Lab report :The Effect of Male Fertility on the Amount of Eggs produced in Female Bean Beetles.

Lab report :The Effect of Male Fertility on the Amount of Eggs produced in Female Bean Beetles.

Abstract

The main goal of this investigation was to find out whether mating of a virgin male to a virgin female produces more eggs than virgin females who copulated with non-virgin males. This study hypothesizes that beetles who are virgin copulating with other female virgins makes produces more eggs than female beetles who have to copulate with non-virgin males. Males who are non-virgin are assumed to cause less egg production by virgin female beetles. The study predicts that if we mating of both male and female virgin beetles will lay more eggs than the copulation of males who are non-virgin with females never copulated before. The research involves groups of virgin female and male beetles or non-virgin males and virgin females and documented the amount of eggs per bean (n= 20 females per treatment). The outcome variable in this study was the volume of eggs produced by virgin females. In contrast, the predictor variable was the virginity status of a male beetle (virgin or non-virgin). T-test was the chief statistical instrument used in this study. Independent sample t-test was the main test utilized in this study because we needed to relate the effect of virgin male beetles and non-virgin male beetles on virgin female eggs production. The study found that there was not a substantial variation in the average Quantity of eggs by virgin females mated with virgin males against those mated with non-virgin males. This meant that male fertility does not play a substantial consequence on the quantity of offspring given by feminine beetles. The decrease in the amount of sperm size in males did not play a factor in the Amount of eggs. The average number of eggs was more than that of females who mated with virgin male (average=41.5) than female beetles who copulated by non-virgin male (average=27.9). It concluded that there existed no significant difference in averages of amounts of eggs produced virgin females between virgin male beetles and non-virgin male beetles and recommended further studies to use larger sample sizes.

Introduction

Bean beetle insect which is also referred to as Callosobruchus maculatus or cowpea seed beetles from South East Asia and Africa regions (Beck and Blumer,2019).  They generally recognized as “pest insects,” and they lay their eggs on the bean’s surfaces.  They seem to be compressed and has an oval body shape, with brown and black colors (Beck and Blumer, 2019).  The male Cowpea seed beetles only live to about 7-14 days, where throughout this period, mating and oviposition takes place (Beck and Blumer, 2019).  After mating and oviposition process, female beetles place their eggs, also known larvae on beans surfaces, which they find to be suitable and with adequate food (Beck et al., 2016). As the age of larvae increases, and it continues to grow, the mother chews the bean letting the offspring eat and continue surviving.  Since the offspring of the Beetle depends only on the bean plant, it is the responsibility of the female Beetle to find for the best plant that will allow the larvae to survive (Rova and Björklund,2011).  This now leads to a female Bean Beetle choose the been to dwell on. Even though there exist several beans that a female beetle can choose, it has to be careful in selection because there live a few species that support the development of larvae.  Some of the species are toxic and dangerous to the offspring (Beck and Blumer, 2019). When the female Beetle and offspring feel that their lives are at danger, they drop from the bean plant (Beck and Blumer, 2019).

Both non-virgin and virgin male and female beetles mate. Male beetles who are virgin, on the other hand, may not yield completely formed spermatophores until one day after emergence.  Again, female beetles may take several hours after mating to mate again. It is believed that virgin male Beetle produces large amounts of sperm than non-virgin, and this could make virgin females produce more eggs. In this study, we want to find out whether virgin womanly beetles  who mates to virgin males  produces more eggs than female beetles who virgin and  copulated with non-virgin males.

This study hypothesizes that virgin males beetle makes virgin females produce more eggs because the male’s sperm size decreased yet. The non-virgin male beetles are assumed to cause a less egg production by virgin female beetles. The study predicts that if we mate a virgin male and virgin female, then they will lay more eggs than non-virgin males and virgin females.

Method

To determine how the fertility of the males affects the quantity of eggs female beetles produce, we likened the Sum of eggs laid by virgin feminine beetles who mated with non-virgin or virgin males.  To do this, we set up groups of male beetles who are virgins as well as virgin female beetles or  masculine beetles who have copulated and virgin feminine beetles and documented the Sum of eggs per bean (n= 20 females per treatment). We recorded fruitful mating at 5 minutes of mounting. After mating the bean beetles, the females were put in an individual petri dish then positioned it in an incubator for seven days to ensure she can lay as many eggs as possible. All petri dish was stored in the same incubator to account for temperature and light levels playing a factor on the Amount of eggs laid. To ensure every female had enough space, 30 black eye beans were positioned in each petri dish sideways with the female beetle. A concern that arose is we could not estimate how many times non-virgin beetles have mated, only that they have mated, thus classifying as non-virgin. Non-virgin beetles could have mated once, twice, or even more.

The materials used in this study were; 20 of each Beetle (virgin male, non-virgin male), 40 virgin females, 40 Petri dishes, 1200 black eye beans (30 beans for each petri dish), and forceps and a microscope. The above materials facilitated the collection of relevant data for the study.

The study variables were categorized into four categories; dependent variables, control, confounding and independent variables.   The dependent variable is the outcome of the investigation, and in this study, the dependent variable was the Amount of eggs. Control variables were; Temperature , Bean type (black eye beans), Light level, Amount of beans (30) Large petri dish. Confounding variables in this study involved age, Number of times they mated, and Willingness. The Independent variable is the one set by the experimenter, and in this investigation, we set virginity of male bean beetle as the independent variable.

Independent sample t-test was the prime statistical assessment used in this research because we want to relate the effect of virgin male beetles and non-virgin male beetles on virgin female egg production. The test was to find out whether there is a substantial difference in the average quantity of eggs yielded between females mated with male beetles who never mated and females who bred with males who are virgin.

Results

The main goal of this study was to explore how virginity of the male beetles affects the Number of eggs females bean beetles produce. This section gives summary statistics, graphical representation of the mean of eggs produced by female beetles copulated with virgin beetles and non-virgin male beetles, and finally t-test to show whether there exists a significant difference in averages of eggs produced by virgin beetles between virgin and non-virgin beetles.

From table 1 below, virgins females copulated with virgin male beetles had produced an average of 41.5 eggs (Standard Deviation =27.869). Virgin female beetles bred with non-virgin male beetles produced an average of 27.9 eggs (Standard Deviation = 27.728). The mean of Quantity of eggs by female beetles is also illustrated in figure 1 below.

Table 1:

Summary statistics for the Sum of eggs produced by virgin female beetles who copulated with virgin males against those mated with  non-virgins.Figure 1: means of quantity of eggs produced by virgin females who copulated with two categories male beetles .

There exists insignificant difference in the average quantity of eggs produced by female beetles who a virgin and copulated virgin males against females who mated non-virgin beetles (unpaired t-test, t stat=1.547, 38 df, p=0.1301). This means that male fertility does not play a factor in the Amount of eggs yielded by feminine beetles. The decrease in sperm size in males did not play a factor in the Quantity of eggs. The average number of eggs was higher, with females who copulated with virgin male beetles (Average=41.5) than female beetles who copulated with non-virgin males(Average=27.9). However, that does not cause a difference enough to be significant.

Table 2:

Unpaired T-test results

Discussion

After analysis, the study revealed that mating virgin male beetles with virgin females do not increase the Amount of eggs. The study found that there existed no significant difference in averages of amounts of eggs produced virgin feminine beetles between non-virgin males and virgin males (t stat=1.547, p=0.1301). This is contrary to the hypothesis of this study that mating virgin male and virgin females produce more eggs than mating of males who are non-virgin with females never copulated before. Virginity status of male Beetle does not have a noteworthy consequence on the Amount of eggs in which a virgin feminine beetles produced. Since the production of eggs may also be affected by the female Beetle, this could have affected our projections. Despite virgin male Beetle producing enormous Amounts of sperms than non-virgin males, the Amount of eggs will depend on the fertility of the female Beetle. Again, these Beetles are found across Asia and Africa with different climatic conditions, and bean species. The number of eggs depends on nutrients these beetles receive from bean plants, and our findings may have been affected by the use of similar bean type. The same bean will give related nutrients to female beetles hence produce the same amount of eggs.

The finding of this study is not consistent with the study hypothesis. Some other reasons that may have affected our study are sample size. The study used a sample size of 20 pairs, which is significantly small(Rupp and Pant,2007). We recommend further research to use a large sample size. A larger sample size increases the reliability and validity of the data.

References

Beck C. W., Blumer L.S, and Habib J. (2016). “Effects of Evolutionary History  on Adaptation in Bean Beetles, a Model System for Inquiry-based Laboratories.” Evolution: Education and Outreach Evol Educ Outreach 6.1 (2013): 5. Springer Open.

Beck, C.W., & Blumer L. S (2019). A Handbook on Bean Beetles, Callosobruchus maculatus: Developing Bean Beetles as a Model System for Undergraduate Laboratories.

Rova E and Björklund M (2011) Can Preference for Oviposition Sites Initiate Reproductive Isolation in Callosobruchus maculatus? PLoS ONE 6(1): e14628.

Rupp, A. A., and Pant, H. A. (2007), “Validity theory,” in Salkind, Neil J. (ed.), Encyclopedia of Measurement and Statistics, SAGE Publishing.