From owner-drosophila@net.bio.net Mon Oct 30 22:00:00 1995
Path: biosci!bcm.tmc.edu!news.msfc.nasa.gov!newsfeed.internetmci.com!tank.news.pipex.net!pipex!lyra.csx.cam.ac.uk!mole.bio.cam.ac.uk!atc12
From: atc12@mole.bio.cam.ac.uk (Adelaide T C Carpenter (Genetics))
Newsgroups: bionet.drosophila
Subject: Re: drosophila disease ?
Date: 31 Oct 1995 20:41:02 GMT
Organization: U. of Cambridge, England
Lines: 20
Message-ID: <4761ku$b5@lyra.csx.cam.ac.uk>
References: <47317a$phj@vishnu.jussieu.fr>
NNTP-Posting-Host: mole.bio.cam.ac.uk

In article <47317a$phj@vishnu.jussieu.fr> poinsot@ccr.jussieu.fr writes:
>We have been breeding Drosophila for years on standard medium (corn meal, 
>agar, dry yeast and nipagine). But now adults die and fist instar larva 
>do not enter the medium but stay on the surface and climb on the walls of 
>the vials. No bacterial or fungic contamination, nor mite were detected.
>Can you help us please? we are loosing our strains! 
>Thank you in advance.

This is exactly the phenotype of food that istoo acid (has too
low a pH).  In my experience (while at UCSD) the culprit was the
dry yeast;  commercial dry Sacchyromyces is for some reason acidic,
and some batches are more so than others.  We solved that problem
then by switching to dry Torrula (another yeast), which is not
acidic;  the flies loved it -- and it was even less expensive!

Adelaide
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