Another plea for advice flung into the ether:
We're seeing a new problem with our lab stocks:
In some bottles a high proportion of flies will fail to eclose, with many
pupae (and sometimes wandering third instars) dying and turning black.
This phenomenon is not consistent, and a given stock will be affected for
1 or 2 generations, then appear to be fine for 1 or 2 more. It will also
appear first in a few bottles then in the entire tub in a subsequent
generation. Mites are not the problem, nor is there any obvious mold or
fungus. We suspect some infectious agent; Nosema has been mentioned as a
problem on this group recently, but the original poster didn't mention the
pupae blackening, and our adults don't appear to suffer the same early
mortality he described.
This "plague" doesn't happen, at least at a significant level, in vial
stocks, only in lines we've expanded into bottles.
Has anyone out there seen this "black pupae" phenomenon, and if so, how
did you deal with it? I'll be happy to summarize any responses not posted
to the group.
Chris Jones (jonesc at cshl.org)