Drosophila, like other animals, requires an optimum temperature for its survival,
growth, and breeding (20°–25°C). The temperature around and above 31°C
makes the flies sterile and reduces the oviposition; it may also result in death.
At lower temperatures, the life cycle is prolonged and the viability may be
The routinely used food media for the maintenance of Drosophila is “cream
of wheat agar” medium.
The ingredients of this media for preparing culture bottles are as follows:
- Distilled water – 1000 mL
- Wheat flour (rava) – 100 gm
- Jaggery – 100 gm
- Agar agar – 10 gm
- Propionic acid – 7.5 mL
- Yeast granules.
Wheat flour and jaggery are boiled in distilled water until a paste is formed.
To that, agar agar and yeast granules are added after cooling. Propionic acid
is added to avoid fungal infection of the medium.
Heat-sterilized bottles should be used for preparing cultures. Similarly, sterilized
cotton has to be used to plug the bottles. As the condition of the medium
deteriorates with time, the flies have to be transferred from the old to new culture medium at least once in 3 weeks.
Whenever the flies have to be analyzed, either for routine observations or
for experiments, they have to be anaesthetized to make them inactive. The
procedure is to transfer the flies from the media bottle to another empty widemouthed
bottle, referred to as an etherizer. The mouth of this bottle is covered
with a stopper and sprayed with ether. It takes about a minute to anaesthetize
the flies. After this, the flies are transferred to a glass plate for observation
under a stereo zoom microscope. If the etherized flies revive before the
completion of the observation, they have to be re-etherized using a re-etherizer
(ether-soaked filter paper fitted in a petriplate, which has to be placed over
the flies on the glass plate). The overetherized flies will have their wings and
legs extended at right angles to the body, and such flies are considered to be
The flies should be handled with a fine painting brush. In the process of
handling the flies, care should be taken not to damage them. The flies should
be discarded after observation.