes

Methods

A circle with a 1cm diameter was drawn of a blank sheet of paper and a second circle was drawn with a 10cm diameter within the circle, for each temperature sample.  Five different temperatures samples were used (0°C, 17°C, 25°C, 35°C, and 41°C).  All maggots were placed in a petri dish and placed in the refrigerator for 5 minutes.  For the cooler temperatures, ice was placed into a beaker with the piece of paper over that beaker, with the circles in the center.  For the warmer temperatures, the petri dish was placed under a table lamp for 5 minutes. In addition, the sheet of paper was set under a lamp and the temperature of the surface of the paper was recorded.  The temperature was taken using a thermometer and all temperature results were recorded for each beaker and at each lamp.  The maggots were placed inside the smaller circle and the distance at which the maggots moved was recorded at all temperatures and for all samples.

Results

The distance traveled by Maggots was measured at five different temperatures ranging from 0°C to 41°C.  The average distance (mm) was calculated for each temperature.  The results indicate that the maggots had a higher average distance traveled at 35°C.  In addition, the second highest average distance traveled was observed at 41°C.  However, the standard deviations for each of the samples were high at 41.4 and 53.3, respectively.  (Table 1)  As seen in Figure 1, there is an increase in distance traveled with increased temperatures, however a decline after 35°C.  The coolest temperature (0°C) had the smallest average distance at 93.6mm. (Table 1)

Discussion

The external factor of temperature was used to analyze the average distance maggots would reach under the given condition.  It was hypothesized that the maggots would move at higher temperatures since temperature is also related to the metabolic activity of maggots.  For instance, an increase in metabolism is expected at higher temperatures, creating more energy for the maggots to move. An increase in temperature can lead to an optimum temperature, which in turn increases the amount of kinetic energy and random movement of particles.   In this experiment, it was observed that the maggots traveled a greater distance at the 35°C temperature condition.  In addition, an increase in distance traveled was observed with the increase in temperature up until 35°C, and then a decrease was observed at 41°C.  It was also noted that at extremely high temperature conditions, the metabolic conditions in maggots may slow due to the denaturization of proteins.  It can therefore be suggested that the temperature at 41°C was the start of the decline in movement.

The current study suggests that the optimum temperature for maggot movement is observed at 35°C; however, there are some factors that were not presented into the experiment in order to support the results. A control temperature was not established.  The control temperature should have been room temperature and results should have been based off of these results.  Two temperature values were used that are near room temperatures values (°17 and °25); however, these temperatures were not set for the control.  In addition, the size of the maggots themselves were not recorded and compared.  It is possible that some of the maggots were larger, therefore, may require more energy to move.  Furthermore, the time at which the maggots took to move a certain distance was not recorded.  Although some of the samples moved greater distances, the time it took to travel was not recorded; therefore, the results of the experiment do not exhibit the rate at which the maggots traveled, only the distance.

Future experiments should incorporate a proper control setting, as well as an exact time for measurement for the distance traveled.  If relating movement to temperature, an established rate would correlate more when referring to metabolism.  Understanding the effects of different environmental conditions is important when studying larvae of insects in relation to forensic entomology.  Insect larvae can be found in decomposing living matter and can be used to estimate the time of death, and the time between death and discovery of the decaying body.  Therefore, understanding how temperature effects change movement can help forensic scientists understand larvae growth and movement in criminal investigations.  (Isaac et al., 2011)

References

Isaac, J., Deepu, M., Sathyan, P., Vargheese, G. (2011).  The use of insects in forensic investigations: An overview on the scope of forensic investigation.  J. Forensic Dent Sci. 3(2):89-91.

Natural History Museum.  (2014). On Maggots and Murders: Forensic Entomology.  Retrievedfrom:http://www.nhm.ac.uk/resources-rx/files/22feat_maggots_and_murders-3042.pdf.