[Drosophila] Re: culture problems

Mark Thorson via dros%40net.bio.net (by nospam from sonic.net)
Tue Sep 4 17:17:59 EST 2012

dr julien colomb wrote:
> The fact that the adults die and not the larvae is peculiar.
> I never had that before, but it reminds me of a story with pesticides.
> In my former labs, we had to change the corn because the one we used was
> not produced anymore. We took bio-cornmeal and flies started to die: the
> corn was not insecticides free... Maybe you have such a problem?

Beginning with my 8/24 batch, I switched to organic
bananas.  Productivity of my cultures seems about
the same, though I've only noticed two examples of
early adult death.  In both cases, the medium
developed a creamy or melted cheese appearance on
top, which I believe indicates bacterial overgrowth.

My suspicions about carbon dioxide accumulation are
in doubt.  I now think the stinging odor is acetic
acid.  It does not seem to be associated with poorly
productive cultures.

I think my earlier suspicions about bacteria being
the main problem might be correct.  I'm thinking
that I need to consider ways to eliminate possible
sources of contamination.  I do wash all of my
equipment with hot water and detergent, but I
had not been doing anything with the disposable
plastic cups I use as culture vessels.  I was
assuming they were sanitary fresh from the package.
I'll start chemical sterilization with hydrogen
peroxide on the cups and see if that has an effect.

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