Beneficial (?) fungus in D. pseudoobscura collection

James L. Farmer JLFarmer at
Fri Jan 31 18:42:44 EST 1997

I collected D. pseudoobscura in the Abajo Mountains of Utah last summer.
This fall, I noticed that some bottles contained a fungus and others did
not.  Flies in bottles with fungus are uniformly healthy and vigorous,
reproduce well, and live long.  Many of the bottles without fungus were
quite unhealthy.  The medium is Carolina blue without added yeast.

It appears that the fungus-free, unhealthy stocks can be improved by giving
them boiled yeast paste in a dot on the side of the bottle.  The yeast
disappears quickly in bottles without fungus.  The flies can be observed
feeding on the paste.  In bottles with fungus, the dot does not disappear.
I assume, but do not know, that the flies are eating the fungus in
preference to the yeast.

I have tried to get someone to identify the fungus, but we do not have a
real mycologist at BYU.  It may be a Penicillium of some sort, but perhaps
not one of the common ones.

I would be happy to ship a sample of the fungus to anyone who would like to
look into this further.  I would especially like to send it to someone who
knows a mycologist who does taxonomy.

James L. Farmer
571 WIDB, Brigham Young University
Provo, Utah 84602-5255, USA

801-378-7423 (FAX)
JLFarmer at

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