[Drosophila] Re: drosophila cultures dying

[Chris Jones]

In article <mailman.530.1166650814.19683.dros At net.bio.net>,
 The Hanings <haningfamily At yahoo.com> wrote:

> Hello.  My daughter is working with D. melanogaster
> for the third year for a science fair project. 
> Beginning about 4 to 6 weeks ago about half of the new
> cultures we made die within a few days.  We are using
> a commercial media from Conn Valley Biological Supply.
>  The affected cultures have a tan colored, mucoid
> substance on the surface of the media.  They also have
> a terrible odor.  The media has mold inhibitors so we
> suspect a bacterial contaminant.  We submitted
> cultures for bacterial identification, but the results
> are not in yet. Any thoughts on what might cause this
> die off?

Almost certainly bacterial, from your description. You might try more 
frequent flips, so there's less of an initial bacterial load, giving the 
relatively few larvae a better chance, but I'd toss in some antibiotics 
for a generation and see if that clears up the problem.

I don't know how things are in your part of the world, but I gave up on 
Carolina medium when I worked in Nashville -- too many mold spores in 
the air, so I'd routinely end up losing 1/3 to 1/2 of my vials to mold. 
Whether their mold inhibitors were dead, inadequately mixed in, or just 
inadequate I don't know, but I switched to cooking my own food and 
haven't had a problem since. Impractical if your daughter's doing her 
project at home, but I thought I'd mention it.

Chris Jones