Bean Beatle Competition Lab

RESULTS:

In the two control petri dish that consisted of 20 beans with eggs previously on them, the females laid two to three eggs. In the two control petri dish that consisted of 20 beans without eggs previously on them, the females laid to 2 to 6 eggs. The average number of eggs laid on the eggs that already had eggs on them was 1.25 eggs and the standard error was 0.5522. The average number of eggs laid on the eggs that did not already have eggs on them was 6.91667 and the standard error was 0.9728 (Figure 2). A comparative t-test was performed and from it the t-value, degrees of freedom, and p-value were determined. The t-value, for two-tailed distribution, was 2.20099, the degrees of freedom was 11, and the p-value was 0.00033 (Figure 1).

DISCUSSION:

Our hypothesis was accepted because the female bean beetles preferred to lay eggs on the beans without eggs rather than the beans with eggs already on them; therefore, the null hypothesis was rejected, because the p-value, 0.00033, was less than 0.05. This research is important because it tells us more about the ovipositional preferences of the female bean beetles. Larvae can’t move from the egg which is deposited, so the bean determined the future food resources that is available for their offspring, which would affect the the influence of the growth or reproduction; therefore, minimizing competition of resources between the offspring. It also important to know how if intraspecific competition will severely limit the rate of a population and there has been little published research done on this concept. In a similar experiment, the behavior of bean beetles was observed as well. The data also shows scramble competition, both in terms of the process of competition and its outcome. Their results showed that the more larvae per cowpea, the less emergence weight of the female or male producing a humped curve that associated with reproductive population stability. The experimenters didn’t expect intraspecific competition to limit the rapid build of numbers of the bean beetles (Giga & Smith 1991). For further research, we would test how different types of beans such as black-eyed peas vs. mung beans would affect the ovipositional preference and the intraspecific competition. This would show how to limit or max out the population of the certain species of bean beetle.

TABLES AND FIGURES:

Figure 1: A t-test was performed to determine whether the two variables, number of eggs laid on beans that already had eggs on them and number of eggs that did not already have beans laid on them, means differ by looking at the t-value and degrees of freedom to determine a p-value. The p-value is what is then used to determine whether the two variables means differ.

Figure 2: A graph comparing the average number of eggs laid on the beans that had eggs already laid on them and the average number of eggs laid on the beans that didn’t already have eggs on them.

LITERATURE CITED:

Giga D. Smith 12. 1991. Intraspection Competition in the Bean Weevils Callosobruchus Maculatus & Callosobruchus Vinodesiarus (Colcoprera: Bruchidae). J. Appli. Ecol. 28 918-929.