Animal Behaviour

Animal Behaviour

Biology 233

Winter 2007

Lab Section 38

By: Benson Chuong

T-Test

Raw Data

Time Spend on: Trial 1 Trial 2 Trial 3 Trial 4 Mean ± SEM

Dead Pupae 0 min 4 min 0 min 4 min 2 min ± 1.15 min

Live Pupae 25 min 30 min 19 min 28 min 25.5 min ± 2.40 min

Sum of Both Group Size = 8

Critical Value = 2.45

Calculate Value = 8.83

Critical Value < Calculated Value

Animal Behaviour

Hypothesis

In this experiment, we will be investigating the behaviour of a mated female jewel wasp (Nasonia vitripennis) when it is presented with a selection of hosts for it offspring. There will be one living pupae and one dead pupae available for the wasp to examine. It is hypothesis that the wasp will spend more time examining the live pupae, and less time examining the dead pupae. The wasp is expected to spend more time examining the living pupae because it will need to check the host's quality and determine a location for it to inject its eggs.

Results

Table 1: Amount of Time the Mated Female Jewel Wasp

Spends Around Different Pupa Types

Time Spend on: Mean ± SEM

Dead Pupae 2 min ± 1.15 min

Live Pupae 25.5 min ± 2.40 min

The data provided in Table 1 shows a significant time difference between how long the female wasp spent on the dead pupa compared to the live pupa (2 min ± 1.15 min vs. 25.5 min ± 2.40 min). The maximum amount of time of 25.5 min ± 2.40 min was spent on the live pupae, which acts as the control for this experiment. While the minimum amount of time of 2 min ± 1.15 min was spent on the dead pupae. The wasp was observed for a total of 30 minutes, any time that is not included in the table was time the wasp spent in its surroundings, not in contact with the pupae, for example walking around in the petri dish. On average, the female wasp spent over 13 times, the amount of time on the live pupae as it did on the dead pupae. The SEM value for the live timings was quite low; this shows that the data closely represents the population mean. On the other hand, the SEM values for the dead timings was high, this shows that the data does not closely represent the real mean. Upon graphing the data (Figure 1), we can see that the SEM bars do not overlap; this shows that the data for the time spent on the living pupae and the time spent on the dead can be considered different. Furthermore, a t-test performed on the data shows that the amount of time the female wasp spends on the living pupae is significantly more than the amount of time the female wasp spends on the dead pupae (25.5 min ± 2.40 min vs. 2 min ± 1.15 min; calculated t = 8.83, critical t = 2.45, sum of both group sizes = 8). Overall, the female allocates more of its time investigating the live pupae, the control, compared to the time it spends investigating the dead pupae.

Figure 1: Graph showing the Amount of Time the Mated Female Jewel Wasp

(Nasonia vitripennis) Spends on Different Types of Pupa.

Discussion

Female Jewel wasps (Nasonia vitripennis) are considered parasitic because they inject their fertilized eggs into the pupae of other fly species (Addy, et al., 2007). This requires mated females to search for a high quality host in order to deposits its eggs. In our hypothesis, we believe that the female will spend more of its time investigating the control pupae, which is the live pupa. This is supported in this experiment as we can see that the greater amount of time is spent on the live pupae (Figure 1). No unexpected or abnormal results were observed. Statistically, we can show, using a t-test, the time