Transcript
Metabolic Rate of Gromphadorhina portentosa (Madagascar Hissing Cockroach) in Controlled Environments
Abstract This experiment was conducted in order to test the gas exchange or metabolism of the ectotherm; Gromphadorhina portentosa, commonly known as the Madagascar hissing cockroach. One (1)
G.portentosa was set in a clear experimental container and observed for approximately ten (1 ) minutes at a room temperature of !"o#$ %ollowing this observation the apparatus containing G.portentosa was submerged in cold water to provide a cold environment for the first run$ Then it was submerged in warm water to imitate a hot environment$ The carbon dioxide level and the temperature of the apparatus were observed for approximately ten (1 ) minutes in five (&) minute increments for both runs$ 'nder normal conditions such as the natural environment of G.portestosa carbon dioxide (#O!) and oxygen (O!) exchange increases as temperature increases allowing for more free movement$ The metabolism experiment proposed that in hotter temperatures the cockroach showed more gas exchange of #O! and also displayed more movement$ Introduction Metabolism is the totality of an organism(s chemical reactions to maintain life$ ) metabolic pathway usually comprises several steps such as a series of chemical reactions cataly*ed by en*ymes$ Thus the reactants of one reaction are the products of the previous one$ This cycle occurs repeatedly yielding processes for cell growth+ reproduction+ response to environment+ survival
mechanisms+ sustenance+ and maintenance of cell structure and integrity$ ,t is made up of two categoriescatabolism and anabolism$ #atabolism is the degradative pathway that breaks down complex
organic molecules such as fats+ carbohydrates+ and proteins into simpler molecules such as pyruvate+ #o!+ and .!O causing an oxidation reaction that releases free energy$ )nabolism is the constructive pathway that consumes energy to build complex molecules from simpler ones+ such as the formation of glucose from two pyruvate molecules+ which are sometimes called biosynthetic pathways$ The Madagascar hissing cockroach is an ectothermic insect+ which means it regulates its body temperature by exchanging heat with its surroundings unlike endothermic insects
that generate heat by internal metabolic pathways to maintain body temperature$ (#ampbell and /eece ! 0) G.portestosa(s natural environment is the tropical dry forest and tropical rainforest$
Their lifestyle includes the breaking down of decaying plant and animal matter and their usual diet includes rotting fruits and fungi$ They are categori*ed as herbivores$ They live in large colonies containing subsets of smaller colonies within the large colony$ One male will dominate and hold a territory with several females$ ,f another male enters+ it is pushed out of the territory by the dominate male$ %emales may come and go within these male dominated territories$ (%ull and .erreid 110") ,n the experimental examination of G.portestosa+ levels of #O! were tested at different temperatures of hot or cold environments$ ,t was predicted that+ with increased temperature metabolic exchange of #O! and O! would also increase thus allowing free movement of G.portentosa closely mimicking its natural environment$ This prediction was predicated by knowing a brief history and knowledge of the natural habitat of G.portestosa Methods Preparation G.portestosa used in the experiment was taken from a container where all the roaches were held and placed into a two liter clear container allowing for behavioral observations during incremental increasing and decreasing temperature changes$ ) 2ernier 3ab4uest instrument was used to analy*e the O! and #O! levels inside the apparatus by inserting probes through two holes on top of the apparatus yielding digital readings of O! and #O! levels at specified time intervals$ ,n this experiment the levels of #O! were of greater importance than the O! levels$ To evaluate a correlation between temperature and rate exchange a thermometer was placed inside the container to get the temperature readings at each time interval$
CO! Levels with Respect to Temperature in a Cold Environment The apparatus containing the O! and #O! probes and thermometer was placed on the table for a few minutes to get initial readings of #O! levels and temperature$ The initial temperature inside the container was !"o# and the initial level of #O! was $!!5 6$ 7ext+ we placed the apparatus into a tub of ice+ inducing a cold environment for G.portestosa$ This was our first run of the experiment$ The emission of gases were read as percentiles and recorded for ten (1 ) minutes with five (&) minute intervals$ The temperature was recorded at each time interval as well$ )ll data was recorded in lab notebooks for later usage$ %rom this data an average of O! and #O! levels was calculated$ CO! Levels with Respect to Temperature in a Hot Environment To prepare for run two (!)+ the ice was dumped out into a sink and moderately hot water was filled into the tub$ The apparatus was then placed on the table for a few minutes to obtain initial readings as done for run one (1)$ )fter obtaining initial readings+ the apparatus was placed into the tub of hot water and was observed for the next ten minutes as well$ To prevent possible damage to the probes a book was used to keep the apparatus in place and prevent it from floating and tipping over$ )s in run one (1) the percentage of #O! level was recorded every five minutes along with the temperature$ Movement of the roach was also observed and noted$ )ll data was recorded in lab notebooks for later usage$ %rom this data the average #O! and O! levels were calculated$ 8ata from both runs were transferred from lab notebooks and prepared in Microsoft 9xcel$ Results
CO2Levels with Respect to Temperature in a Cold Environment The initial temperature of the container was !"o# and the initial #O! level $!!5 6$ 9very five minutes the analy*ed data showed that as temperature decreased+ levels of #O! increased$ Movement of G.portentosa was minimal during the initial readings and to about ten (1 ) minutes into the experiment$ Movement was observed approximately ten (1 ) minutes into the experiment after the container was slanted slightly$ :hen the apparatus was slanted an increase in #O! levels was observed$ Movement stopped around twelve (1!) minutes$ Movement of G.portentosa was pertinent in this experiment but was observed and recorded in this report$ ,n ;raph 1+ the relationship between temperature and #O! level is depicted to show the increase in #O! level as temperatures decreased$
Temperature © vs CO2 level (ppm) 0.25 0.2 0.15 0.1 0.05 0 0 5 Temperature (c) 10 Temperature © vs CO2 level (ppm)
Graph 1. Relationship between temperature I degree Celsius and CO 2 (%) level in a cold environment.
,n Table 1+ the emission of #O! along with the temperature at each time interval is shown$ Table 1 #O! levels at various temperatures in a cold environment$
CO2 level (ppm)
Time Ela!sed (mins) & 1
Tem!erature (oC) 1 0 <
C"# $evel (%) $1&"! $1<>1 $11><
The calculated average change in #O! (6) level per degree #elsius of change in temperature was $ 11<&6$ These calculations were derived by taking the total change in the #O! percentage and dividing it by the total change in temperature$ CO! Levels with Respect to Temperature in a Hot Environment ,nitial temperature for this run was "!o# with initial readings of #O! level at $15"&6$ 9very five minutes the observed data showed that an increase in temperature was directly proportional to an increase in #O! levels$ Movement observed was very minimal during the time period between *ero ( ) and seven (<) minutes of the experiment however towards the end of the ten (1 ) minute period the cockroach was moving fast and freely about the apparatus$ =elow in Table !+ the emission of #O! gases are shown as well as the temperature for each five (&) minute interval$
Table # O! and #O! levels at various temperatures in moderately hot temperatures$
Time Ela!sed (mins) & 1
Tem!erature (oC) "! "> "!
C"# $evel (%) $15"& $1"&> $1&&<
,n ;raph !+ the relationship between temperature and #O! (6) level is graphed to easily view the rise in #O! level as temperature in degree #elsius increased$
Temperature © vs. CO2 level (ppm) 0.17 0.165 CO2 level % (ppm) 0.16 0.155 0.15 0.145 0.14 41.5 Temperature © vs. CO2 level (ppm)
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Tem perature (C)
&ra!h ' /elationship between temperature in degree #elsius and #O! (6) level in a hot environment$
The calculated average change in #O! (6) level per degree #elsius of change in temperature was $ 1"06$ These calculations were derived by taking the total change in O! or the #O! percentage and dividing it by the total change in temperature$
(iscussion The stated hypothesis said+ the higher the temperature the more #O! is going to be exchanged and the roach will be freely moving because this closely mimics its natural environment$ )s a result+ the prediction was proven correct+ through observation and from the data collected$ ,n the hot environment+ O! and #O! levels increased as the temperature inside the apparatus increased$ ,n the cold environment+ O! and #O! levels decreased as temperature decreased$ )ll data collected from this experiment and presented in this report fail to re?ect the null hypothesis stating that that as temperature increases #O! levels increase allowing free movement of G.portentosa$ 8uring observation of G.portentosa when placed in a cold environment it was apparent that the insect did not acclimate well to the cold environment evidenced by minimal movement and gas exchange and a hissing noise heard while in the colder environment$ ,n the warmer environment G.portentosa acclimated very well as evidenced by observed increase in O! and #O! exchange+ increased movement and a lack of hissing$ )lthough the movement of the cockroach was not relevant to the metabolic rate or gas exchange+ G.portentosa showed more movement in the warmer environment$ )ll graphs and tables in this report give a visual relationship between levels of #O! at varying temperatures$ 9xperimental data and observation was compared to others in the laboratory+ and seemed to yield the same results; hotter
temperatures corresponded to more O! and #O! gas exchange$ This correlation between gas exchange and temperature includes but is not limited to serving as an indicator of G.portentosa(s ability to acclimate to certain environments$ %or example O! enters the cockroach through tiny breathing tubes called tracheae to all of the body parts #O! is then released$ (=radley and #ontreras ! 1)$ The cockroach has the ability to press air through its spiracles to make a hissing
noise as a sign of aggression+ hence the name of the cockroach$ ;as exchange increases when the cockroach is comfortable with the environmental conditions regardless if the conditions are in a laboratory setting or its natural environment (=lackburn and #hown ! 0)$ 8uring this
experiment there were no ma?or complications$ .owever for future experiments results may be improved if the sample si*e were increased$ ,n addition to sample si*e the sub?ect should not only be observed at room temperature but should also be observed for a period of time after being aggravated+ inducing hissing$ )t this time gas exchange should be measured before the manipulating the temperature$ =y doing this it would be possible to show whether or not aggravation and temperature are dependant or independent of each other in relationship to gas exchange$
$iterature Cited )rticles=lackburn Tim M+ #hown @teven 3+ Marais 9lrike+ Terblanche Aohn @+ :hite #raig /$ ! 0$ @caling of gas exchange cycle fre4uency in insects$ =iol 3ett$ "(1)- 1!B5> p$
%ull /obert A+ .erreid ,, #lyde %$ 110"$ #ockroaches on a treadmill- )erobic running$ Aournal of ,nsect Chysiology$ > (&)->1&B" &$ The =ig Doo E,nternetF$ #! 1 $ Magnolia (TG); Ecited ! 1 March ! 1 F$ )vailable from- http-HHwww$thebig*oo$comH)nimalsHMadagascarI.issingI#ockroach$asp