Drosophila melanogaster

The life cycle of Drosophila melanogaster at 25 °C takes only 2 weeks. Females lay eggs (embryos) that eclose after 24 h. The resulting larvae grow for 5 d while molting twice, at about 24 and 48 h after eclosion, before encapsulating in the puparium and undergoing a five-day-long metamorphosis.

Females first mate about 8 h after emergence. The females store sperm from previous males they mated with for later use. For this reason geneticists must collect the female fly before her first mating, that is, a virgin female, and ensure that she mates only with the particular male needed for the experiment.

Drosophila melanogaster was chosen as a genetic animal model at the beginning of the twentieth century by Nobel Prize winner Thomas Hunt Morgan. Since then it has been a very succesful animal model for biological research, for several reasons:

• It is small and easy to grow in the laboratory.
• It has only 4 chromosomes.
• Males do not show recombination, facilitating genetic studies.
• Genetic transformation techniques have been available since 1987.
• Its compact genome was sequenced in 1998.