I culture D. melanogaster and D. funebris as the base diet for my frogs using the following medium:
1 cup ReadyBrek
1/3 cup dried potato flakes (not powder or granules)
1/2 tsp sugar
1/2 tsp dried yeast
Enough orange juice to make the medium moist but not sopping wet (a little dry
medium at the bottom is good as the medium becomes more liquid with time).
Incubate 8-24 hours to allow the yeast to start going, then add a folded paper towel for the flies to climb on and AT LEAST 50-100 flies in order to keep the medium churned and prevent excessive bacterial colonization.
The differences between the two species are:
- D. melanogaster: Optimum temperature 20-25°C, cycle time (at optimum temperature) 7 days.
- D. funebris: Optimum temperature 25-30°C, cycle time (at optimum temperature) 14 days. Male D. funebris take about a week after emerging to become sexually mature. This probably prevents mating between siblings in the wild. Because the females are quicker to mature, if you start a culture with all newly hatched flies, the females may not be able to lay fertile eggs. The solution is to use older flies (+7 days) rather than the first big hatch from a culture to start a new brood.
Mites:
There are hundreds if not thousands of species of mite which can infest Drosophila cultures. Some just compete with the flies for food, others are directly
harmful to the flies. Either way, they reduce fly production and you don't
want
them! So:
- Always dust files and sift in a sieve to knock off mites before starting new cultures.
- Don't keep any culture longer than 4 weeks (5 weeks for D. funebris).
- Inspect cultures for mites regularly and trash any infested cultures - zero tolerance for mites!
Without doubt the most comprehensive and useful book on this subject. Think
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