What is the Difference Between Male and Female Fruit Flies

The main difference between male and female fruit flies is that male fruit flies are comparatively small in size whereas female fruit flies are around 25% larger than their male counterparts. Furthermore, the abdomen of the male fruit fly is rounded at the bottom while the abdomen of the female fruit fly is pointed at the bottom. Moreover, the last two strips of the abdomen of the male fruit fly are much darker while the female fruit fly has one thicker band at the bottom of the abdomen with a lighter band on top of that.  

Male and female fruit flies are the two gender of the fruit fly (Drosophila melanogaster ). Generally, the species is also known as the common fruit fly or vinegar fly. Significantly, it is a common pest in places where food is reserved. Meanwhile, it is commonly used in research as it can be readily reared in the laboratory. 

Key Areas Covered 

1. Fruit Fly
     – Taxonomy, Characteristics, Importance in Research
2. Male Fruit Flies
     – Distinguishing Characteristics
3. Female Fruit Flies
     – Distinguishing Characteristics
4. What are the Similarities Between Male and Female Fruit Flies
     – Outline of Common Features
5. What is the Difference Between Male and Female Fruit Flies
     – Comparison of Key Differences  

Key Terms 

Abdomen, Chromosomes, Dark Strips, Diptera, Female Fruit Fly, Fruit Fly, Male Fruit Fly

Fruit Fly – Taxonomy, Characteristics, Importance in Research 

Fruit fly (Drosophila melanogaster ) is a species of fly that belongs to the family  Drosophilidae. The other names for the species include the common fruit fly and vinegar fly.  

Physical Appearance 

Generally, the wild type of fruit fly has a yellow-brown color. The average size of it is 3 mm in length including wings and 2 mm in width. Also, they have a segmented body into head, thorax, and abdomen. Significantly, the transverse black rings in the abdomen are the main distinguishing feature of male and female fruit flies. In addition to these, fruit flies are hexapod insects with typically three pairs of legs in the thorax. 

Figure 1: Fruit Fly

Moreover, these flies walk using the tripod gait in which three of the legs swing together while the other three remain stationary or instance. Besides, the fruit flies belong to the order Diptera, the order of true flies having two wings. They also have five large, brick-red eyes and antennae. Also, the proboscis is the feeding organ of a general fly and it is used for both taste cue detection and food ingestion. Importantly, the natural habitat of fruit flies is rotting fruits. 

Life Cycle and Reproduction 

Fruit flies undergo complete metamorphosis with four stages in their life cycle; eggs, larva, pupa, and adult. The lifespan of it under optimal growth conditions at 25 °C is about 50 days. Furthermore, their development depends on the temperature as in many endothermic species. That is; the development time increases in higher temperatures due to the heat stress. Besides, it increases under crowded conditions although the emerging flies are smaller. 

Figure 2: Fruit Fly Life Cycle

Moreover, female fruit fly lies around 400 eggs about 5 at a time into either rotting fruit or decaying mushrooms and sap fluxes. The eggs, which hatch after 12-15 hours are about 0.5 mm long. Also, the resulting larvae grow for about four days and molt twice. They consume microorganisms on the decomposing material. Usually, the encapsulated larvae in the puparium undergo four days-long complete metamorphosis. Besides these, both male and female fruit flies undergo polygamy in which they have multiple sex partners at the same time. Importantly, this increases the genetic diversity of the offspring as an evolutionary advantage, increasing the fitness to the environment. 

Genetics 

Typically, the genome of a fruit fly contains four homologous pairs of chromosomes: two pairs of large autosomes, one pair of very small autosomes, and a pair of sex chromosomes. Also, females normally have two X chromosomes (XX), while males have one X and one tiny Y chromosome (XY). Importantly, flies with a single X chromosome (XO) are sterile males. Basically, fully-described chromosomes in terms of their easily visible banding patterns make a fruit fly an excellent subject for the study of chromosome structure and function, and of gene action and its control.

Figure 3: Fruit Fly Chromosomes

Interestingly, the fruit fly is among the first organisms used for genetic analysis. Thomas Hunt Morgan was the preeminent biologist studying fruit fly early in the 1900s.  He elucidated many basic principles of heredity, including sex-linked inheritance, epistasis, multiple alleles, and gene mapping. Today, it is one of the genetically best-known of all eukaryotic organisms. Therefore, the fruit fly model is important for understanding comprehending processes such as transcription and replication in other eukaryotes, including humans.

Figure 4: Fruit Fly Genetic Linkage Map

The size of the fruit fly genome is around 139.5 million base pairs, containing 15,682 genes. In comparison, 60% of genes are conserved between the fruit fly and human genomes. Also, about 75% of known human disease genes have a recognizable match in the genome of fruit flies. On that account, the fruit fly is used as a genetic model of human diseases, including the neurodegenerative disorders; Parkinson’s, Huntington’s, spinocerebellar ataxia and Alzheimer’s disease. Also, it is important in the study of mechanisms underlying ageing and oxidative stress, immunity, diabetes, and cancer, as well as drug abuse.  

Importance in Research 

The fruit fly is a popular choice as a model organism due to many reasons. Basically, in rich cultures at 25 °C, it can complete its life cycle within two weeks. Also, a single female can lay several hundreds of eggs at a time. Moreover, a considerable number of flies can raise in a confined space as they are small. Above all, they are large enough to recognize the morphological and behavioral characteristics as well as mutants. In addition to these, biochemical differences can be identified in a single fly as well.  

Male Fruit Flies – Distinguishing Characteristics 

Male fruit flies are the slightly smaller of the fruit flies. Also, a significant feature of them is the distinct dark patch at the bottom. Generally, each segment of the abdomen of the fruit fly contains a dark band. Here, the last two bands at the bottom are meld together to form this distinctive dark patch at the bottom. However, the abdomen of the male fruit fly is shorter in contrast to that of the female fruit fly. Therefore, the male fly has fewer bands on its abdomen.

Figure 5: Female and Male Fruit Fly

Moreover, the sex comb is another minute distinguishing feature of the male fruit fly. Usually, it is a short row of thick, closely spaced bristles appearing as a dark mass on the fourth segment of the front legs (often seen best with fly lying on its back). Basically, sex comb is important for grasping female’s abdomen and genitalia and to spread their wings prior to copulation. 

Female Fruit Flies – Distinguishing Characteristics 

Female fruit flies are the larger counterpart of the fruit flies. Thus, they have a comparatively, longer abdomen. On that account, their abdomen contains a higher number of dark strips. Also, their topmost bands are thicker while the bands at the bottom are lighter. Also, the bottom of the female abdomen is pointed towards the bottom.  

Similarities Between Male and Female Fruit Flies  

• Male and female fruit flies are the two gender of the fruit fly (Drosophila melanogaster).  
• Also, it is a common pest in places where food is reserved as its natural habitat is the rotting fruit.  
• Besides, it is commonly used in research as it can be readily reared in the laboratory. 

Difference Between Male and Female Fruit Flies

Definition 

Male fruit flies refer to the smaller fruit flies with one X chromosome and one tiny Y chromosomes as sex chromosomes while female fruit flies refer to the larger fruit flies with two X chromosomes as sex chromosomes. 

Body Size 

Male fruit flies are smaller while female fruit flies are 25% larger than their male counterparts. 

The Shape of the Bottom of the Abdomen 

The abdomen of the male fruit fly is rounded at the bottom while the abdomen of the female fruit fly is pointed towards the bottom.  

Presence of ‘Spike’ 

Male fruit flies do not have a ‘spike’ while female fruit flies have a ‘spike’ on the dorsal surface at the rear. 

Banding Pattern in the Abdomen 

Male fruit flies have fewer strips of which the last two strips are meld together, becoming much darker towards the back of the abdomen while the female fruit flies have more strips of which one thicker band at the bottom of the abdomen with a lighter band on top of that.  

Sex Comb 

Male fruit flies have sex comb, a short raw of thick, closely spaced bristles on the fourth segments of the front legs while female fruit flies do not have a sex comb. 

Choosing Mating Partners 

Male fruit flies dance and brush against the female’s body while female fruit flies choose a mate within 15 minutes. 

Conclusion 

Male fruit flies are the smaller flies between the two genders of the common fruit fly. Apart from the size, the banding pattern of the abdomen is the main characteristic feature that distinguishes them. That means; the abdomen of the male fruit flies contain fewer black strips and the last two strips at the bottom of the abdomen meld together to form a darker area. In addition to this observable difference, the bottom of the abdomen of male fruit flies is rounded and the forelegs of them contain a sex comb. Meanwhile, female fruit flies do not have a sex comb. Also, their abdomen is pointed towards the bottom and contains more black strips with a thicker strip at the bottom.In brief, the main difference between male and female fruit flies is their body size, the shape of the abdomen, and its banding pattern. 

References:

1. “An Introduction to Fruit Flies.” The Berg Lab, University of Washington, 11 July 2017, Available Here.
2. “The Fly Manual – A Guide to Working with Drosophila.” LiveGene, Tauber Lab. Available Here.
3. Gilbert SF. Developmental Biology. 6th edition. Sunderland (MA): Sinauer Associates; 2000. Chromosomal Sex Determination in Drosophila. Available Here.
4. Reuven Dukas, Carling M. Baxter, Mate choosiness in young male fruit flies, Behavioral Ecology, Volume 25, Issue 3, May-June 2014, Pages 549–552, Available Here.

Image Courtesy:

1. “Drosophila melanogaster Proboscis” By Sanjay Acharya – Own work (CC BY-SA 4.0) via Commons Wikimedia   
2. “03 Drosophila melanogaster Life Cycle” By Image Editor (CC BY 2.0) via Flickr
3. “Drosophila-chromosome-diagram” By Steven J. Baskauf – I created this diagram. (Public Domain) via Commons Wikimedia   
4. “Drosophila Gene Linkage Map” By Twaanders17 – Own work (CC BY-SA 4.0) via Commons Wikimedia    
5. “Biology Illustration Animals Insects Drosophila melanogaster” By Madboy74 – Own work (CC0) via Commons Wikimedia