Drosophila melanogaster

Drosophila melanogaster, which is commonly known as fruit fly and comes under the family Diptera.

It is mostly seen in all regions, where it flies above the fruits and undergoes its life cycle mostly in ripened fruits such as banana.

This is mostly used as a specimen in biology to undergo a study or research in its lifecycle.

It is also used in the field of genetics, pathology and microbiology for research purposes.

Drosophila melanogaster is most commonly used in the field of research as it has a shorter life span and also consisting of only four pairs of chromosomes, and it produces a greater number of off springs in a quitter period of time.

It is known as the African species having all the non-African lineages.

More than a research specimen it is generally a common pest or insect in restaurant, home and in road side food stalls.

Scientific Classification of Drosophila melanogaster

Kingdom : Animalia

Phylum : Arthropoda

Class : Insecta

Order : Diptera

Family : Drosophilidae

Genus : Drosophila

Species : D. melanogaster

Physical Characteristics of Drosophila melanogaster

Drosophila melanogaster is considered as a wild type of flies, and they are usually colored with yellow and brown along with black transverse rings in the region of their abdomen.

The eyes are brick red in color. And this color is due to the presence of pigments xanthommatin.

These flies have their sexual dimorphism such that females have their backs longer than males.

Males have dark rounded short backs. However, they are easily distinguished; as males have their abdomen darker than females and they also contain spiky hair around their reproductive regions.

These flies are also capable of sensing air currents which makes their hair move along the air currents and as well their eyes are also sensitive to intense light, so that they are away from predators when a shadow falls on them.

Life Cycle of Drosophila melanogaster

Generally, these flies have a growth range of about 50 days from the stage of egg to death.

However, the development depends upon the temperature, humidity and other notable factors.

Considering the shortest growth rate i.e., from egg to adult it is of 7 days, and the temperature noted here is of 28ºC.

Under increased temperature and at crowded areas the development of these flies increases but it results in smaller flies.

Life cycle of Drosophila melanogaster with stages is shown below

Where as Drosophila melanogaster is an holometabolous insect, which means that it has the capability to undergo full metamorphosis.

The life cycle of Drosophila melanogaster is divided into four stages as embryo/ egg, larva, pupa and adult.

The eggs hatch after half a day that is from 12 to 15 hours of laying which are about 0.5 mm in its size.

The larva which comes out of the embryo has its duration of about 4 days, during this larval stage mounting undergoes twice which results in instars as second and third instar.

During these stages they feed on decomposed matter such as decayed mushrooms, microorganisms and in fruits and enters through the pupal stage where it undergoes metamorphosis for 4 days at 25º C and after this stage come the adult fly.

Reproduction in Drosophila melanogaster

Males Drosophila melanogaster perform a behavioral pattern to attract female Drosophila melanogaster, where males place themselves extending their wings horizontally and starts singing a courtship song by vibrating their wings, then male make their position beyond the female’s abdomen and undergoes copulation.

If females are not interested, they kick the males out.

During copulation males transfer their hundreds of long sperm cells into females, then females store their sperm cells in the seminal vesicle which is present between spermathecae.

Sperm cells compete and undergoes fertilization, then it is being followed by fertilization after several copulation processes.

Female lays about five eggs at a time and almost 400 eggs in its lifetime.

The female mates with first mater throughout its life as it has its sensory neurons in their uterus; which responds to it, by sending signals to the hypothalamus.

Why Drosophila melanogaster is a Model Organism in Genetics?

Drosophila melanogaster is the most commonly used specimen in the life study of genetics and has its own importance in the field of developmental biology too.

It is used to study the environmental mutagenesis.

These were considered as the first organism to use in research field as fruit flies help in the better understanding of transcription and replication in all living eukaryotes inclusive of humans.

Thomas Hunt Morgan, who was the first researcher to use fruit fly in his hereditary experiments, at Columbia University in a Fly room, where the scholars used milk bottle to capture the flies and rear them and as well, they started observing their traits in a microscope which results in better observations.

Only through this study Morgan and his colleagues found out the basic theories and principles of heredity such as gene mapping, epistasis, multiple alleles and sex-linked inheritance.

They are being used since the historical period to study the patterns of inheritance and to know about mutagenesis particularly about environmental mutagenesis.

There are several valuable reasons why we use these flies in laboratory and few of them are:

There is no need for any large culture mediums or equipment’s to carry out experiments with them.

It can also be anesthetized just by giving ether or carbon dioxide as it does not require any medications or vaccines.

Its morphology can be read easily in anaesthetized flies.

Since it has a short life span it helps us to read the mutations and hereditary variations that it undergoes genetically for generations.

It has also had the capability to produce more individuals at a short period of time.

It can also be cultured easily without spending any funds against it.

Females can also be identified easily as, virgin or not and thus helps in experimenting cross genetic techniques.

Where as the mature larva contains a giant chromosome in their salivary glands which is also known as polytene chromosomes.

It also has a puff like structure in the center which helps us to identify the region where transcription takes place.

These flies show its developmental period in a shorter sequence of time. So, it is very helpful in reading developmental biology.