House Cricket Experiment
The topic of house cricket aggression in response to residency has been previously studied. (Alexander 1961) split this aggression behavior into five levels: 1) no aggression, dominance, or retreat; 2) no aggression with a retreat by one cricket; 3) mild one-sided aggression with mild repercussion; 4) moderate to intense aggression from both crickets; or 5) sustained combat. Interestingly, in Polistes wasps (Pardi 1948a), Sphecius wasps (Mr Norman Lin, personal communication), and crayfish (Bovbjerg 1953; Lowe 1956) aggressive behavior has been split into four or five levels. (Alexander 1961)
The experimental organism in this experiment was Acheta ...view middle of the document...
The study organism used was Acheta domesticus. Each group had six house crickets that were in separate containers. The containers were plastic and 18 by 15 by 6 centimeters long. Prior to the experiment being performed, the crickets had spent a week in these residencies. Along with the crickets in the plastic containers, there was wet pieces of paper towel and a slice of carrot.
The procedure started with placing the intruder cricket into another cricket’s residence. The intruder was distinguished from the resident by marking its body with a colored marker provided for the experiment. Once the intruder was in the container, a trial of ten minutes started. The object was to tally the winner each time the two crickets interacted in aggressive behavior. The loser was determined by which cricket backed up from the interaction first. After the ten minutes were up, the winner of the trial was the cricket with the most tallies. If the score was tied, the crickets were watched for an additional minute. This procedure was repeated twice for the remaining four crickets.
A Chi-square test was used for hypothesis testing. This is used to determine that the observed number of wins of the resident from the trials is different from what would be observed by chance. The null hypothesis was observed wins will be equal to that expected by chance. On the other hand, the alternative hypothesis was observed wins will not be equal to that expected by chance. The class’ hypothesis was proven correct that resident male crickets have a greater motivation to defend their territory and that they had more wins over the intruders.
The statistical test used in this experiment was a Chi-square test that measured the goodness of fit. There were 254 trials performed overall for the experiment. The sample was 508. For the resident crickets, it was expected that the cricket would win 127 times. The observed value was calculated to be 159 wins. The intruder cricket was also expected to win 127 times but the actual value was calculated to be 95. The Chi-square value was 16.126 and there was 1 degree of freedom. The p-value was less than 0.0001. This rejected the null hypothesis as the value was less than 0.05.
This experiment helped further investigate and understand house cricket behavior with respect to residency. It was found that the null hypothesis that the number of observed wins of the resident cricket will be equal to 50 percent is incorrect. The alternative hypothesis was proven correct during the Chi-squared testing.
However there were a few limitations on the present study. First, it was performed in a classroom with minimal resources to use. The class was only able to study the crickets for a couple of hours instead of several weeks as is usually done in a lab. Next, the same group of crickets were used for every lab during the week. Therefore, by the...