Effect of High Carbohydrate Diet on the Growth and Reproduction of Drosophila Melanogaster

Effect of high carbohydrate diet on the growth and reproduction of Drosophila melanogaster species

Annette Massihi and Arpi Azarian

Department of Biological Science

SaddleBack College

Mission Viejo, CA 92692

Abstract

The project focuses on the effect of high carbohydrate diet on the reproduction/survival rate of Drosophila melanogaster. Hypothesis tested is that fruit flies with regular diet have greater reproduction and survival rate. For conducting the experimetn 360 wingless fruit flies were divided into two groups of 180 where the first group had high carbohydrates (with maple syrup) and the other group had regular nutrient diet. For four weeks each group was kept in nine different vials of 20 (10 males and 10 females). Light microscope was used for data collection. Through statistical analysis a comparison of larva, pupa and adult rate was conducted. The average rates of regular diet group for larva, pupa and adult production for the first generation was (130±126, 81±77, 67±64), and (112±108, 69±65, 47±44) for high carb diet. For the second generation the values were (161±158, 96±92, 80±76) for regular food diet, and (101±98, 45±41, 26±23) for high-carb diet. The result showed that the reproduction and development rate of the group with regular diet had higher rate of survivals in different life stages compared to the group with high carbohydrate diet.

Introduction

Development and reaching to sexual maturation to reproduce is most crucial aspect of an animal life that is directly connected to nutrition and growth. A comparison of the lifespan and egg production showed that longevity is commonly expected to trade off beside reproductive effort and a low carbohydrate and protein diet results in lower longitivity and higher egg reproduction (Lee et al., 2008). Carbohydrates are energy source for many important reactions in live organisms and a low carbohydrate intake restricts an organism’s available energy and slows down growth and regeneration, thereby altering survival and health (Lushchak et al., 2014).

Based on the recent demographic experiments moderate nutrient manipulation in adult Drosophila affects mortality rate in a reversible manner, which suggests that dietary restriction in Drosophila increases lifespan through a reduction of the risk of death rather than a slowing of aging-related damage (Pletcher et al., 2005). Moreover, sucrose that is commonly used in recipes of Drosophila laboratory food as a source of carbohydrate may shorten life span and lower egg-laying capability on the diets with very low protein content and high in carbohydrates (Lushchak et al., 2014). Adverse effects of high sucrose diet on fly development and viability may concern control of fly metamorphosis mediated by insulin signaling. (Rovenko et al.,2015). Lifespan extension by dietary restriction should not be thought of as a simple trade-off with fecundity even though such extension is often accompanied by fecundity reduction and even though such manifestation of longevity vs. reproduction trade-off is to be expected from the evolutionary standpoint (Dick et al., 2011).

The hypothesis being tested states that fruit files with regular food diet will have greater reproduction and survival rate in different life stages compare to the fruit flies with high carbohydrate food diet.

Materials and Methods

The research project was performed over a period of four weeks. A total of 360 Drosophila melanogaster fruit flies were divided into two groups of 180 with different dietary nutrients. One group had nutrients that contain high level of carbohydrate, which was made by adding organic maple syrup to the flies’ usual food source. The other group had regular nutrients without maple syrup. Each group was kept in nine different vials of 20 (10 males and 10 females) to avoid crowdedness and facilitate random mating.

Specified dietary nutrients were provided to every group and then waited for the adult Drosophila to lay egg. Yeast paste was used in each fruit fly vial to induce their reproduction and egg laying ability. Usually, it took about 3-4 days for the adult Drosophila to lay eggs and 7-10 days for the eggs to become adults. A microscope was used for counting the larva, pupa and adults of the fruit flies, and fly nap was used to inactivate the new generation of fruit flies for a short period of time in order to count them by placing the flies on pitri dishes. In addition, water soap was used to kill the old generation. Once the old generation laid eggs; thereafter, the old generation was killed and the new generation’s larva, pupa and adults were counted to see how high carbohydrate nutrient environment has affected on the fruit flies survival and reproduction rate. The data were put on Microsoft Excel and the differences in the survival and reproduction rate between the groups with regular and high carb diet were observed. Using statistical tools such as such as stat plus, an unpaired one-tail t-test was done for both groups based on the collected data. This was done to see if there was a significant difference between the survival and reproduction rate of fruit flies with regular nutrient and high carb nutrient.

Results

The results of this experiment were gained during the four weeks of experiment for two generations of the fruit flies with two different flies. For each generation the number of Larva, pupa and Adult was counted for both groups. The data from the first generation of flies with high carb food is demonstrated in Table 1a and the data from the first generation of flies with regular food is demonstrated in Table 2b. Table 2a and Table 2b demonstrate the results gained from the second generation for two diet groups.

Vials / Larva / Pupa / Adult
1 / 130 / 66 / 48
2 / 90 / 45 / 35
3 / 88 / 70 / 28
4 / 96 / 58 / 34
5 / 118 / 73 / 52
6 / 108 / 45 / 33
7 / 100 / 90 / 73
8 / 135 / 69 / 45
9 / 129 / 89 / 66
Vials / Larva / Pupa / Adult
1 / 101 / 80 / 72
2 / 168 / 74 / 61
3 / 128 / 67 / 65
4 / 80 / 45 / 38
5 / 113 / 89 / 59
6 / 148 / 88 / 76
7 / 99 / 95 / 80
8 / 179 / 90 / 77
9 / 139 / 85 / 65
Vials / Larva / Pupa / Adult
1 / 169 / 80 / 70
2 / 110 / 76 / 66
3 / 148 / 66 / 50
4 / 190 / 99 / 83
5 / 105 / 89 / 78
6 / 200 / 105 / 90
7 / 140 / 95 / 80
8 / 138 / 101 / 88
9 / 240 / 139 / 100
Vials / Larva / Pupa / Adult
1 / 70 / 30 / 16
2 / 93 / 34 / 21
3 / 75 / 66 / 32
4 / 63 / 52 / 26
5 / 129 / 45 / 23
6 / 99 / 43 / 30
7 / 134 / 40 / 31
8 / 107 / 34 / 22
9 / 127 / 42 / 18

Statistical analysis was used for calculating the results of the experiment. The figure below (Figure 1) displays the average larva, pupa and adult generation numbers for the flies on regular and high carbohydrate food diet for the first generation. The production rate was higher for the group on the regular food diet than the group on high carbohydrate diet. The rate production for larva, pupa and adult for regular food diet was ((130±126, 81±77, 67±64 ± SEM, N=180) on average respectably and it was (112±108, 69±65, 47±44) ± SEM, N=180) on average respectably for the group on high carbohydrate diet.

Figure 1:illustrates the average rate production for the life stages (larva, pupa and adult) of the fruitless of the first generation with regular and high carbohydrate diet. (pLarva=0.0876, pPupa=0.0641, pAdult = 0.0041 one tailed unpaired t-test)

The results from the second generation are shown in (Figure 2). On average the rate production was higher for the group on the regular food diet than the group on high carbohydrate diet. The rate production average for larva, pupa and adult for regular food diet was (161±158, 96±92, 80±76 ± SEM, N=180) respectably and it was (101±98, 45±41, 26±23) ± SEM, N=180) respectably for the group on high carbohydrate diet.

Figure 2:illustrates the average rate production for the life stages (larva, pupa and adult) of the fruitless of the second generation with regular and high carbohydrate diet. (pLarva=0.00145, pPupa=3.53*10-6, pAdult = 1.03*10-08 one tailed unpaired t-test)

Discussion:

The average reproduction and survival rate of the fruit flies that had regular food source was higher in different life stages (larva, pupa and adults) compared to the fruit flies that had high carb sugar nutrients. The average rate of reproduction of the 2nd generation is even lower than the first generation for the flies that had high carb nutrient. Upon further scrutiny and running the one tail unpaired t-test with all p value for the first and second generations were less than 0.05, which confirms there is a statistically significant difference in the average reproduction and survival rate of the two subject fruit flies.

Thus, it can be concluded that the results support the hypothesis that fruit files with regular food diet have greater reproduction and survival rate in different life stages compared to the fruit flies with high carbohydrate food diet. As the Carbohydrate to protein ratio decreases and protein becomes more available in a diet, reproduction is activated and much of carbohydrate energy is diverted from somatic maintenance to fuel demand of reproduction and building lipid reservation in eggs. (Fanson et al., 2009).

Based on the recent studies with Drosophila melanogaster species, as the dietary yeast to sugar ratios decreases, the life span of the fruit flies increases. (Fanson et al., 2012).

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