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Abby SoltisInsect Behavior 3/29/ 2012

Behavior of the Female Madagascar Hissing Cockroach: Female Only versus Male and Female Social Contexts

Introduction

Females throughout the animal kingdom are frequently confronted with female only

and male/female social situations, where behavior is variable. Female humans exhibit

differences in behavior in these social contexts as well. In the presence of females,

males have a tendency to produce different signals than in the presence of only males, in

the hopes of attracting a mate (Clark and Moore, 1995), but does female differ in the

presence of males and how does female behavior relate to sexual selection?

Little is known about how females act in the presence of males or in female only

social contexts in the case of the Madagascar hissing cockroach. Studies have been

done regarding social behavior in regards to aggregation (Varadinova et al., 2010) and

sexual signaling in males (Clark and Moore, 1995; Logue et al., 2009). The primary

question we like to answer in this study is does female cockroach behavior differ between

same sex and mixed sex social contexts? I hypothesized that females will be more active

in the presence of males. I predict that females will exhibit more active behaviors in the

presence of males and females and that females will exhibit less active behaviors in the

presence of only females. This will be due to female-female competition for finding a

mate, as well as other the process of a female choosing a male. As a secondary question

we looked at the question is anti-predator behavior in females related to body size? I

hypothesized that smaller females have a quicker anti-predator behavior response

because they cannot scare away predators with their size. I predicted that smaller


females will take less time to flip over after being placed on their back and larger females

will take more time to flip over after being placed on their back.

According to National Geographic the Madagascar hissing cockroach is originally

found in Madagascar, are oval-shaped and brown. The live 2-5 years in the wild and are

usually 2-3 inches long. They have no wings only 1 set of antennae. Males present

aggressive behavior toward one-another and often hiss while fighting. Hissing is also

used in mating and as an alarm response. They make a hissing noise by expelling air

through their breathing holes. Behavior in female Madagascar hissing cockroaches is

largely unstudied.

Materials and Methods

1. Study Organism and Methods

The organism of study are 24 female Madagascar hissing cockroaches obtained

from KenTheBugGuy.com, a company in California. The cockroaches were kept in large

terrariums (approximately 25cmX 50cmX 30cm) with 6 idividuals per terrarium and fed

pulverized and moistened dog food as well as apples, bananas, and carrots. The

cockroaches were kept on a 12hour-reversed night/ day cycle, where 9am-9pm was

night. The experiments were performed March 1st and 4th 2012 at Butler University. The

study organisms were labeled with a letter of the alphabet. The male Madagascar hissing

cockroaches were labeled with numbers.

In order to determine the state and event behaviors we wanted to study we did

three things. First, we identified the behaviors used in Logue et al., 2009 and discussed


with colleagues whether the behaviors would be relevant to female cockroaches. Then

we observed the cockroaches in female only groups of 6 in a darkened room, illuminated

with red light and performed an ethogram of observed behaviors. Thirdly, we came

together as colleagues and discussed which state and event behaviors we wanted to

observe. The chosen state and event behaviors and definitions are illustrated in Tables 1

and 2.

During the first data collection day, March 1st, we performed scan and focal

sampling on groups of female only cockroaches split into groups of 6 into 4 different

terrariums. The cockroaches were observed in a dark room, where red light was the only

light source. For focal sampling, each of the 24 cockroaches were observed individually

for 5 minutes and each behavior and the corresponding length of time was noted. If an

event behavior was observed it was noted during the state behavior in which it occurred.

If the behavior was one not listed in Tables 1 or 2 it was labeled as X for other and then

described. For scan sampling each group of 6 cockroaches were observed every 5

minutes for 15 minutes and at each 5 minute interval the state behavior of each individual

was noted.

On the second collection day, March 4th, the same scan and focal sampling were

performed as described above with a male/female mixed treatment. 3 females were

mixed with 3 males and the behavior of the 24 female cockroaches was observed. For

scan sampling the same number of scans was done except 2 scans were done on each

terrarium, instead of the previous 4 scans, so the number of scans remains the same.

2. Statistical Analysis


Does female cockroach behavior differ between same sex and mixed sex social

contexts? To answer this question we looked a the state behaviors in two different ways:

2.1 Budget Time Analysis

First, we used the focal sampling data to determine how long each individual spent

doing each behavior. Then, we graphed the mean proportion of time spent in each

behavior for the female only and the male/female treatments using the statistical program

SPSS 17.0. We could not do a two-way ANOVA due to the presence of several 0’s in the

data. The graph (figure 1) showed differences in how the female cockroaches spent their

time in the female only group or the male/female mixed group.

Secondly, we used a Chi square test for independence test to determine whether

an association exists between the two treatments using our scan sampling data using

excel. Essentially we tested whether one of the 3 behaviors was more or less associated

with a female only or male/female social context. We formulated a null hypothesis that

there is no difference between the proportion of observed state behaviors in the female

only and male/female social context. Our alternative hypothesis is that there is a

difference between the proportion of observed state behaviors. We calculated a p-value

for this chi-square test.

Thirdly, we again used our scan sampling data to construct a graph (figure 2) that

shows the proportion of observations for each behavior in the female only and

male/female social contexts.

2.2 Single Behavior Analysis


In order to analyze the average amount of time spent on each specific behavior in

female only and male/female social contexts we used the Wilcoxon Signed Rank test

using our focal data. We tested each behavior: feeding standing still active, standing still

not active and walking separately and calculated a p-value. We used the null hypothesis

that there is no difference in the average amount of time spent performing the behavior in

the female only and male/female social contexts. We used the alternative hypothesis that

there is a difference in the average amount of time spent performing the behavior in the

female only and male/female social contexts. These are illustrated in Tables 3-6.

3. Side Project

As a side project we asked the question: Is anti-predatory behavior in females

related to body length? In order to do this we tested two anti-predator behaviors: Hissing

and latency to flip in correlation with body length. First we tested whether or not each of

the 24 female cockroaches hissed when touched by an instructor and compared that with

body length. We used a Mann Whitney U test to find out if there is a difference in length

between the hissing and no hissing group. Our null hypothesis is that there is no

difference in body length between the hissing versus no hissing females. Our alternative

hypothesis is that there is a difference in body length in the hissing versus no hissing

females. The results are shown in Table 7. Secondly, we tested whether body length

influenced the time it took for the cockroach to upright itself. We did this by turning the

cockroach upside down and measuring the time it took to right itself. Our independent

variable was body length and our dependent variable was flip time. We performed a

regression using an ANOVA. The results are located in Table 8.


Results

2.1 Budget Analysis

Figure 1 depicts the mean proportion of time spent in each behavior for the female

only and the male/female treatments. The graph shows more time spent feeding,

standing not active and walking in female only treatment in comparison with the

male/female treatment. The graph also shows more time spent standing active in the

male/female treatment than the female only treatment. The error bars overlap between

treatments for each behavior.

Secondly we used a Chi square test for independence test to determine whether

an association exists between the two treatments using our scan sampling data. We

formulated a null hypothesis that there is no difference between the proportion of

observed state behaviors in the female only and male/female social context. The Chi

Square Test failed to reject the null hypothesis (Chi-square test statistic= 2186, N= 139,

and P= 0.335).

Figure 2 shows the proportion of observations for each behavior in the female only

and male/female social contexts. This graph shows that the proportion of observations for

feeding and standing not active is higher in the female only treatment when compared to

the male/female treatment. The graph also shows that the proportion of observations for

standing active is higher in the male/female treatment when compared to the female only

treatment.

2.2. Single Behavior Analysis




using our focal data.

For the Feeding behavior in Table 3, our null hypothesis that there is no difference

in the average amount of time spent feeding in the female only and male/female social

contexts. The Wilcoxon rank test could not reject this null hypothesis (Z= -1.826, N=24,

P= .068).

For the standing still active behavior in Table 4, our null hypothesis that there is no

difference in the average amount of time spent standing still active in the female only and

male/female social contexts. The Wilcoxon rank test could not reject this null hypothesis

(Z= -1.591, N=24, P= .112).

For the standing still not active behavior in Table 5, our null hypothesis that there

is no difference in the average amount of time spent standing still not active in the female

only and male/female social contexts. The Wilcoxon rank test could not reject this null

hypothesis (Z= -.855, N=24, P= .392).

For the walking behavior in Table 6, our null hypothesis that there is no difference

in the average amount of time spent walking in the female only and male/female social

contexts. The Wilcoxon rank test could not reject this null hypothesis (Z= -1.601, N=24,

P= .109).

3. Side Project


In Table 7, we used a Mann Whitney U test to find out if there is a difference in

length between the hissing and no hissing group. Our null hypothesis is that there is no

difference in body length between the hissing versus no hissing females. The Mann

Whitney U test could not reject this null hypothesis (Z=-.391, N= 24, P=.696).

Secondly, we tested whether body length influenced the time it took for the

cockroach to upright itself. We did this by turning the cockroach upside down and

measuring the time it took to right itself. Our independent variable was body length and

our dependent variable was flip time. We performed a regression using an ANOVA. The

ANOVA regression showed no relationship between the body length and latency to flip (F

Value= .819, DF= 23, sig value= .375).

Discussion

2.1 Budget Analysis

We used a Chi square test for independence test and determined that we cannot

assume there is a difference between the proportions of observed states for the female

only and male/female control groups. The P-value largely exceeds the .05 boundary for

significance, but by looking at the graphs (Figures 1 and 2) produced by the scan and

focal sampling data we can see that there is an association between the two. Both

graphs show that the state behaviors feeding and standing not active occur for more time

and in a larger proportion of observations in the female only than the male/female

treatment group. Similarly, both figures 1 and 2 show an increase in the standing active

behavior of the male/female treatment group when compared to the female only


treatment group. This data shows a trend, even if there is any statically significant

evidence.

2.2. Single Behavior Analysis



using our focal data. Unfortunately, none of these behaviors turned out to be significant,

but feeding (P=.068, Table 3), standing still (P=.112, Table 4), and walking (P=.109,

Table 6) gave p-values close to significance. This suggests that further testing would be

beneficial.

3. Side Project

For the side project the Mann Whitney U and the regression tests showed no

results. The p-value was so high that it is unlikely that new tests would yield different

results and the regression provided no better evidence that body length and anti-

predatory behaviors. This could simply mean that body length has little to do with getting

away from predators for female cockroaches. While body size does have an effect on

male cockroaches in regards to predatory-response, it is necessary to look into other

mechanisms for females.

Summary

The primary question we wanted to answer in this study is does female cockroach

behavior differ between same sex and mixed sex social contexts? We had no statistically

significant data to support that behaviors differ between the 2 social contexts, but the


trends in the data point out that more research is worthwhile. I hypothesized that females

will be more active in the presence of males. I predicted that females will exhibit more

active behaviors in the presence of males and females and that females will exhibit less

active behaviors in the presence of only females. The data trends show that there is more

standing active behavior in the male/female treatment group than the female only group.

This could mean that females are more alert in the presence of a potential mate and that

feeding is less important when males are present. This alertness could mean that

females are gathering information in order to choose a mate or they are gathering

information about their opponent females.

Some of the variables that could have skewed the data are time of day. The first

data was collected in the afternoon, while the second set of data was collected in the

morning. Also, not all behaviors were observed, which led to an abnormal distribution of

data and forced us to use the Mann Whitney U test and the Wilcoxon Signed Ranks test.

Another contributing factor could have been the design of the experiment because when

the second treatment included only 3 females, so scan sampling included only 3

individuals instead of 6. Controlling for the time of day will help reduce the variables as

well as collecting more data.

Based on this research, more information needs to be gathered regarding female

behavior in different social contexts. The next step would be to collect more data. In

regards to anti-predatory behavior, different aspects besides size need to be explored.

After collecting this preliminary data, the evolutionary and societal implications can begin

to be explored.


Literature Cited

Clark, D. C. and A. J. Moore. 1995. Social Communication in the Madagascar Hissing

Cockroach: features of male courtship and a comparison of courtship and agnostic

hisses. Behavior. 132: 401-417.

Logue, M. D., S. Mishra, D. McCaffrey, D. Ball, and W.H. Cade. 2009. A behavioral

syndrome linking courtship behavior toward males and females predicts reproductive

success from a single mating in the hissing cockroach, Gromphadorhina portentosa.

Behavioral Ecology. 20:781-788.

Varadinova, Z., V. Stejskal, and D. Frynta. 2010. Patterns of aggregation behaviour in six

species of cockroach: compairing two experimental approaches. Entomologia

Experimentalis et Applicata 136: 184–190


Tables and Figures

Behavior Description Letter Code Feeding By the food and eating it FWalking The walking is considered continuous if it stops for no longer than

3 secondsW

Standing Alert Head up, active body, potential antennae movement SA

Climbing Walking on the walls ClStanding Still Not Active

No movement, head down X

Burrowing Head under B

Behavior Description Letter CodeTouching Any contact TCopulation End of abdomen touching CoWalking over Walking over another individual WoHissing Producing a hissing noise H

Table 1: This table depicts each of the selected states and their definitions as well as a letter code. These states were used to describe the behavior of the Madagascar hissing cockroach.

Table 2: This Table depicts the events used to describe the behavior of the Madagascar hissing cockroach during focal sampling. This table includes the event, definition and letter code.


Descriptive Statistics

N Mean Std. Deviation Minimum Maximum

TimeFsame 24 4.29 11.544 0 49

TimeFmix 24 1.54 7.553 0 37

Wilcoxon Signed Ranks Test for F state behavior

Ranks

N Mean Rank Sum of Ranks

TimeFmix - TimeFsame Negative Ranks 4a 2.50 10.00

Positive Ranks 0b .00 .00

Ties 20c

Total 24

a. TimeFmix < TimeFsame

b. TimeFmix > TimeFsame

c. TimeFmix = TimeFsame

Table 3: This table shows the descriptive statistics, ranks and test statistics used for the feeding behavior (F) in the Wilcoxon Signed Ranks Tests for the feeding state behavior.


Test Statisticsb

TimeFmix - TimeFsame

Z -1.826a

Asymp. Sig. (2-tailed) .068

a. Based on positive ranks.

b. Wilcoxon Signed Ranks Test



TimeSAsame 24 92.75 121.808 0 300

TimeSAmix 24 140.93 130.921 0 300

Table 4: This table shows the descriptive statistics, ranks and test statistics used for the Standing Still Active behavior (SA) in the Wilcoxon Signed Ranks Test.


Wilcoxon Signed Ranks Test for SA state behavior

Ranks


TimeSAmix - TimeSAsame

Negative Ranks 6a 8.17 49.00

Positive Ranks 12b 10.17 122.00

Ties 6c

Total 24

a. TimeSAmix < TimeSAsame

b. TimeSAmix > TimeSAsame

c. TimeSAmix = TimeSAsame

Test Statisticsb

TimeSAmix - TimeSAsame

Z -1.591a


a. Based on negative ranks.





TimeSNSame 24 171.79 140.691 0 300

TimeSNmix 24 143.31 140.302 0 300

Wilcoxon Signed Ranks Test for SN state behavior

Ranks


TimeSNmix - TimeSNSame

Negative Ranks 10a 7.50 75.00


Ties 9c

Total 24

a. TimeSNmix < TimeSNSame

b. TimeSNmix > TimeSNSame

c. TimeSNmix = TimeSNSame

Table 5: This table shows the descriptive statistics, ranks and test statistics used for the Standing still Not Active (SN) in the Wilcoxon Signed Ranks Test.


Test Statisticsb

TimeSNmix - TimeSNSame

Z -.855a






TimeWsame 24 24.54 50.918 0 200

TimeWmix 24 6.84 16.057 0 58

Table 6: This table shows the descriptive statistics, ranks and test statistics used for the Walking behavior (W) in the Wilcoxon Signed Ranks Test.


Wilcoxon Signed Ranks Test for W state behavior

Ranks


TimeWmix - TimeWsame Negative Ranks 6a 6.00 36.00


Ties 15c

Total 24

a. TimeWmix < TimeWsame

b. TimeWmix > TimeWsame

c. TimeWmix = TimeWsame

Test Statisticsb

TimeWmix - TimeWsame

Z -1.601a





Group Statistics

Hiss N Mean Std. DeviationStd. Error

Mean

BodyLength 0 19 44.5826 4.18568 .96026

1 5 45.4200 4.98343 2.22866

Mann-Whitney Test: Tests whether there is a size difference between the cockroaches that hiss and the ones that do not hiss to a potential predator

Ranks

Hiss N Mean Rank Sum of Ranks

BodyLength 0 19 12.21 232.00

1 5 13.60 68.00

Total 24

Table 7: This table shows the group statistics, ranks, and test statistics used in the Mann Whitney U test comparing hissing and body length.


Test Statisticsb

BodyLength

Mann-Whitney U 42.000

Wilcoxon W 232.000

Z -.391


Exact Sig. [2*(1-tailed Sig.)]

.731a

a. Not corrected for ties.

b. Grouping Variable: Hiss

Variables Entered/Removedb

ModelVariables Entered

Variables Removed Method

1 BodyLengtha . Enter

a. All requested variables entered.

b. Dependent Variable: LatFlip

Table 8: This table shows the variables, model summary, and ANOVA of the linear regression comparing body length and latency to flip.


Model Summary

Model R R SquareAdjusted R

SquareStd. Error of the Estimate

1 .189a .036 -.008 76.23825

a. Predictors: (Constant), BodyLength

ANOVAb

ModelSum of

Squares df Mean Square F Sig.

1 Regression 4761.001 1 4761.001 .819 .375a

Residual 127869.942 22 5812.270

Total 132630.943 23

a. Predictors: (Constant), BodyLength

b. Dependent Variable: LatFlip


Figure 1: This figure shows the average time spent on each state behavior for both the female and male/female treatments. F stands for feeding, SA for standing not active, SN for standing not active, and W stands for walking. The left lighter column shows the female only treatment and the right mixed columns shows the male/female treatment.


Figure 2: This figure shows the proportion of observations for each state behavior per each treatment. SA annotates the standing active behavior, F is feeding, and SN is standing not active. The speckled column marked same shows the female only treatment and the shaded column shows the male/female treatment.

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