[Drosophila] initial population and inserts

Mark Thorson via dros%40net.bio.net (by nospam from sonic.net)
Thu Sep 6 21:29:06 EST 2012

Other than wasting flies, is there any
disadvantage to using too many flies to
start a culture?  I had one batch in which
there was so much larval activity that
the whole surface of the medium seemed
to be moving.  I though these cultures
would be the best I ever had, but although
they were very good they weren't the best.
Many larvae must never have made it to
adults.  I don't know that I started these
cultures with any more adults than usual,
but it's gotten me to wonder if there's
an optimal number (disregarding the waste
of flies when using more than optimal).
I'm thinking an overpopulation of larvae
may produce fewer adults.  Is that true?

The vials I bought came with a sheet of
plastic mesh stuck in the medium for the
larvae to climb and pupate on.  I haven't
been using anything like that, because
my culture vessels always have plenty of
space available on the sidewall.  Larvae
seem to be able to move maybe 2 or 3 inches
a minute, so they should have no problem
finding the sidewall when it's time to
pupate.  Does it increase productivity
to provide these climbing structures
in addition to the sidewall?  My culture
vessels are about 2 1/2 inches in diameter
at the bottom, tapering outward to about
4 inches at the top.  They are 5 inches
tall, not counting the air filter and lid.

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