X-Message-Number: 24908
Date: Sat, 23 Oct 2004 11:41:45 -0700 (PDT)
From: Doug Skrecky <>
Subject: 157'th update on fly longevity experiments
This is the 157'th update of my fly longevity experiments. Average
temperature was 27.7 C during this run. Estimated maximal longevity using
the formula (363 - T*11.2) is 53 days.
Citric acid has become a standard additive since it was first proved
to increase survival. I had attributed this to a reduced bacterial load
in the acidified fly food. Since I began rotating my breeding bottles
more frequently, fly longevity has increased. Explicit retesting of
citric acid has now tended to question its utility. Here I retest citric
acid at various doses to settle this question conclusively. I also check
to see if adding a little extra water yields any benefit, since adding a
little extra water to breeding bottles increased their yield.
No consistent effects for extra water are noted in this run. However
the effect of increased citric acid has now been reversed! Recent
published research has found that exposure of young flies to low doses of
bacteria actually increased their subsequent survival. It is possible
that my flies now have a sufficiently low bacteria exposure, that the
addition of an acidifing agent to the food now has harmful effects.
Run #157 Percent Survival on Day
supplement 10 21 26 32 37 42 47 52
________________________________________
citric 1/8 tsp 100 68 56 52 28 4 0 -
"+1 tsp water 85 58 50 39 27 15 0 -
citric 1/4 tsp 100 47 32 26 16 0 - -
"+1 tsp water 100 47 37 26 21 5 0 -
citric 1/2 tsp 96 50 23 18 5 0 - -
"+1 tsp water 96 59 41 27 14 9 5 0
"+2 tsp water 94 61 39 17 6 0 - -
citric 1 tsp 94 22 22 22 6 0 - -
"+1 tsp water 95 37 32 5 0 - - -
"+2 tsp water 93 64 14 7 7 0 - -
citric 2 tsp 84 5 0 - - - - -
"+1 tsp water 100 36 5 0 - - - -
"+2 tsp water 90 21 5 0 - - - -
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