The effect of temperature on Blow-fly larvae
The insects that have been most extensively studied in relation to their forensic uses are the blowflies members of the Calliphoridae fly family in particular their larvae or maggots, because they are insects most commonly associated with corpses widely known the colonization of them and their development rates are used to estimatethe post-mortem interval. The major external factor is temperature, a parameter with which metabolic activity of maggots, which are cold-blooded, the temperature is strongly correlated with the burrowing, growth and development of the blowflies. Overall high temperatures speed up the development of the species, low temperatures delays the process of the development of the species likewise hightemperatures produce chemical reactions such as metabolism development more quickly due to the increased kinetic energy of the particle. These particles are moving more quickly and therefore more collisions occur causing a reaction.
Forensic entomology is a science that studies the relations between insects and cadaverous decomposition. This science is a useful tool to resolve mysteries aroundcorpses found in particularly circumstances. In many countries this science is extensive and is used as legal tool and fundamental point of crime scenes. The metamorphoses or life cycle of these flies consist of four stages which are egg, larval, pupa and adult fly. (Fig: 1)
Our experiment was setup to investigate the effects of temperature of blowfly larvae, observing the changes as temperaturesincrease, starting from 10ºC and gradually rising the temperature to reach 30ºC with the help of the following equipment. (Fig: 2)
Fig: 1 Life Cycle of the flies
As temperature increases the rate of activity of the maggots increases are more energy will be produce therefore maggots will move more quickly since their faster rate of metabolism provides them with the energy to doso. However, as very high temperatures, up to 38ºC there will most likely be a decrease in the metabolic rate due to the denaturation of Enzymes. Therefore, it will be expected that a higher temperatures, maggot will move more slowly, once they could not be provide with as much energy from metabolism.
Divide the interior base of a small beaker in half with a black line and place fivemaggots inside. The black line will serve to count the number of maggots that cross it, (the crossing can take place from any direction in any order). With the larger beaker, fill it with tap water about half way or a bit less, making sure the small beaker can fit inside the larger beaker and not spill any water into the small beaker where your five maggot are. You can change the water temperatureof the big beaker from low to high by adding ice or hot water. Measures with the thermometer until you reach your desired temperature. You should also measure the temperature of the small beaker, where your maggots are, which is effected by the water temperature of the big beaker. Start with the ambient temperature and gradually increase or decrease the temperature to achieve the requiredtemperature of 10ºC, 15ºC, 21ºC, 25ºC, 30ºC. Record the time in minutes to complete the five minute period when the maggots cross the black line per each temperature giving a time interval to start with a new temperature and re measuring the big beaker and the small beaker to obtain the new temperature.
As the temperature increasing, the rate of the activity of the maggots increases, thereforethey crossed the black line much faster and much times. The increase of rate activity can be determined by the Q10 law. As the temperature decrease the activity rate was lower and causes the maggot to move less. The low temperature did not allow the maggot to move quickly as they did with the high temperature therefore they crossed the black line in less time.
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